Guest post: On coral alarmism

This is a guest post by Geoff Price, who blogs at pressing wax and tweets as @geoffmprice. The post first appeared here and starts now.

Even pretty staggering changes in the natural world can struggle to compete for attention amid the cacophony of modern media and cage-fighting politics (which of course can concern many other topics relevant to human well-being, on top of a near-infinite capacity for distraction).

In our window of time here and on our watch, we’re observing the unfolding collapse of global coral reef cover – the largest living structures on the planet, relatively priceless in terms of human and economic value, and stunningly beautiful – due to human-induced stresses, now most prominently from human-caused global anthropogenic (greenhouse) warming of the oceans.

Some articles in major media break through, e.g. Global Warming’s Toll on Coral Reefs: As if They’re ‘Ravaged by War’, though the impact on public awareness and policy action remains low. The impact is global including the Great Barrier Reef (GBR), Japan, the South Pacific, Hawaii, the Florida keys, and Belize.

bleaching global 2016

Naturally thinking about such things is hard, and for many – unfortunately including currently in power political parties drafting environmental policy – this dramatic plight of corals is already enjoying far too much attention. They feel the problems are likely exaggerated or contrived to justify policy actions around reducing greenhouse gas pollution. “Coral alarmism”.

Mass Bleaching

Having a skeptical orientation, I’ve engaged with science-disputing claims online for years. I noticed some comments on a U.K. science-disputing web site along these lines – “RIP beautiful coral reefs. (sniff, sniff, *reaches for Kleenex*)” – and had a discussion with the locals, then decided to post and expand on the response here.

What’s happening? In a nutshell, the main cause of the observed escalation of mass bleaching and coral death is heat stress. When temperatures are elevated above previously normal seasonal peaks for extended periods of time, coral bleaches (expel symbiotic algae). If it stays bleached long enough, it can die from the coral equivalent of asphyxiation.

bleaching severity trend

The relationship with ocean temperature is fairly direct. Scientists now closely monitor temperature and bleaching risk (from Heron et al 2016):

Satellite monitoring of thermal stress on coral reefs has become an essential component of reef management practice around the world. A recent development by the U.S. National Oceanic and Atmospheric Administration’s Coral Reef Watch (NOAA CRW) program provides daily global monitoring at 5 km resolution—at or near the scale of most coral reefs… Analysis of coral community characteristics, historical temperature conditions and thermal stress revealed a strong influence of coral biodiversity in the patterns of observed bleaching. This resulted in a model based on thermal stress and generic richness that explained 97% of the variance in observed bleaching.

Since the core driving factor is water temperature, it’s pretty easy to see how the growing scale of bleaching is directly tied to global (ocean) warming. And in fact it’s pretty straightforward to show this statistically.

Mass… El Niño?

But facing human-driven problems on this scale is hard emotionally – what do you do if you don’t want this to be true?

Well we could look to blame big weather system events. And there is one in particular that attracts our attention right away – all tropical storms bow before El Niño.

Global El Niño (weather) conditions elevate surface ocean temperatures in a multi-month oscillating pattern (the “O” in ENSO). So blaming the bleaching on El Niño has been one of the more common (frequently absurd) contrarian responses, as in this case.

Our blogger, Jaime Jessop, opens by casually assuming that since mass bleaching was “first recorded during warmer than average El Niño conditions”, El Niño is the key. And a-ha – “there have only been three recorded ‘very strong’ or super El Niño events since 1950”, so how can we say if such bleaching is unusual or not? Of course there were strong El Nino events in 1957, 1966 and 1972 too, and by recent times mass bleaching recorded under quite mild El Niño conditions in 2002 and 2005, but it’s not really necessary to discuss in this detail.

A more significant problem with this theory is that the most recent mass bleaching on the GBR (spring of 2017 – 20% or more total mortality per GBRMPA) happened under ENSO Neutral conditions, rather than El Niño. So… whoops.

Jessop cites a Guardian article noting that mass bleaching is now happening independently of El Niño, and indulges in some misplaced indignation:

“Any time”? That would imply that mass coral bleaching is occurring randomly regardless of El Niño events. This is clearly double Dutch from the Guardian

It ain’t “double dutch”. El Niño events encourage more pooling of warm water on the surface, especially in some parts of the Pacific, which is why we tend to see new temperature peaks in such conditions. But it is simply elevated water temperature that is choking off coral.

The total oceans have warmed such that sustained regional high temperature conditions are more common even under ENSO Neutral (and La Nina) conditions. This is reasonably straightforward; disputing it would require competing physical explanations and supporting evidence.

The Science of Escalating Impact

Readers will be familiar with two CO2-related threats to coral – ocean warming (from the anthropogenic pollution of greenhouse gases in the atmosphere) as well as ocean acidification. The latter is a separate topic that impacts the productivity of calcium carbonate skeleton/reef construction (implicated in longer term reef gaps in earth’s past). The mass bleaching die-offs we’re seeing in the last few years are simply a direct result of the former – the increase in the water temperature in which coral are immersed.

Intuitively, many people feel it is unlikely for coral to be so heavily impacted by the mere 1°C (~2°F) increase in average temperature that has happened globally so far – partially because as land creatures we are biased to think in terms of air temperature where there is much less effect from small changes in temperature (air being less dense.)

A more useful mental experiment might be to imagine the impact of a sustained full 2°F increase in your body temperature, or of how much longer you could survive submerged in a hot tub at 105°F vs. 107°F.

To start, bleaching via thermal stress is lab reproducible and uncontroversial. If you’re curious, see Jones et al 1998, “Temperature-induced bleaching of corals begins with impairment of the CO2 fixation mechanism in zooxanthellae”.

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Timelapse of zooxanthellae explusion, coral bleaching

Reef experts have been warning about risks for some time, well before the major mortality events of 2016 and 2017. The topic is hardly new or contrived for political purposes. Reaser et al 2000, reviews some of the history of research attention in “Coral Bleaching and Global Climate Change: Scientific Findings and Policy Recommendations”:

Nearly 80 years ago, Alfred Mayer described coral bleaching as a natural event, when he observed small scale bleaching in overheated tide pools (Goreau & Hayes 1994). Because the events were rare, localized, and corals typically recovered, bleaching events caused little concern … in the early to mid 1980s, however, coral reefs around the world began to experience large scale bleaching (Goenaga & Canals 1990; Goreau 1990; Williams & Bunkley-Williams 1990; Glynn 1991; Hayes & Goreau 1991; Goreau 1992; Glynn 1996; Brown 1997) … Corals have died throughout entire reef systems following mass bleaching events … Recovery of coral reefs is dependent on numerous factors, including the local severity and duration of thermal stress … recovery to previous levels of coral cover … could take decades to possibly hundreds of years. Some corals have survived the mass extinctions brought on by natural climactic variabilities in the past (e.g. 75,000 years ago). Because of the rapid rate at which significant climactic changes could now proceed, however, the ability of most corals to acclimatize, migrate, or adapt is uncertain and unsubstantiated (see discussion by Hoegh-Guldberg 1999). … Hoegh-Guldberg (1999) examined four predictive climate-change models to project the increasing severity of mass coral bleaching events. All four models confirmed the same trends: the frequency of bleaching will rise rapidly… within 3-5 years most regions will experience mass bleaching annually.

The Global Coral Reef Monitoring Network, an international network of marine ecologists and organizations organized around practical efforts to monitor and conserve reefs, highlighted the growing threat from climate change in its summary report “Status of Coral Reefs of the World: 2008

current rates of climate change pose the greatest threat to the long-term sustainability of coral reefs and human coastal communities

Another example paper, Berkelmans et al 2004, described the growing scale of bleaching events on the Great Barrier Reef in 1998 and 2002 and noted the likelihood of future “large declines” under continued warming:

Since 1979, the number, scale, and intensity of reported coral bleaching events has grown dramatically and this trend has been linked to climate change… results suggest that coral reefs are profoundly sensitive to even modest increases in temperature and, in the absence of acclimatization/adaptation, are likely to suffer large declines under mid-range International Panel for Climate Change predictions by 2050

Researchers apply modeling to better estimate the extent of carnage under the most likely ocean warming trends. Frieler et al 2013 uses general circulation models to provide the alarming warning that “Limiting global warming to 2 °C is unlikely to save most coral reefs

We show that preserving >10% of coral reefs worldwide would require limiting warming to below 1.5 °C (atmosphere–ocean general circulation models (AOGCMs) range: 1.3–1.8 °C) relative to pre-industrial levels

And finally, the Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report summarized these projections starkly:

Coral reefs within CBS, SES, and STG are rapidly declining as a result of local stressors (i.e. coastal pollution, overexploitation) and climate change (high confidence). Elevated sea temperatures drive impacts such as mass coral bleaching and mortality (very high confidence), with an analysis of the Coupled Model Intercomparison Project Phase 5 (CMIP5) ensemble projecting the loss of coral reefs from most sites globally by 2050 under mid to high rates of ocean warming (very likely).

Hot Oceans

With a strong El Niño on top of global ocean warming, global temperatures reached new records around the world in 2016-2017. Those inclined to ignore or reject the warnings about coral met the most dramatic wake-up call yet – mass bleaching of nearly the entire 1,800 mile Great Barrier Reef, resulting in death of as much as half the coral.

Aerial and dive surveys across the reef documented the destruction, and the paper Hughes et al 2017 , “Global warming and recurrent mass bleaching of corals” – with contributions from numerous major reef monitoring agencies including GBRMPA, AIMS, ARC and the U.S.’s NOAA – described the observed heat-bleaching relationship in detail:

The distinctive geographic footprints of recurrent bleaching on the Great Barrier Reef in 1998, 2002 and 2016 were determined by the spatial pattern of sea temperatures in each year. Water quality and fishing pressure had minimal effect on the unprecedented bleaching in 2016, suggesting that local protection of reefs affords little or no resistance to extreme heat. Similarly, past exposure to bleaching in 1998 and 2002 did not lessen the severity of bleaching in 2016. Consequently, immediate global action to curb future warming is essential to secure a future for coral reefs.

The paper included this graphic which compares (a) severity of bleaching with (b) sustained sea temperature, highlighting the spatial alignment (see key below).

GBR bleaching and temp(a) measured by extensive aerial surveys with dive-based ground truth validation: dark green (60%). The number of reefs surveyed in each year was 638 (1998), 631 (2002), and 1,156 (2016)

(b) Spatial pattern of heat stress (DHWs or degree heating weeks; °C-weeks) during each mass-bleaching event. Dark blue indicates 0 DHW, and red is the maximum DHW for each year (7, 10 and 16, respectively). Orange and yellow indicate intermediate levels of heat exposure on a continuous scale.

Returning to discussion of our cultural backlash, evidence like this obviously makes it hard to ignore the relationship of coral impact to ocean warming. This can tempt contrarians to retreat back to more generic rejection of anthropogenic warming itself (of course, a longstanding cottage industry of its own.)

In our contrarian article, Jessop offers a closing swipe of this sort, pretty typical of the genre. We’re offered a frequently circulated ISCCP chart that is claimed to show that global warming is due to some hypothesized tropical decline in cloud cover (mysteriously, amid generally rising tropospheric humidity).

The owners of this ISCCP data set unsurprisingly insist their data set provides no evidence of any such thing, as noted on the web page where the data is accessed, but the chart is what is described as a “zombie claim” in the climate propaganda wars. One more correction will doubtless not deter further recirculation, but for the record there is Evan et al 2007, “Arguments against a physical long-term trend in global ISCCP cloud amounts”:

Here we show that trends observed in the ISCCP data are satellite viewing geometry artifacts and are not related to physical changes in the atmosphere.

Observations of increasing ocean heat continue to pretty exactly match mean predictions derived from mainstream understanding of earth’s energy budget and the continually-validated greenhouse effect. This is really the core test of AGW theory – it derives from the notion of conservation of energy, the balance between incoming (solar, “shortwave”) and outgoing (infrared or “longwave”) radiation mediated by the planet’s ability to store or release energy in/from the ocean.

For example this article from Lijing, Jiang and Abraham 2015, “Global Upper Ocean Heat Content Estimation: Recent Progress and the Remaining Challenges”, or this summary graphic from NASA’s climate director highlighting the close match between model simulations and ocean heat content estimates and measurements (the quality of measurements increasing after 2000 with the deployment of ARGO):

OHC models

The short summary is that the evidence for greenhouse-driven warming of the oceans is strong (and obviously goes far beyond the above). The evidence for heat-induced mass mortality of corals is also extremely strong – spatial patterns of sustained heat and bleaching severity line up quite exactly, with well-understood biological mechanisms. Jessop’s article (and hundreds of others like it) don’t offer anything to dispute either of these things.

But Coral Have Been Around a Long Time

The main remaining argument, frequently raised, is a history-based argument from incredulity, per Jessop’s pasted tweet: “Corals have been around for, like, 250 million years and survived several major global extinction events”. Maybe coral are just inherently resilient, have faced such threats many times before and will quickly adapt?

This for example is the argument championed by Australia’s resident contrarian scientist (and marine dredging expert) Peter Ridd, quickly rising in popularity on partisan media. “Mass bleaching events are … almost certainly completely natural,” says Ridd. “There is perhaps no ecosystem on Earth better able to cope with rising temperatures than the Great Barrier Reef.”

Looking at the record, paleoecological (fossil/proxy) studies on the Great Barrier Reef can find “remarkable long-term stability in coral community structure” but also evidence of past bleaching, if not as frequent or widespread.

Biologically there is plenty of uncertainty about the extent of different coral species’ ability to migrate, adapt and survive. Some species are more resilient than others (and are naturally the ones with a greater chance of survival.) But pace of change and degree of stress are always key in these questions, as highlighted in the paper Hoegh-Guldberg 2012, “The adaptation of coral reefs to climate change: Is the Red Queen being outpaced?”

Coral reefs have enormous value in terms of biodiversity and the ecosystem goods and services that they provide to hundreds of millions of people around the world. These important ecosystems are facing rapidly increasing pressure from climate change, particularly ocean warming and acidification. A centrally important question is whether reefbuilding corals and the ecosystems they build will be able to acclimate, adapt, or migrate in response to rapid anthropogenic climate change. This issue is explored in the context of the current environmental change, which is largely unprecedented in rate and scale and which are exceeding the capacity of coral reef ecosystems to maintain their contribution to human wellbeing through evolutionary and ecological processes. On the balance of evidence, the ‘Red Queen’ (an analogy previously used by evolutionary biologists) is clearly being ‘left in the dust’ with evolutionary processes that are largely unable to maintain the status quo of coral reef ecosystems under the current high rates of anthropogenic climate change.

A recent paper Bay et al 2017 looks at evolutionary adaptation relative to current warming trends and finds the hopeful note that “Genomic models predict successful coral adaptation if future ocean warming rates are reduced”. Of course, reduced warming rates are not what are expected in the wake of currently rising emission levels, so the paper concludes similar to Frieler above:

Under more severe scenarios, RCP6.0 and RCP8.5, adaptation was not rapid enough to prevent extinction.

As a result the reasons for alarm remain quite clear. Looking further back in geologic history you can find multiple reef gaps after extreme climate and extinction events, sometimes millions of years long (with ocean acidification particularly implicated in sustained reef gaps). The coral species of today are quite different from those that were around say 250 million years ago. In particular, they did not actually survive the Permian extinction at that time.

Appropriate historical comparisons with current rates of climate change are tricky to even find. Anthropogenic warming appears very abrupt in geologic terms. The current human-driven rate of carbon release looks about 10x as fast as the nearest comparison, ~66 million years ago at the Paleocene–Eocene Thermal Maximum (PETM). The extreme disruption at the PETM event was associated with numerous extinctions, and “coral reefs suffered heavily during this ‘mini-extinction’ and most disappeared“.

(Some additional, interesting historical perspective is offered in the book A Reef in Time, The Great Barrier Reef from Beginning to End, by J.E.N. Veron, former chief scientist at the Australian Institute of Marine Science.)

All things considered, remember we are directly observing mass coral death. If coral reefs have some superpower that prevents them from dying off under aggressively changing climate conditions, we haven’t seen it yet. The reef cover trend is sharply down over time (exacerbated by multiple stressors.)

The key point is that the economic and biodiversity value of reefs scales with cover, not survival. Meaning it is how much reef we have that matters in terms of benefit to the oceans and to us. Large loss of biodiversity is expected (already detectable in dependent fish species), but some species absolutely may find niches and hang on, migrating on currents to cooler locales for example. But it takes centuries or millennia to rebuild reefs that fuel ocean wildlife and food sources on the scale of our existing giant tropical reefs – time that passes very slowly on human calendars. And this hypothetical future rebuilding of reefs is dependent both on climate actually stabilizing (no sign of this in the coming century) and the ability of coral to productively rebuild calcium carbonate reefs, where they face the parallel growing threat of shifts in ocean chemistry (acidification).

There are always open questions – climate, biochemistry and biodiversity are all complex. But smug complacency, to be blunt, can only be described as shocking collective madness at this point. Coral death is directly observed, not theoretical. The impact and risk are stark.

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208 Responses to Guest post: On coral alarmism

  1. verytallguy says:

    I’d be interested in your view as to how well, or otherwise, WG2 does at representing current science on this. Any comment?

  2. Along the Pacific equator, coral proxy readings calibrate extremely well with the modern instrumental ENSO signal as per the local SST.

    When they extend the readings back several hundred years, they observe that it reverts to a stationary mean with all the variance attributed to ENSO variability. So, from what I have been able to infer, little AGW signal is observed in any of the coral proxy numbers. However the variance is not stationary

    Something may have changed around 1880, Krakatoa perhaps?

  3. Mike Risk says:

    The loss of the world’s reefs will indeed be sad. Contrary to nonsense about reefs being “resilient”, the fossil record shows they have died like flies-a total wipeout at the K-T Boundary, for example, from which recovery took millions of years.
    But let’s not blame global warming for this. The Caribbean lost over half its coral cover before 1980. Corals on the GBR stopped growing a decade ago. Florida went from 45% cover to 4% in a decade-and bleaching had nothing to do with it.
    The sad fact is that, by the time bleaching entered our vocabulary and consciousness, the world had already lost most of its reefs due to land-based stresses. Sure, global warming is set to kill them all, but in this case it will only be kicking over the edge of the extinction cliff the last sad remnants.

  4. Mike,
    It’s certainly my understanding that other human factors have also contributed to stressing coral reefs. I do think, however, that climate change is one of the biggest risks, partly because it’s essentially irreversible on human timescales.

  5. geoffmprice says:

    verytallguy, IPCC was one of the sources I reviewed for this article (including for key papers cited). I highlighted the key summary above and there are a lot of mentions throughout (Chapter 19. Emergent Risks and Key Vulnerabilities) and Chapter 30 Ocean (lead author Hoegh-Guldberg, one of the authors cited here). I tried to keep language here consistent. It’s not really a ton of depth/detail, but that’s pretty consistent. It would be interesting to hear opinions from different marine and coral experts.

  6. geoffmprice says:

    Paul, interesting, thanks for sharing. The recent Kamenos paper (linked above) found more mixed signs “There were no consistent annually resolved site-specific differences in reconstructed bleaching in response to large scale climatic patterns (ENSO, PDO, and SOI) between or within different locations on the GBR (Figure 1B, Table SM1) over 138–503 year long periods (depending on core length). Only 12 of 44 coral cores showed evidence of bleaching in synchrony with large scale climatic processes. Bleaching was synchronous with ENSO extremes in six corals (Snapper core 01A, Normanby 01B, Britomart 01B, Pandora 04A, Wheeler 01A, Stanley 01A), PDO extremes in six corals (Agincourt 01B, Britomart 01B, Pandora 04A, Lupton Island 01A, Lupton Island 01C, Abraham 01H) and SOI extremes in five corals (Findlers 01A, Pandora 04A, Magnetic Island 01D, Stanley 01A, Abraham 01H).”

    What paper/coral/proxy data are you referring to, and what meaning do you attribute to it?

  7. geoffmprice says:

    Mike, yes, papers like De’ath 2012 estimated losses starting from 1985 in GBR and they were extensive, heavily from coastal runoff. To Ken’s point, those problems at least had potential solutions and room for conservation and recovery, with reefs farther from developed coastlines more protected. And there were still thousands of miles of those and billions of coral.

    Certainly a brutal storm of multiple stressors, with this giant and relentless one piled on top ‘kicking them over the edge’ as you say.

  8. KiwiGriff. says:

    This topical piece came up in my news feed this morning .

    Suffering in the heat: the rise in marine heatwaves is harming ocean species
    March 5, 2019 6.02am AEDT
    Recent marine heatwaves have devastated crucial coastal habitats, including kelp forests, seagrass meadows and coral reefs. Dan Smale,
    https://theconversation.com/suffering-in-the-heat-the-rise-in-marine-heatwaves-is-harming-ocean-species-112839

    Based on the recently published letter .
    Marine heatwaves threaten global biodiversity and the provision of ecosystem services.
    Dan A. Smale Et,al
    Nature Climate Change
    Published: 04 March 2019
    Abstract.
    https://www.nature.com/articles/s41558-019-0412-1
    The global ocean has warmed substantially over the past century, with far-reaching implications for marine ecosystems1. Concurrent with long-term persistent warming, discrete periods of extreme regional ocean warming (marine heatwaves, MHWs) have increased in frequency2. Here we quantify trends and attributes of MHWs across all ocean basins and examine their biological impacts from species to ecosystems. Multiple regions in the Pacific, Atlantic and Indian Oceans are particularly vulnerable to MHW intensification, due to the co-existence of high levels of biodiversity, a prevalence of species found at their warm range edges or concurrent non-climatic human impacts. The physical attributes of prominent MHWs varied considerably, but all had deleterious impacts across a range of biological processes and taxa, including critical foundation species (corals, seagrasses and kelps). MHWs, which will probably intensify with anthropogenic climate change3, are rapidly emerging as forceful agents of disturbance with the capacity to restructure entire ecosystems and disrupt the provision of ecological goods and services in coming decades.

  9. Jaime Jessop says:

    I’ve left a comment on that Conversation article:

    “All evidence suggests that marine heatwaves are linked to human mediated climate change and will continue to intensify with ongoing global warming.”

    This would appear to imply that no evidence exists linking marine heatwaves to natural events (changes in weather patterns mediated via the NH and SH jet streams), in particular extreme El Nino events. The latter is obviously not the case by your own admission as you state that half of the marine heatwaves you studied are associated with El Nino events. Nevertheless, you stray into policy advocacy on ‘all the evidence’ by stating:

    “The impacts can only be minimised by combining rapid, meaningful reductions in greenhouse emissions with a more adaptable and pragmatic approach to the management of marine ecosystems.”

    It’s not a good look for a scientist to be advocating radical policy on GHG emissions reductions to prevent MHWs when their own research demonstrates that at least half (very possibly more) of the MHWs they studied are associated with naturally occurring weather events.

  10. Jaime,
    Our emission of CO2 into the atmosphere is warming the planet. Hence, the primary reason why we’re seeing more heatwaves, and more intense heatwaves, is because of human-mediated climate change. One can argue about terminology, or claim that we can’t completely rule out some alternative, but this it is almost certain that it is pre-dominantly our influence.

    It’s not a good look for a scientist to be advocating radical policy on GHG emissions reductions to prevent MHWs when their own research demonstrates that at least half (very possibly more) of the MHWs they studied are associated with naturally occurring weather events.

    The Conversation article is here and as you yourself highlighted, they explicitly say will continue to intensify with ongoing global warming. A key point is that this is mostly about trying to avoid more extreme scenarios in the future. It is now abundantly clear that minimising the future risks to marine ecosystems will require emitting less CO2 into the atmosphere than we otherwise could. I think it’s entirely reasonable for a scientists to say what you quoted because it is what the evidence is indeed indicating.

  11. chrishod says:

    Jaime Jessop talks past the point that bleaching now does not require the height of an el Nino as once it did. El Ninos are now hotter water events; ENSO neutral events are now hotter; even la Nina has hotter water. In that context talking about events as ‘associated with naturally occurring weather events’ is just hand-waving.

  12. Jaime Jessop says:

    Ken,

    “Our emission of CO2 into the atmosphere is warming the planet. Hence, the primary reason why we’re seeing more heatwaves, and more intense heatwaves, is because of human-mediated climate change.”

    That is merely a statement. For it to be considered as a fact, you need good evidence. I don’t see an abundance of that. The evidence for a projected future increasing trend in frequency and duration of MHWs is via GCMs, which do a very poor job of modeling natural oceanic variability, ENSO, PDO, AMO, regional differences in basin warming etc. So that statement must also be taken with a pinch of salt too.

    But anyway, thanks for removing my comment from moderation.

  13. Jaime Jessop says:

    “Jaime Jessop talks past the point that bleaching now does not require the height of an el Nino as once it did. El Ninos are now hotter water events; ENSO neutral events are now hotter; even la Nina has hotter water. In that context talking about events as ‘associated with naturally occurring weather events’ is just hand-waving.”

    Not at all chrishod. I presume your analysis relies upon one data point: that being the three year global bleaching event 2014-17, centred on the 2015/16 super El Nino, where mass bleaching took place technically during (very weak) La Nina and ENSO neutral conditions. It would be rather premature to assign this one particular event as evidence of a trend.

  14. izen says:

    @-JJ
    “The evidence for a projected future increasing trend in frequency and duration of MHWs is via GCMs, which do a very poor job of modelling natural oceanic variability”

    Natural ocean variability has little influence beyond determining when extreme warming events occur. The trend in increasing events is the result of the oceans acquiring more energy. No GCMs are required to observe that, the rise in sea level from thermal expansion is one obvious sign.

    And ‘natural oceanic variability’ has absolutely NO influence on ocean acidification from rising CO2. The other negative externality of our dependence on burning fossil carbon.

  15. Jaime,

    That is merely a statement. For it to be considered as a fact, you need good evidence. I don’t see an abundance of that. The evidence for a projected future increasing trend in frequency and duration of MHWs is via GCMs, which do a very poor job of modeling natural oceanic variability, ENSO, PDO, AMO, regional differences in basin warming etc. So that statement must also be taken with a pinch of salt too.

    The radiative impact of adding CO2 is very well understood. There is some uncertainty about feedbacks, but these almost certainly amplify CO2-driven warming. This has little to do with GCMs and is mostly a combination of some fairly basic physics and an understanding of past climate changes. It is pretty certain that the main reason we’re seeing, and will continue to see, an increase in the frequency and intensity of heatwaves is our emission of GHGs into the atmosphere.

  16. dhogaza says:

    Even if Jaime were correct in stating that “the evidence for a projected future increasing trend in frequency and duration of MHWs is via GCMs”, and nothing else, the situation regarding the modeling of the ocean systems isn’t as abysmally poor as hesuggests. The fact that ENSO events are emergent properties of CGCMs at all is something I find quite impressive and tells us they’re getting a lot right.

    Here’s a nice piece which focusing on the use of CGCMs for forecasting specific ENSO events. Like all efforts to model weather vs. climate the forecasting skill is limited, but I’d say that it’s good enough so that blowing off CGCMs with a hand wave like Jaime has done, and suggesting we ignore what they teach us about changes in ENSO and other events in the ocean as the planet warms, is unwarranted.

    Besides which, we then have physics 🙂

    https://www.climate.gov/news-features/blogs/enso/challenges-enso-today’s-climate-models

  17. Dave_Geologist says:

    For it to be considered as a fact, you need good evidence. I don’t see an abundance of that.

    There’s a reason for that Jaime. Six letters, starts with D, ends with l.

  18. JJ said:
    “which do a very poor job of modeling natural oceanic variability, ENSO, “

    The players most responsible for misdirected modeling of natural variability are the usual suspects of Tsonis, Curry, Webster, Salby, Lindzen. It’s a “good look” to take whatever these scientists say with a grain of salt.

    Look at the figure I posted for Christmas Island coral proxy/SST from Kim Cobb et al (who is Curry’s former GaTech colleague and now chief nemesis). Notice the coral bleaching event during the 1998 El Nino.

    BTW, Tsonis of the GWPF in particular has gone off the deep end with respect to ENSO modeling. At the recent AGU, he asserted that ENSO was now synched to solar spot variability (!)

  19. izen says:

    @-JJ
    “It would be rather premature to assign this one particular event as evidence of a trend.”

    But entirely reasonable to observe that it confirms that the correlation is between temperature and bleaching independent of the particular state of the ENSO quasi-cycle.

    The situation may not be entirely hopeless however. While much of the global coral reefs may be diminished by the warming in the pipeline, it is possible for coral to evolve and adapt to the higher temperatures. This has already happened locally where coral has evolved in a very warm water environment completely independent of the ENSO/global influences.

    https://phys.org/news/2017-06-red-sea-coral-reefs-climate.html
    “In the Red Sea, coral reefs can take the heat of climate change”

    The problem is that losing the present coral reefs is still bad even if they can be rebuilt/replaced by heat tolerant versions. It is rather like losing tropical forests, the biodiversity and productivity is lost unless and until an alternative replaces it.

    A stray thought, how much CO2 does coral sequester from the Carbon cycle, would the loss of this active participant and its local enhancement of biological productivity, have any impact on the amount of Carbon the oceans can absorb ?

  20. Coral bleaching is governed by many processes. Here’s a paper from last month indicating other, e.g. tidal forcing, factors have an influence
    “Physical mechanisms influencing localized patterns of temperature variability and coral bleaching within a system of reef atolls”

    “Here, we identify three mechanisms at Scott Reef that alleviated heat stress during the marine heatwave in 2016: (1) the cool wake of a tropical cyclone that induced temperature drops of 1.3 °C over a period of 8 days; (2) air–sea heat fluxes that interacted with the reef morphology during neap tides at one of the atolls to reduce water temperatures by up to 2.9 °C; (3) internal tidal processes that forced deeper and cooler water (up to 2.7 °C) into some sections of the shallow reefs. The latter two processes created localized areas of reduced temperatures that led to lower incidences of coral bleaching for parts of the reef. We predict these processes are likely to occur in other similar tide-dominated reef environments worldwide.”

  21. Jaime Jessop says:

    dhogaza says:

    “Here’s a nice piece which focusing on the use of CGCMs for forecasting specific ENSO events. Like all efforts to model weather vs. climate the forecasting skill is limited, but I’d say that it’s good enough so that blowing off CGCMs with a hand wave like Jaime has done, and suggesting we ignore what they teach us about changes in ENSO and other events in the ocean as the planet warms, is unwarranted.”

    The article he references says:

    “Until we understand more, we may have to come to terms that, for the foreseeable future, ENSO may not be reliably predicted more than a few months in advance. As for how ENSO and its impacts will change under climate change, more knowledge is expected in the next several years as we try to reduce model errors by better representing the many individual processes that preside over ENSO.”

    I think that rather blows off the argument that current GCMs are anywhere near good enough to model ENSO variability. Of course, if they were, they would need to explain this graph:

    If GHG global warming increases say, the intensity of El Nino events, why were there more powerful El Ninos at the end of the 19th century compared to a relative lull during the mid 20th century, followed by an increase in intensity of El Nino events in the late 20th/early 21st century?

  22. Chubbs says:

    Paul’s enso chart showing increased variability is consistent with expectations. AGW increases ocean stability and the impact of upwelling by warming surface waters.

  23. JCH says:

    ENSO did it. That is so freakin’ worthless.

  24. Chubbs says:

    Jaime is right no model is going to predict enso. The Pacific warm pool is strengthening and expanding. We will just have to sit back and see what happens.

  25. Jaime Jessop says:

    Paul, ENSO variability is, as far as I am aware, as poorly understood in terms of natural variability as it is poorly modeled by GHG driven GCMs. You rightly point out also that specific coral bleaching events have causes other than, or additional to, high water temperature.

  26. Jaime Jessop said:

    “Paul, ENSO variability is, as far as I am aware, as poorly understood in terms of natural variability as it is poorly modeled by GHG driven GCMs. “

    Try to keep up with the research literature and don’t read what Tsonis and others say about ENSO. It’s becoming increasingly clear that ENSO is modeled well by elementary tidal forcing solved via simplifications of Laplace’s Tidal Equations along the equator. No need for GCM’s for the time being, as simple topological equatorial models are working out quite well. Perhaps in the future as the tidal forcing factors are added to GCMs.

    “You rightly point out also that specific coral bleaching events have causes other than, or additional to, high water temperature.”

    Sorry, I really don’t think you have any clue as to what is happening. You’re just grasping at straws.

  27. Jaime,
    There is a vaste difference between not being able to model the timing of internally-driven processes and simulations not being able to model such processes.

  28. Exactly. There is a huge difference in our understanding of something so basic as AGW and something that is orders of magnitude more complicated due to the nonlinear math of fluid mechanics. Jaime is just pot-stirring.

  29. dhogaza says:

    Jaime,

    Yes, the piece I referenced says:

    “As for how ENSO and its impacts will change under climate change, more knowledge is expected”

    More knowledge doesn’t imply, as you suggest, that scientists don’t know squat about how ENSO will change as global warming progresses. By your reasoning, since there will always be more to learn, we’ll never know enough to say anything of value on the subject.

  30. Jaime Jessop says:

    Paul, obviously, I won’t bother to respond to any more of your comments, as you appear to grasp at the opportunity to try to point-score by going completely off topic.

    Ken,

    There is a vast[e] difference between not being able to model the timing of internally-driven processes and simulations not being able to model such processes.

    Both apply.

  31. Jaime,
    I don’t think the latter is quite as true as the former. All models are wrong, some are useful. We may not be able to model the ENSO variations perfectly, but the idea that we can’t model them at all is not true.

    This is all a bit moot, though. ENSO cycles are clearly internal cycles that really can’t play a role in long-term warming. The real reason for the increase in the frequency and intensity of heatwaves is our emissions of GHGs into the atmosphere, not internally-driven cycles.

  32. Jaime Jessop says:

    dhogaza,

    What scientists do know about how ENSO evolves as global warming proceeds is dwarfed by what they don’t know.

  33. Jaime,
    How can we possibly know how much we don’t know?

  34. Jeffh says:

    There is abundant evidence that extreme events linked with anthropogenic global warming are most certainly negatively affecting biodiversity in freshwater, marine and terrestrial ecosystems. Not only heatwaves, which have a human fingerprint all over them, but more intense cloudbursts and prolonged droughts. Coral reefs are simply used as proxies by climate change deniers who ignore a wealth of data in the empirical literature showing deleterious effects on biodiversity at all levels of organization in multiple biomes. The recent heatwaves that wiped out a significant number of white spectacled bats in Australia were exceptional but are fast becoming the norm. Insect declines are occurring across the biosphere, and there is little doubt that rapid warming is playing a role in lower latitudes. In tropical biomes, ectotherms are very often adapted to a much narrower range of abiotic conditions than species in temperate biomes, where seasons are much more pronounced. When temperature thresholds exceed critical levels or tipping points for extended times, as Lister and Garcia recently showed in their Puerto Rico insect study (PNAS, 2018), then the result can be catastrophic and can work their way up the food chain. Research by one of my own PhD students as well as colleagues elsewhere is finding that prolonged heatwaves and sharp, intense rain events affect insect behavior and physiology, such as reproduction, phenology and survival, often in highly non-linear ways. The prolonged heat and drought across much of Europe last year was 30 times more likely to have occurred because of AGW according to the UK Met Office.

    Coral bleaching is clearly connected with AGW, even if it other anthropogenic factors are involved. Teasing apart these factors is not necessarily easy, but in no way does this negate the harmful effects of extreme climate-change related processes on biodiversity. More and more attention is being paid to extreme climate change-related events and the prognosis is not good.

  35. Jaime said:

    “Paul, obviously, I won’t bother to respond to any more of your comments, as you appear to grasp at the opportunity to try to point-score by going completely off topic.”

    The topic is the high sensitivity of coral to environmental factors. The lesson to you is not to chime in on a topic you know little about.

    The psychological projection on your part is to point-score by focusing on physics that is bleeding edge and trying to make that into a failure of consensus. Recall that Navier-Stokes is a Millenium Challenge problem … therefore technology fail 🙂

  36. Jaime Jessop says:

    Ken, simple. It is a measure of that which we cannot explain compared to that which we can explain. 🙂

  37. Jeffh says:

    Jaime, we understand more than enough. You are simply exaggerating the uncertainties. Oreskes and Conway explain why this is done in ‘Merchants of Doubt’. Instead of doing their own research, most climate change deniers simply sit on the sidelines sniping away at the empirical research that they don’t like. Once again, the aim is to maunfacture and exaggerate doubt. This is enough to inhibit or prevent anything being done. Science isn’t on your side and you know it, but as long as you can inflate the uncertainties then you don’t need to prevail with science.

  38. dhogaza says:

    Jaime,

    ” Ken, simple. It is a measure of that which we cannot explain compared to that which we can explain.”

    Thank you. Since it is simple, surely you can quantify it for us. Quickly. Easily. No handwaving.

  39. dhogaza says:

    Jaime,

    “What scientists do know about how ENSO evolves as global warming proceeds is dwarfed by what they don’t know.”

    Yet we know enough that CGCMs, built from first principles, i.e. physics, when run generate ENSO patterns as an emergent property. That shows that our in-depth understanding of the physics is sound. The physics explains in good detail what you claim we cannot explain.

    Again, though, since you claim that measuring that which we cannot explain compared to that which we can explain is simple, please do so. Please prove to us that the set of unknown and known unknowns has more members than the set of known explanations regarding how ENSO will evolve as global warming proceeds.

    No handwaving. You’ve made a claim, back it up. Empirically.

  40. dhogaza says:

    Jaime,

    “If GHG global warming increases say, the intensity of El Nino events, why were there more powerful El Ninos at the end of the 19th century compared to a relative lull during the mid 20th century, followed by an increase in intensity of El Nino events in the late 20th/early 21st century?”

    It appears that you don’t realize that the ENS ONI graph you reference is plotting anomalies, not temperature. Assuming that by “intensity” you mean the amount of energy sloshed to the eastern Pacific during an ENSO event, this anomaly graph doesn’t provide any information in that regard.

    As far as this comment by you goes:

    “I think that rather blows off the argument that current GCMs are anywhere near good enough to model ENSO variability. Of course, if they were, they would need to explain this graph”

    Once again, you’re conflating the ability to model variability with the ability to model a series of specific events. CGCMs do model ENSO variability quite well, again, as an emergent property resulting from the basic physics that the model is built on. Models will never model specific events precisely far in the future, i.e. weather vs. climate, but this isn’t necessary, and I suspect you know this despite your posturing.

  41. dhogaza says:

    Dave_Geologist,

    “There’s a reason for that Jaime. Six letters, starts with D, ends with l.”

    Oh, my, Jaime has his own blog. Skimming it for a bit, I’m afraid your assessment might be right.

  42. Jaime Jessop says:

    Dhogaza,

    AOGCMs, using parametrizations for a number of the physical processes involved, produce, perhaps not that surprisingly, a quasi-periodic oscillation which resembles El Nino in the real world. You are claiming this as some sort of modelling success which you further claim I am conflating with the ability of models to predict the timing and characterisation of specific events. You are wrong. I claimed that the models simulate ENSO variability very poorly. They do. They almost completely fail to characterise past modes of ENSO variability and the spread of projections of future ENSO variability, though it has narrowed somewhat in recent years, is still very wide. It is not just a failure to predict specific events; it is a comprehensive failure to capture the modes of internal variability of ENSO under external forcing (GHGs, volcanic forcing, solar forcing). This is perhaps unsurprising as the modes of variability of ENSO seem more closely related to multidecadal modes of variability, which models also fail to adequately simulate.

  43. Jaime Jessop says:

    “Oh, my, Jaime has his own blog. Skimming it for a bit, I’m afraid your assessment might be right.”

    Oh my, this thread is evolving almost exactly as I predicted it would when I commented. This means that my model for predicting interactions on ATTP’s blog is way better than the CMPI5 ensemble’s simulation of ENSO, but perhaps this is unsurprising, given that the processes I am modeling are an awful lot simpler!

  44. Mitch says:

    I get tired of reading comments from people like Jaime that argue that the inability to precisely predict when ENSO will occur is an argument that we know nothing. He is apparently unaware about the issues to predict a chaotic system. For ENSO it typically takes longer than a year to build up the Western Pacific warm pool, and to get an ENSO there is a need for the atmosphere to reinforce the annual cycle of warm flow back across the Pacific.

    However, it brings in the comments…

  45. Jaime Jessop says:

    Mitch, I get tired of people who misinterpret or don’t read my comments. See 4.18pm. Also, I get tired of people who assume that Jaime is a male name. It isn’t, in my case.

    As this thread has descended, entirely predictably, into insults, I shall leave it here.

  46. Let’s not let this comment thread degenerate into a slanging match. I will also point out that Jaime has her own blog.

    Jaime,
    I’m not quite sure what you’re really expecting. You’re making all sorts of claims without providing any evidence and without really providing any indication that you actually really know what you’re talking about, or why it’s even all that relevant. The increase in the intensity and frequency of heatwaves really has nothing to do with internally-driven cycles.

  47. verytallguy says:

    1. Jaime is putting forward a red herring. Prediction of the overall behaviour of a chaotic system such as ENSO does not mean individual ENSO events can be predicted. See also weather vs climate.

    2. Please can we get back to the point, which is the impact of ever rising temperatures on coral reefs. Changes in ENSO driven by these changes in temperature are an interesting but second order effect.

  48. JCH says:

    For what it is worth, Professor Curry makes ENSO prediction because she thinks ENSO is predictable. So her last years prediction appears to have been pretty accurate.

  49. dhogaza says:

    Jaime,

    I note that you’re not making any effort to back up your unsubstantiated claim that what we don’t know about ENSO dwarfs what we do know. If you believe that to be true, surely you can quantify how much we do know vs. how much we don’t know. Because if you can’t, how do you know one value “dwarfs” the other?

    Meanwhile, you’ve moved on to another unsubstantiated claim:

    “AOGCMs, using parametrizations for a number of the physical processes involved, produce, perhaps not that surprisingly, a quasi-periodic oscillation which resembles El Nino in the real world”

    This appears to be a tuning-through-parameterization argument, though you’re not clear. I also note that you’re not specific as to which parameterizations are responsible for giving rise to ENSO events as an emergent property. If you don’t know which are, then you don’t know that it is the parameterization of certain physical phenomena that’s responsible for this. And, of course, you’re assuming without presenting evidence that parameterization of phenomena that can’t be modeled on the grid scale the CGCMs operate on causes serious errors in model results.

    TL;DR more handwaving, unsubstantiated claims.

    No more from me, you’re a waste of time.

  50. Jaime Jessop says:

    The point, VTG, is that the ‘impact of ever rising temperatures’ – by which I take it you mean the secular trend in global mean SST, which disguises large ocean basin variability poorly modeled by GCMs – on coral reef mortality is far from demonstrated. The point is that ENSO-driven changes in mean global and regional SSTs are implicated far more directly in coral reef bleaching than the secular trend. That is why we are talking about ENSO and its role in marine heatwaves.

  51. Jaime Jessop says:

    Dhogagza. Last sentence. Ditto. Bye.

  52. The point is that ENSO-driven changes in mean global and regional SSTs are implicated far more directly in coral reef bleaching than the secular trend.

    Just for the benefit of lurkers, this is not what those who work on coral bleaching have concluded. There are a number of factors that can influence corals, but the underlying warming trend is regarded as a key reason why we have seen so much recent coral bleaching.

  53. Jaime Jessop says:

    “The point is that ENSO-driven changes in mean global and regional SSTs are implicated far more directly in coral reef bleaching than the secular trend.”

    Just for the benefit of both lurkers and non-lurkers, this is what the evidence firmly points to.

  54. Jaime,
    You can’t just keep claiming things. If you have some convincing evidence to back this up, then please show it. Ideally, something more than your own interpretation. Let’s not do science on blogs. Or, if you do want to do blog science, maybe you could make this clear (i.e., at least acknowledge what the scientific literature says, even if you disagree with it).

  55. Jaime Jessop says:

    “Jaime,
    You can’t just keep claiming things. If you have some convincing evidence to back this up, then please show it. Ideally, something more than your own interpretation. Let’s not do science on blogs. Or, if you do want to do blog science, maybe you could make this clear (i.e., at least acknowledge what the scientific literature says, even if you disagree with it).”

    Ken, if you bothered to read the blog post and the numerous comments from Geoff, myself and others at the blog post written by me which Geoff links to in this guest article, you will find there the precise arguments and evidence in support of my ‘claim’ that ENSO is implicated far more directly in mass coral bleaching events than the global warming secular trend. There is no point in me going through it all again here.

  56. Jaime,
    I would argue that it’s your job to provide the evidence. Plus, it wasn’t just for my benefit. Others will read your comments on this blog and wonder how you drew such strong conclusions. Can we clarify something though. It is your claim that ENSO is implicated more directly in coral bleaching than the global warming secular trend. This is not a claim that one would typically find in the scientific literature. Is that right?

  57. Marco says:

    “Just for the benefit of both lurkers and non-lurkers, this is what the evidence firmly points to.”

    Jaime Jessop seems to not realize that a positive deviation tends to go higher when it is superimposed on a secular upward trend…

  58. geoffmprice says:

    Thanks for stopping by Jaime.

    All of this is somewhat beaten to death in the article, but to try to pin down your claims (obviously a difficult point here per exchange so far):

    It sounds like you still fundamentally dispute observations of increasing heat wave events, i.e. rising frequency and severity of events where temps are elevated above expected summertime maximum, and/or you reject how this rise is naturally related to rising ocean temperatures as a whole.

    Models confirm the common sense result (I assume this is the Conversation article you mean, https://theconversation.com/great-barrier-reef-bleaching-would-be-almost-impossible-without-climate-change-58408), so you turn to dispute model skill.

    But your alternate theory – “that ENSO-driven changes in mean global and regional SSTs [independent of overall warming] are implicated far more directly” lacks any sort of modeling support whatsoever, even conceptually, does it not? Contrarians often critique GCMs for the fact that there are many different ones that handle different factors in different ways – do you think *any* model anywhere would lend some support to your theory? If not, why not?

    Since this is “And Then There’s Physics”, would you be willing to challenge yourself to frame your theory with a more physical and testable description? Even if just to speculate on mechanisms. Are you arguing greenhouse-warmed water is segregated in some way? I think people assume you are not, but it is hard to see exactly how you are mentally modeling your alternative theory.

    Saying warm periods are often “associated with” El Nino is a truism, so we can’t simply look for such “association” to test your theory in the way you imply, that’s circular. How is your model imagining the general warming is not affecting the local warming? Or what specifically is incorrect about the real-world observations, if anything, which marine scientists are reasoning from?

    Great if you could acknowledge, or explicitly dispute, dhogaza’s point that the ONI graph plots anomalies, not temperature. Do you think it is wrong to attribute the higher SST peak in the 2016 El Nino vs. the similarly-sized 1998 El Nino event, to the general warming of the ocean between those times, which is of a similar scale? Do you think the “local basins” of interest do not meaningfully contribute to that global SST peak in 2016? All this is essentially the same question. As Ken says, the only thing clearly coming across is that you notice that ENSO is involved in temperature and have fixated on this, per the original article here.

    Jaime [RE: La Nina] “It would be rather premature to assign this one particular event as evidence of a trend”

    There have been many bleaching events during La Nina, for varying reasons including generally rising temp.

    “average tropical sea surface temperatures are warmer today under La Niña conditions than they were during El Niño events only three decades ago… the link between El Niño as the predominant trigger of mass bleaching (3–5) is diminishing as global warming continues (Fig. 1) and as summer temperature thresholds for bleaching are increasingly exceeded throughout all ENSO phases.”
    http://science.sciencemag.org/content/359/6371/80

    Models of coral bleaching based on *temperature* predict this (and are therefore confirmed) pretty directly.

    Jaime “That is why we are talking about ENSO and its role in marine heatwaves”

    Well it is natural to talk about ENSO in the context of ocean temperatures, and of course researchers do so, but specifically here we are talking about ENSO because it has been the continuing, widespread, hand-waving contrarian talking point (in various forms, including WUWT/Steele’s infamous version) that has been broadcast on political media to reject the observations of escalating mass coral mortality. So citing the “fact that we are talking about ENSO” as evidence that its role is in fact central and causative is rather noticeable circularity, here.

    I know you have expressed a lot of passion for animals and wildlife and therefore die-off of billions of (sometimes hundreds of years old) coral in events like this is a pretty heavy topic to discuss. I think folks appreciate you engaging thoughtfully anyway.

  59. verytallguy says:

    Jaime,

    ENSO events cause high temperature spikes.

    ENSO events are superimposed on a warning overall trend.

    High temperatures cause coral reef stress and bleaching.

    To claim, as you seem to, that because bleaching events are correlated to ENSO events shows that ENSO events are more important in the long term than the overall warming trend does not logically follow.

    It’s not hard: ENSO causes short term warming. AGW causes more significant long term warming. Warming damages coral reefs.

  60. izen says:

    @-JJ
    “The point is that ENSO-driven changes in mean global and regional SSTs are implicated far more directly in coral reef bleaching than the secular trend.”

    Bleaching events right up to the point of virtual extinction of major coral reefs, will inevitably be the result of ENSO-driven changes in global and local SSTs.
    It is the balance of death to regeneration that is shifted by the secular trend. As bleaching events become more common, longer, and widespread with a rising secular trend they will exceed the ability of reefs to regenerate.
    Although the direct damage will always be attributable to a specific ENSO-driven variation, the already observed trend of shrinkage of reefs will be a result of the secular trend.
    (At least thats my take from the mainstream literature, any corrections welcome.)

  61. Windchaser says:

    It is your claim that ENSO is implicated more directly in coral bleaching than the global warming secular trend. This is not a claim that one would typically find in the scientific literature. Is that right?

    I don’t quite understand the argument about ENSO, either.

    If bleaching occurs primarily during El Nino events, during which the waters corals inhabit are warmer than normal, how does this imply that global warming is not a problem for corals? That seems backwards.

    I read Jessop’s blog post, as she recommended, but I don’t see anything that negates this point. Her argument seems to be “we don’t have enough data points to tell”. And maybe that’s true about extreme ENSO events, but it’s false with regard to global warming and coral bleaching.

    You can ignore ENSO events except as variability on a trend. The science shows (a) corals die off under warmer conditions, and (b) the oceans have indeed been warming. That’s the big picture.

  62. JCH says:

    “For what it is worth, Professor Curry makes ENSO prediction because she thinks ENSO is predictable. So her last years prediction appears to have been pretty accurate.”

    That would likely be a Curry & Webster prediction, most likely proprietary and thus worthless from an open research perspective.

    For those interested in signal processing, here is a preliminary post that demonstrates how crucial a perfectly periodic annual pulse is to driving the non-chaotic yet erratic ENSO behavior. IOW, it’s a significant clue to explaining what the underlying mechanism is.

  63. verytallguy says:

    Jaime’s argument could be applied to Arctic sea ice:

    Ice minimum is in the summer. It’s perfectly correlated every year. Therefore summer causes ice loss, not global warming.

  64. geoffmprice says:

    Well you have to say it better than *that*, tallguy

    “Seasonal changes in mean regional temperature continue to be strongly implicated in patterns of sea ice loss which are also related to multidecadal modes of variability, which models fail to adequately simulate. That’s the elephant in the room.”

  65. JCH says:

    Paul – I have no idea, but I believe she attributing the improvement in ENSO prediction to the European group.

  66. verytallguy says

    ” Prediction of the overall behaviour of a chaotic system such as ENSO does not mean individual ENSO events can be predicted. “

    Such a defeatist attitude 😦 There’s a lot left to learn before we have to resort to the “it’s chaos” dead-end.

  67. dhogaza says:

    Geoffmprice:

    “Seasonal changes in mean regional temperature continue to be strongly implicated in patterns of sea ice loss which are also related to multidecadal modes of variability, which models fail to adequately simulate. That’s the elephant in the room.”

    Brilliant.

  68. David B. Benson says:

    The only mystery here is the 4 letters between the D and the I. Beyond me but I know of a good ARMA model for ENSO; see Tamino’s Open Mind blog.

  69. Jaime Jessop says:

    Geoff,

    The graph I provided of ENS ONI (Ensemble Oceanic Nino Index) does not “plot anomalies” as claimed by dhogaza, who also wrongly claimed I was mistaken in thinking it was temperature. I suggest you read up a bit on how the ENS ONI was created using sea surface temperature datasets and sea level pressure data going back to 1870. The y-axis is not a temperature anomaly, it is an ENSO index, which reliably allows a direct comparison between the intensity of El Nino events over the entire period. But just for completeness, here is a graph of Nino3.4 actual SSTs from 1870 to 2010. You can see the mid 20th century lull in activity quite clearly, flanked by generally warmer SST Nino3.4 either side. Black is the actual SST3.4, red is the filtered data and the black dotted line is the trend.

  70. Jaime Jessop says:

    Top graph. Bottom graph IS temp anomalies.

  71. geoffmprice says:

    I wasn’t referring to this chart, but great that you sort of tacitly acknowledge you’re aware why similarly ‘measured’ El Nino in 2016 means higher temps than similar El Nino in 1998.

    Yes, I’ve looked into how ONI type metrics are calculated, “The ENS ONI closely follows the methodology of the Climate Prediction Center (CPC), and is computed by using seasonally averaged sea surface temperature (SST) anomalies in the NINO 3.4 region (5S-5N, 120-170W)” 🙄

    Can’t say I’ve really followed what tea leaf reading you are attempting here, speculating that El Nino is getting more severe? Also if you squint at pressure and a few other parameters on other planets you can debunk the existence of the greenhouse effect.

    And then there’s also physics and physiology, which say it is elevated temperature driving increasing mass mortality. You’ve declined to dispute this with anything discernible.

    Let’s let it go.

  72. Jaime Jessop says:

    Correction: it is the extended multivariate ENSO index which uses SLP data. No matter. Whether looking at actual Nino3.4 data, ENS ONI or ENS MEI, ENSO activity was high in the 1880s, declined mid 20th century and reached another maximum from the early 80s through to 2015/16. Tropical sea surface temperatures peak during powerful El Ninos. Most of the world’s corals inhabit tropical waters. The Global Coral Reef Monitoring Network was only set up in 1995. Observations were sparse before the early 80s. Global scale bleaching has been recorded during 1998 and 2014-17, mass bleaching occurred during 1982/83. All associated with powerful El Ninos. But the overriding influence on coral mortality is the secular warming of the tropical oceans due to GHGs; warming, I might add, which has been modest, rather less than the global average in the majority of tropical waters. Yes, let’s let it go.

  73. Willard says:

    > [T]he overriding influence on coral mortality is the secular warming of the tropical oceans due to GHGs; warming, I might add, which has been modest, rather less than the global average in the majority of tropical waters.

    Not sure I understand that sentence.

    ***

    > Ice minimum is in the summer. It’s perfectly correlated every year. Therefore summer causes ice loss, not global warming.

    Quite sure I understand that argument.

  74. Everett F Sargent says:

    The NOAA ONI is adjusted using 30-year means updated every five years …

    https://origin.cpc.ncep.noaa.gov/products/analysis_monitoring/ensostuff/ONI_v5.php

    I thought everyone already knew that?

    It is also general practice to show error bars for any time series. I’m quite sure data from 1865 are nowhere near as accurate as say post 1950’s as shown here …
    https://origin.cpc.ncep.noaa.gov/products/analysis_monitoring/ensostuff/detrend.nino34.ascii.txt

    It is rather cute to call old data accurate if it fits one’s POV, as JJ does here.

    Also, this is commonly known as blog science ,,,

    https://www.webberweather.com/ensemble-oceanic-nino-index.html

  75. Steven Mosher says:

    “It’s not a good look for a scientist to be advocating radical policy on GHG emissions reductions to prevent MHWs when their own research demonstrates that at least half (very possibly more) of the MHWs they studied are associated with naturally occurring weather events.”

    Its a worse look for a hack to suggest there is no risk

  76. Thanks Everett, good to remember that.

    “Due to a significant warming trend in the Niño-3.4 region since 1950, El Niño and La Niña episodes that are defined by a single fixed 30-year base period (e.g. 1971-2000) are increasingly incorporating longer-term trends that do not reflect interannual ENSO variability. In order to remove this warming trend, CPC is adopting a new strategy to update the base period.”

    Much of the time I use the SOI as an index for ENSO. This doesn’t require re-baselining as it is essentially a differential signal of the ENSO dipole. IOW, any drift cancels out.

  77. Everett F Sargent says:

    Hmm, interesting …
    https://journals.ametsoc.org/doi/suppl/10.1175/JCLI-D-18-0159.1/suppl_file/10.1175_JCLI-D-18-0159.s1.pdf
    “Figure S2. SST Uncertainty: Comparison of (a) the timeseries of detrended, area-average SST anomalies over the Nino 3.4 region and (b-d) average global SST anomalies during late-1877 (July-December) from the three datasets that have data extending back to the 1870’s – HadISST, ERSST and Kaplan SST. Anomalies are calculated relative to the 1901-1950 climatology.”

    These three datasets (HadISST, ERSST and Kaplan SST) have been detrended, BUT it is extremely self evident that these three reconstructions show much more uncertainty prior to 1950 than after 1950.

    The time series are only resolved at the annual level in Figure S2.

    Here is a different ONI graph (than the one JJ supplied) …

    https://climatedataguide.ucar.edu/climate-data/nino-sst-indices-nino-12-3-34-4-oni-and-tni

  78. Jaime Jessop says:

    Mosher,

    “It’s a worse look for a hack to suggest there is no risk”.

    It’s even worse for another hack to willfully misinterpret the argument of another hack by introducing the nebulous and somewhat contentious concept of ‘risk’.

  79. Jaime,
    Huh? The point is that under your scenario there is little risk to coral reefs, while virtually everyone who studies them thinks there is a great risk (essentially most people think that we will not be able to keep warming below 2C and expect this level of warming to do a huge amount of damage to coral reefs).

  80. Jaime Jessop says:

    Just what is your point Everett? ONI, ENS ONI, ENS MEI – they all differ slightly in their methodologies but all illustrate the point I was trying to make, namely, that ENSO activity was high during the late 19th century, declined mid 20th century, then increased once again late 20th/early 21st century. I provided a graph of actual Nino3.4 SSTs which also illustrated this point. I do recognise that SST data was very much more sparse and subject to greater uncertainty before 1950. I trust that those claiming the secular trend in ocean warming has caused coral reef die-offs also appreciate that. My point was that any climate model purporting to project the impact of increasing GHG forcing upon ENSO activity would need to explain the pattern of ENSO variability evident from the data and reconstructions. End of..

  81. Jaime Jessop says:

    Ken,

    Huh? Never once did I claim that corals were not ‘at risk’. My argument was the assessment of the nature of that risk. Geoff thinks that the risk is generated overwhelming via the secular increase in mean global ocean temperatures, which he attributes almost entirely to GHGs it would seem. I dispute that simplistic analysis. Coral die-off is a complex business and many factors, both natural and anthropogenic (in addition to global warming), contribute to the risk that the die-off will exceed the capacity of coral reefs to regenerate naturally, resulting in their decline and possibly even extinction.

  82. verytallguy says:

    Jaime’s point appears to be that temperature trends are not significant at tropical latitudes, or at least that they are insignificant compared to ENSO.

    That’s not true. Over climate relevant time periods the trend is clear and dominates over short term fluctuations (which includes ENSO)

    Tropical temperatures:

    And a nice animation:

  83. Jaime Jessop says:

    VTG,

    My point was that, in general, the tropical oceans have warmed less than the global average. You illustrate that point very nicely thanks.

  84. Jaime,
    My apologies for suggesting that you think there is no risk. You are right that there are many factors. However, a key factor is the long-term, anthropogenically-driven secular trend and there is a general acceptance that if the underlying warming exceeds about 2C globally that there will be extensive damage to coral reefs. This underlying warming is also essentially irreversible on human timescales. In other words, even though there are many factors, there is really only one over which we have some control but that we can only halt, rather than reverse.

  85. Jaime Jessop says:

    Noting that your graphs are for land and ocean surface temperature. Noting that the land has warmed faster than the oceans.

  86. Jaime,
    I’m not sure your claim is true, or – if it is – only just. The Arctic has warmed a lot more than the global average, and land warms more than the sea surface. But, I think tropical warming is – I think – actually quite similar to the global average.

  87. Jaime Jessop says:

    Ken, I voice no opinion on how the risk to coral reefs will evolve if global warming accelerates to 2C. My argument centers on whether or not the current modest increase in ocean surface temperatures has contributed very significantly to recent coral reef mass bleaching events.

  88. Jaime,
    Let’s quote from an actual expert. For example:

    Mass coral reef bleaching events have become five times more common worldwide over the past 40 years, new research finds, with climate change playing a significant role in the rise.

  89. Joshua says:

    Jamie –

    My argument centers on whether or not the current modest increase in ocean surface temperatures has contributed very significantly to recent coral reef mass bleaching events.

    Just to pin your opinions down a bit….

    Can you describe how you would quantify “very” significantly” and then quantify how much you think warmer surface temps have contributed to recent mass bleaching events?

    Also, is it only surface temps that most affects bleaching? If not, then could you quantify how much deeper water warming has contributed to mass bleaching? In other words, how informative are trends of surface temps for measuring impact on bleaching? Can we assume that changes in subsurface water temps track in step with surface temps?

  90. Jaime Jessop says:

    Er, yes, that paper was the subject of my blog post which Geoff referred to. The authors claim – without much evidence – that the long term secular trend in ocean warming is making corals more vulnerable to bleaching during El Ninos because the AGW ‘little bit on top’ of the much larger and far more rapid increase in temperature due to natural warming is somehow critical. They also argue – without much evidence – that global warming has somehow affected the frequency of mass bleaching events by affecting the frequency of powerful El Ninos. This is their ‘expert’ opinion. I am quite at liberty to dispute it by reference to contrary evidence, which you will find in that blog post.

  91. Jeffh says:

    Jaime writes, “My argument centers on whether or not the current modest increase in ocean surface temperatures has contributed very significantly to recent coral reef mass bleaching events”.

    This comment absolutely reeks of anthropocentricism. People are in no position to attribute the word ‘modest’ to describe the effects of human-mediated changes in abiotic conditions on biodiversity and complex adaptive systems. How on Earth do we know what is ‘modest’ when it comes to global change and how this is perceived by organisms in nature? Does a coral reef know what ‘modest’ means? Do white-spectacled bats? Harpy eagles? Did passenger pigeons? A change that seems ‘modest’ to us in terms of temperature or a change of some other environmental parameter may well be hugely significant for certain species or populations of species in nature. I might as well say that ‘modest changes’ in land use through intensive agriculture in Europe cannot be used to explain plummeting insect and songbird populations that are being documented. But of course they can. Apparently ‘modest’ changes in temperatures in tropical rainforests are having hugely harmful consequences on insects and food webs.

    Moreover, and most importantly, it isn’t mean changes that we necessarily need to be most concerned about, but the increase in the incidence of extreme events (e.g. heatwaves) that exceed critical tipping points which are of greatest concern. Longer term changes in temperatures often mask these extreme events that occur in the short-term. There is abundant evidence that the extent and magnitude of these extreme events is increasing because of climate change. A large and growing body of empirical literature is demostrating the harmful, and often lethal, effects of heatwaves, for example, on the biology and ecology of plants and animals. One of my colleagues is doing a meta-analysis on this right now.

    Jaime is most certainly not an ecologist, and she is in no position whatsoever to be able to attribute terms like ‘modest’ to increasing temperatures in relation to biotic responses.

  92. Jaime Jessop says:

    Joshua, corals inhabit near surface waters. The trend in surface temperature is therefore probably most relevant when examining the impact of higher water temperatures.

    Re. ‘significant’ – by which I mean deemed to be significant enough for scientists to declare that global warming is killing off corals. I think you’d have to get them to define exactly what they mean by significant.

  93. Jaime,
    They’ve been pretty clear. As this figure illustrates, if we warm by 2C, or more, there’s a very high chance of serious damage to coral reefs.

  94. Jaime Jessop says:

    ‘Modest’ in relation to past documented changes in ocean temperature, particularly throughout the ‘stable’ Holocene. For this I am accused of being a rabid anthropocentrist and “certainly not an ecologist”. Jeffh is probably not a paleoclimatologist.

  95. Jaime,
    Unless, I’m mistaken, Jeffh actually researches the impact of climate change on ecological systems. May be worth giving his comments a bit more credence than you seem to be doing. Just a thought, mind you.

  96. verytallguy says:

    My point was that, in general, the tropical oceans have warmed less than the global average. You illustrate that point very nicely thanks.

    In that case your “point” is entirely irrelevant, and your references to ENSO are also irrelevant.

    It matters not that tropical warming is less than global average, it matters that it is more than necessary to damage corals.

  97. Jaime Jessop says:

    Ken,

    I judge a comment by its content, not by the professional accreditation of the commenter. Best to keep things simple I find.

  98. Jaime Jessop says:

    VTG,

    “It matters not that tropical warming is less than global average, it matters that it is more than necessary to damage corals.”

    Please provide some evidence of that claim, more than the professional opinion of experts.

  99. verytallguy says:

    Jaime,

    I have no idea what you want evidence for. I am merely pointing out that the temperature that matters is the temperature where the corals are.

    *You* are proposing that it is in some way significant how this changes relative to temperatures elsewhere. That’s a weird claim to make.

  100. Joshua says:

    Jamie –

    . I think you’d have to get them to define exactly what they mean by significant.

    It seems to me that to predict non-significant impact, you have to quantify “significant.” I don’t see why I’d ask someone else how you make that quantification.

    Also, are you sure that corals inhabit waters in the depth range that are quantified in measures of SSTs?

  101. BBD says:

    Ken, I voice no opinion on how the risk to coral reefs will evolve if global warming accelerates to 2C.

    Why not? It it the elephant in the room whose existence you appear to be attempting to deny.

    Jeffh is probably not a paleoclimatologist.

    Are you? Those I have encountered are not sanguine about the ecosystem impacts of AGW.

    Timeline of mass extinction events. The five named vertical bars indicate mass extinction events. Black rectangles (drawn to scale) represent global reef gaps and brick-pattern shapes show times of prolific reef growth. At other times reef growth appears to have been between these extremes, although there were many gaps not associated with mass extinctions and there were intervals of prolific growth in limited geographic regions not indicated here (after Veron 2008)

    * * *

    Veron et al. (2009) The coral reef crisis: The critical importance of <350 ppm CO2

    [quote]Temperature-induced mass coral bleaching causing mortality on a wide geographic scale started when atmospheric CO2 levels exceeded ~320 ppm. When CO2 levels reached ~340 ppm, sporadic but highly destructive mass bleaching occurred in most reefs world-wide, often associated with El Niño events. Recovery was dependent on the vulnerability of individual reef areas and on the reef’s previous history and resilience. At today’s level of ~387 ppm, allowing a lag-time of 10 years for sea temperatures to respond, most reefs world-wide are committed to an irreversible decline. Mass bleaching will in future become annual, departing from the 4 to 7 years return-time of El Niño events. Bleaching will be exacerbated by the effects of degraded water-quality and increased severe weather events. In addition, the progressive onset of ocean acidification will cause reduction of coral growth and retardation of the growth of high magnesium calcite-secreting coralline algae. If CO2 levels are allowed to reach 450 ppm (due to occur by 2030–2040 at the current rates), reefs will be in rapid and terminal decline world-wide from multiple synergies arising from mass bleaching, ocean acidification, and other environmental impacts. Damage to shallow reef communities will become extensive with consequent reduction of biodiversity followed by extinctions. Reefs will cease to be large-scale nursery grounds for fish and will cease to have most of their current value to humanity. There will be knock-on effects to ecosystems associated with reefs, and to other pelagic and benthic ecosystems. Should CO2 levels reach 600 ppm reefs will be eroding geological structures with populations of surviving biota restricted to refuges. Domino effects will follow, affecting many other marine ecosystems. This is likely to have been the path of great mass extinctions of the past, adding to the case that anthropogenic CO2 emissions could trigger the Earth’s sixth mass extinction.[/quote]

  102. BBD says:

    Please provide some evidence of that claim, more than the professional opinion of experts.

    Which is based on a professional career examining the evidence and derives directly from a consequent expert understanding of the evidence.

  103. Joshua says:

    Jamie –

    Let me put this another way: How do you quantify the level of impact of recent warming on coral bleaching? What has the contribution been? What measure do you use?

    Also, what is the relationship between sea surface temps (at the depth measured by sattelites) and the temps in the range of, say, 70′-85′?

  104. Jaime,

    I judge a comment by its content, not by the professional accreditation of the commenter. Best to keep things simple I find.

    There is some merit to this, but if you find yourself at odds with a vaste majority of recognised experts, it’s often wise to take a step back and reflect. Obviously, YMMV.

  105. Jaime Jessop says:

    Joshua,

    Let me put this another way: How do you quantify the level of impact of recent warming on coral bleaching? What has the contribution been? What measure do you use?

    Also, what is the relationship between sea surface temps (at the depth measured by sattelites) and the temps in the range of, say, 70′-85′?

    In answer to the first question, I don’t. I’m not an expert on these matters. You seem to think I am or that I am or more likely that I am assuming that mantle. I am not, I am merely questioning the evidence (or lack of) whereby experts conclude that the global warming secular trend in the oceans is the dominant driver of recent coral reef mortality.

    I’m not sure I understand what you’re getting at with your second question, or what the relevance is.

  106. Jaime Jessop says:

    Oops,

    That should say,

    In answer to the first question, I don’t. I’m not an expert on these matters. You seem to think I am or more likely that I am assuming that mantle. I am not, I am merely questioning the evidence (or lack of) whereby experts conclude that the global warming secular trend in the oceans is the dominant driver of recent coral reef mortality.

  107. Joshua says:

    Jamie –

    With regard to the second question: I would imagine that shorter term fluctuations in climatic patterns might have a stronger impact on SSTs than on temps where the reefs exist, which suggests to me that measuring SST temp trends in association with short term climate fluctuations is of limited utility for determining what impacts the health of corals reefs.

  108. JCH says:

    100% of any El Niño prior to the 15-16 El Niño is anthropogenic. As soon as 2016 is surpassed as the warmest year, it will transition to being 100% anthropogenic. “It’s ENSO” is an utterly worthless argument as long as record warmest years keep happening.

  109. Jaime Jessop says:

    Joshua,

    “With regard to the second question: I would imagine that shorter term fluctuations in climatic patterns might have a stronger impact on SSTs than on temps where the reefs exist, which suggests to me that measuring SST temp trends in association with short term climate fluctuations is of limited utility for determining what impacts the health of corals reefs.”

    If that is the case, why are short term trends in SSTs highly correlated with mass bleaching events? I suggest that subsurface waters where corals live closely follow the short term fluctuations in SSTs during El Nino episodes. We are talking about coral reefs. Most reef building corals live at depths of 18-27 metres which, allowing for tidal ranges, can be effectively considered as ‘surface’ or near surface water.

  110. Joshua says:

    Jamie –

    I am not, I am merely questioning the evidence (or lack of) whereby experts conclude that the global warming secular trend in the oceans is the dominant driver of recent coral reef mortality.

    But part of that evidence they use comes from the study of how ocean temps affect the health of coral I guess t think it’s problematic to your arguments if you are quite unfamiliar with that evidence?

  111. Jaime Jessop says:

    ‘at or above’ 18-27 metres I should have said.

  112. Joshua says:

    Jamie –

    Maybe mass bleaching events occur because coral are less able to recover from the impact of short term fluctuations resulting from short term climatic fluctuations – in which case the longer term, underlying trends are more informative?

  113. Steven Mosher says:

    “It’s even worse for another hack to willfully misinterpret the argument of another hack by introducing the nebulous and somewhat contentious concept of ‘risk’.

    risk is Nebulous?

    thats weird coming from someone who describes temperature rise as “modest”

    this is simple. what would an immodest rise be?

    Hint. the rise is neither modest nor immodest. The rise where corals live is the issue
    and its effect is what matters.

    To snow at 31.5 F a 1F increase is not modest, relative to its survival as snow
    to snow at 23F a 1F increase could be modest, relative to its survival as snow

    So speaking of the temperature increase as “modest” is as another commenter noted
    ‘anthropomorphising”.

    So that we can speak about numbers.

    what is the rise in temperature over the last 100 years or so in the areas where coral live.
    a map would be cool with numbers please.

    otherwise we can talk about immodest temperature rises and get nowhere. rhetoric is fun
    numbers are hard

  114. verytallguy says:

    “what is the rise in temperature over the last 100 years or so in the areas where coral live”?

    As posted above. Not by Jaime, natch.

  115. Chubbs says:

    Nino 3.4 is relatively small region, within 5 degrees of the equator in the eastern Pacific, selected to detect ENSO. Long-term temperature trends are muted in Nino 3.4 due to the large impact of ENSO cycling, so it is misleading to focus on Nino 3.4 temperatures when assessing Coral Reefs.

    The chart below gives a feel for how much stronger enso variability is in Nino 3.4 (5N to 5S, 170W to 120W) vs. the rest of the tropical Pacific and how much weaker overall warming is there.

  116. I have an idea on how to perhaps resolve some of the issues of coral bleaching attribution. There are locations in the equatorial Pacific that are nodal points with respect to the ENSO dipole. Look at places halfway between Darwin and Tahiti and contrast those to maximal ENSO excursion locations?

  117. BBD says:

    I am merely questioning the evidence (or lack of) whereby experts conclude that the global warming secular trend in the oceans is the dominant driver of recent coral reef mortality.

    1/. Modern observational evidence is unequivocal, not ‘lacking’
    2/. Palaeoclimate and fossil evidence strongly supports threat to corals from CO2-forced warming and ocean pH shift

    Just because you don’t understand the topic doesn’t mean that the experts are wrong.

  118. Everett F Sargent says:

    Has this paper been discussed?
    Increasing thermal stress for tropical coral reefs: 1871–2017
    https://www.nature.com/articles/s41598-018-24530-9
    “Tropical corals live close to their upper thermal limit making them vulnerable to unusually warm summer sea temperatures. The resulting thermal stress can lead to breakdown of the coral-algal symbiosis, essential for the functioning of reefs, and cause coral bleaching. Mass coral bleaching is a modern phenomenon associated with increases in reef temperatures due to recent global warming. Widespread bleaching has typically occurred during El Niño events. We examine the historical level of stress for 100 coral reef locations with robust bleaching histories. The level of thermal stress (based on a degree heating month index, DHMI) at these locations during the 2015–2016 El Niño was unprecedented over the period 1871–2017 and exceeded that of the strong 1997–1998 El Niño. The DHMI was also 5 times the level of thermal stress associated with the ‘pre-industrial’, 1877–1878, El Niño. Coral reefs have, therefore, already shown their vulnerability to the modest (~0.92 °C) global warming that has occurred to date. Estimates of future levels of thermal stress suggest that even the optimistic 1.5 °C Paris Agreement target is insufficient to prevent more frequent mass bleaching events for the world’s reefs. Effectively, reefs of the future will not be the same as those of the past.”

    Hughes appears to write quite frequently (via Scholar search last night).
    https://www.coralcoe.org.au/person/terry-hughes
    https://scholar.google.com/scholar?hl=en&as_sdt=0%2C25&q=Global+warming+and+recurrent+mass+bleaching+of+corals&btnG=
    559 citations for a 2017 is mighty impressive, of those citations … 1, 2, 4 are also by Hughes.
    https://scholar.google.com/citations?user=MhJ2LfsAAAAJ&hl=en&oi=sra

    I’m thinking there is some bleaching of this thread by JJ channeling Peter Ridd talking points.

  119. Everett F Sargent says:

    Hughes is from JCU just like Ridd was.

  120. Steven Mosher says:

    ““what is the rise in temperature over the last 100 years or so in the areas where coral live”?”

    I was thinking the Lat Lon

    I can go pull grid cells.. leaving on plane though but may have time tommorrow

  121. Steven Mosher says:

    VTG throw a towel over that chart, there’s an inmodest rise

  122. Everett F Sargent says:

    From “Spatial and temporal patterns of mass bleaching of corals in the Anthropocene”
    http://science.sciencemag.org/content/359/6371/80

    “Inevitably, the link between El Niño as the predominant trigger of mass bleaching (3–5) is diminishing as global warming continues (Fig. 1) and as summer temperature thresholds for bleaching are increasingly exceeded throughout all ENSO phases.”


    Fig. 1 Global warming throughout ENSO cycles.
    Sea surface temperature anomalies from 1871 to 2016, relative to a 1961–1990 baseline, averaged across 1670 1° latitude–by–1° longitude boxes containing coral reefs between latitudes of 31°N and 31°S. Data points differentiate El Niño (red triangles), La Niña (blue triangles), and ENSO neutral periods (black squares). Ninety-five percent confidence intervals are shown for nonlinear regression fits for years with El Niño and La Niña conditions (red and blue shading, respectively; overlap is shown in purple).

  123. Willard says:

    > I am merely questioning the evidence

    Questions may not suffice to have a point, Jaime, and I think you do a bit more than ask questions with this lede:

    The day has come. Scientists are heartbroken. Corals are as good as dead. RIP beautiful coral reefs. (sniff, sniff, *reaches for Kleenex*)

    Or with this auditing move:

    “Any time”? That would imply that mass coral bleaching is occurring randomly regardless of El Nino events. This is clearly double Dutch from the Guardian.

    Even your title presumes a bit more than an interrogative mode.

  124. Steven Mosher says:

    I just read the paper Jamie claimed was behind a paywall. Its not.

    Its’ argument is entirely different than she asserts.

    why am I not surprised.

    lets give her another try.

    Try to give the argument in the paper jamie.

  125. Everett F Sargent says:

    Steven Mosher,

    Paper title and link? TIA
    (I just ‘wasted’ a few minutes backtracking JJ’s posts, so maybe I missed it.)

  126. Everett F Sargent says:

    OK, I think Willard just answered my question.

  127. BBD says:

    Try to give the argument in the paper jamie.

    Much the same as in Veron (2009) (quoted here and totally blanked by JJ).

    Waste of time.

  128. Jaime Jessop says:

    Well hell, it’s so nice to be the focus of attention of so many of you good people on here, but I can’t possibly respond to every commenter, because, you know how it is, I have a life and stuff. So I’ll work backwards from a few.

    Mosher,
    That blog post was over a year ago. Did you ever stop to consider that the paper might have been pay-walled then but isn’t now? Also, if you’d read any of the comments, you’d know that I got access to the paper and you’d understand why I’m arguing what I am. But never mind.

    Willard,
    Hmm, yeah, right.

    Everett,
    “Coral reefs have, therefore, already shown their vulnerability to the MODEST (~0.92 °C) global warming that has occurred to date.”
    Please report the authors of that paper for the offence of anthropocentrism! LOL

    BBD,
    Hmm, yeah, right.

    VTG,
    Do corals live on land as well as in the sea? I didn’t know that. Fascinating.

    Mosher,

    Anthropomorphism is not the same as anthropocentrism. I was accused of indulging in the latter. It’s not the same as anthropogenic either, which you guys seem to see so clearly and unequivocally in global environmental changes.

  129. Everett F Sargent says:

    From … Increasing thermal stress for tropical coral reefs: 1871–2017
    https://www.nature.com/articles/s41598-018-24530-9

    Figure 2. Average annual degree heating month index (DHMI) for 100 coral reef locations, 1871–2017 (grey bars). Black bars mark years with Niño 3.4 index ≥1.0.

  130. Joshua says:

    Steven –

    What is inaccurate about how Jamie characterized the arguments made in that paper?

  131. Everett F Sargent says:

    Same reference …

    Figure 5. Average degree heating month index DHMI (blue) and global land and sea temperature (red) for 10-year periods, 1951–1960 through 2001–2010 and most recent 8-year period, 2011–2017.

    Bye bye

  132. BBD says:

    BBD,
    Hmm, yeah, right.

    Best to say nothing when you have nothing, JJ.

  133. Joshua says:

    Jamie –

    I think you may have missed my comment. I’ll re-post with a bit of editing.

    Maybe mass bleaching events occur because coral are less able to recover from the impact of short term [SST] fluctuations [that you are referencing] resulting from short term climatic fluctuations – in which case the longer term, [subsurface] underlying trends are more informative [as to the long term health of corals].

    [Do short-term climatic fluctuations impact surface and subsurface waters equally?]

  134. Everett F Sargent says:

    JJ,

    You could, of course, at least TRY to stick to the science. It turns out that sticking to the science is almost always the best tactical and strategic approach, or so I have been told. :/

  135. BBD says:

    From Hughes18, emphasis added for JJ:

    We tested the hypothesis that the number of bleaching events that have occurred so far at each location is positively related to the level of postindustrial warming of sea surface temperatures that has been experienced there (fig. S4). However, we found no significant relationship for any of the four geographic regions, consistent with each bleaching event being caused by a short-lived episode of extreme heat (12,19,20) that is superimposed on much smaller long-term warm-ing trends. Hence, the long-term predictions of future average warming of sea surface temperatures (13) are also unlikely to provide an accurate projection of bleaching risk or the location of spatial refuges over the next century.

    In the coming years and decades, climate change will inevitably continue to increase the number of extreme heating events on coral reefs and further drive down the return times between them. Our analysis indicates that we are already approaching a scenario in which every hot summer, with or without an El Niño event, has the potential to cause bleaching and mortality at a regional scale. The time between recurrent events is increasingly too short to allow a full recovery of mature coral assemblages, which generally takes from 10 to 15 years for the fastest growing species and far longer for the full complement of life histories and morphologies of older assemblages (21–24). Areas that have so far escaped severe bleaching are likely to decline further in number (Fig. 2B), and the size of spatial refuges will diminish. These impacts are already underway, with an increase in average global temperature of close to 1°C. Hence, 1.5° or 2°C of warming above preindustrial conditions will inevitably contribute to further degradation of the world’s coral reefs (14). The future condition of reefs, and the ecosystem services they provide to people, will depend critically on the trajectory of global emissions and on our diminishing capacity to build resilience to recurrent high-frequency bleaching through management of local stressors (18) before the next bleaching event occurs

  136. Windchaser says:

    “that the long term secular trend in ocean warming is making corals more vulnerable to bleaching during El Ninos because the AGW ‘little bit on top’ of the much larger and far more rapid increase in temperature due to natural warming is somehow critical”

    Well, yeah. Biological systems do tend to have tipping points.

    My body can comfortably handle a temporary 1C rise in core temperature. The risk of death from this is quite small. But a 6C rise in core temperature will kill me. That’s such a small change in temperature, relative to the 310K of my normal body temperature, but it’s enough.

    The change in health is very non-linear with respect to the change in temperature.

    So, yeah, I think that “little bit on top” of extra warming can be quite important. What is a “modest temperature rise” in one ecological system can be completely devastating in another.

    —> You can’t say “the anthropogenic temperature change seems small to me, therefore it’s unimportant for coral health”.

  137. Everett, Indeed 🙂 That’s why our own research is eventually vindicated, as long as we stick to the physics.

  138. Willard says:

    > Hmm, yeah, right.

    Perhaps I was unclear.

    One does not simply make a point in Mordor just by “asking questions.”

    If you have a point, you make it. Once you make a point, you stick to it. Sticking to your point entails you don’t backtrack to “I am merely questioning the evidence.”

    Hope this helps.

    ***

    What’s your point, again?

  139. verytallguy says:

    Jaime,

    “Do corals live on land as well as in the sea? I didn’t know that. Fascinating.”

    Well, Jaime, I couldn’t find the SST quickly for the tropics. But as you had provided precisely no data, I thought that was better than nothing.

    So, as the combined data isn’t convincing, how about you share the SST data which you have doubtless already reviewed to come to your conclusions?

  140. Willard says:

    > if you’d read any of the comments, you’d know that I got access to the paper and you’d understand why I’m arguing what I am. But never mind.

    I mind, for here’s what Mosh said:

    I just read the paper Jamie claimed was behind a paywall. Its not.

    Its’ argument is entirely different than she asserts.

    What is the argument made in the paper, and what is Jaime’s argument?

    Not sure how she could argue by just asking questions or Mosh with proofs by assertion, but here we go.

  141. verytallguy says:

    Ah yes, here we go. H/t Everett above

  142. BBD says:

    What is the argument made in the paper, and what is Jaime’s argument?

    Possibly JJ is attempting to peddle the difference between just the first paragraph of the Hughes18 quote above and the quote in its entirety.

  143. Jaime Jessop says:

    Joshua,

    Apologies. You do at least seem willing to engage reasonably with the actual arguments. Mass bleaching/global bleaching events are clearly well defined and documented since the early 1980s, coincident with three very notable El Nino episodes: 1982/83. 1997/98 and 2015/16, though, as noted, occurring technically outside El Nino conditions in 2017. Mass bleaching also happened around 2010 I believe, coincident with the Modoki El Nino which peaked that year. Clearly, heat stress caused by warmer waters circulated globally during intense El Ninos is the trigger for mass bleaching events. This may not be the only reason why corals across the globe have bleached when stressed by these warmer waters. There are numerous other environmental stressors, both natural and anthropogenic, which may have contributed to coral bleaching, operating inside as well as outside the El Nino window, which may have contributed to a decrease in the resilience of corals, perhaps making them more susceptible to recurrent bouts of thermal bleaching. The consensus explanation for these mass bleaching events is that the secular ocean global warming trend is the main thing which has rendered corals less resistant to thermal bleaching during El Ninos. I’m not convinced. The paper I referenced in my blog post claims that bleaching events have become more frequent and more severe since 1980 not because, since 1980, we have seen a quite remarkable series of three very powerful El Ninos, with others less notable in between, but simply because global warming has made the oceans just that little bit hotter than they were 50, 60, 100, 150 years ago – not mentioning of course that pre-1950 oceanic warming cannot be reliably attributed to anthropogenic causes. I’m not convinced.

  144. Willard says:

    > I’m not convinced.

    Compare and contrast with this fall:

    Just like the shrinking Arctic sea-ice measured over 36 years which was supposed to be the death knell for polar bears, corals are now deemed to be in imminent danger of extinction using 36 years of coral bleaching observations and only 4 recorded instances of mass bleaching – in 1983, 1998, 2010 and 2016. Yes, the time between events has shortened dramatically – but they only have 4 data points to work with! However, this appears to be sufficient to pronounce gravely upon the future survivability of corals in the dreaded Anthropocene, i.e. corals which survived the extinction of the dinosaurs, which survived the rapid 4C global warming of the PETM, which have survived millions of years on a hotter Earth when no ice existed at either pole, are done for because the planet warmed 0.6C after 1980 and we had a few very powerful El Ninos which bleached them.

    From just asking questions there is a switch to incredulity, and from incredulity the editorial content of the post (along its title) cascade into incredibilism.

  145. BBD says:

    And more blanking from JJ.

  146. Willard says:

    Let’s try not to pile on and to stick to the commitments, i.e. the claims, the arguments, the evidence, etc. It’s been a while since I played #ButCorals, e.g.:

    Not sure how the claim that corals survived the extinction of the dinosaurs counters the one according to which the time between recurrent events is increasingly too short to allow a full recovery of mature coral assemblages.

  147. Jaime Jessop says:

    Pile on, do, like water piles on to a duck’s back.

    If anyone is interested in reading a balanced assessment of the reasons for coral bleaching, here it is. Not a single mention of emissions reductions or the Anthropocene. How terribly boring.

    http://www.marinebiology.org/coralbleaching.htm

  148. The Very Reverend Jebediah Hypotenuse says:


    Global climate change may play a role in the increase in coral bleaching events, and could cause the destruction of major reef tracts and the extinction of many coral species.

    Maybe your reference doesn’t mention emissions reductions or the Anthropocene because that’s not part of “marine biology”?

    And because some things are just too obvious to readers who aren’t attempting to make a desperate argument from incredulity?

    How terribly boring indeed.

  149. Willard says:

    > Pile on, do

    My request has not been made for your own sake, dear Jaime. I take it that poisoning AT’s well would be a win for you. Come what may, sooner or later you’ll have to face the fact that your incredulity fails to take timescales into account. Speed (or acceleration) of warming matters:

    https://andthentheresphysics.wordpress.com/2019/02/17/only-connect/

  150. Joshua says:

    Jamie –

    Clearly, heat stress caused by warmer waters circulated globally during intense El Ninos is the trigger for mass bleaching events.

    That doesn’t seem clear to me from what you’ve argued, as the argument has also been made that the underlying trend of warming increases the magnitude of damage from El Ninos. You seem to be arguing there is some clear delineation of the effects of the different phenomena, but without, as near as I can tell, articulating an argument from how they would be delineated. This goes back to my question to you about how you quantify significance.


    but simply because global warming has made the oceans just that little bit hotter

    That doesn’t seem to me to be the argument made. My reading is that the argument has been made that the two phenomena work in conjunction.

    The logic works both ways: Just because other factors (natural, other anthropogenic factors ) might be contributing to more, and more extensive bleaching events doesn’t seem sufficient to me to discount the effect of anthropogenically caused warming – especially if there is a longer term trend of warming that runs across the short term events of exceptional warming.. And I’m wondering, with still no one having addressed the issue, whether there might be reason to believe that long term trends in coral health would be more closely tied to trends in subsurface temps than the impact of short-term dramatic fluctuation in surface temps – since the cross section measured by sattelites is quite shallow and coral exist considerably deeper (even if they exist close to the surface relative to the mean depth of oceans).

  151. verytallguy says:

    How *very* bizarre.

    Jaime:

    If anyone is interested in reading a balanced assessment of the reasons for coral bleaching, here it is. Not a single mention of emissions reductions or the Anthropocene. How terribly boring.

    Reading the cite reveals this “balanced” assessment to be far more alarming than the OP, threatening mass extinctions and the like left right and centre. Just for instance:

    Global climate change may play a role in the increase in coral bleaching events, and could cause the destruction of major reef tracts and the extinction of many coral species

    and

    A conservative temperature increase of 1-2 degrees C would cause regions between 20-30 degrees N to experience sustained warming that falls within the lethal limits of most reef-building coral species.

    It’s the antithesis of Jaime’s position.

    This is getting seriously weird.

  152. Joshua says:

    Jamie –

    I think that Willard’s point is key to what I’m asking you to address. You do seem to be making an argument from incredulity, which is further complicated by your professed lack of expertise in a range of fields that are very closely related to the questions at hand. It seems to me that the combination of incredulity with lack of expertise is a problematic convergence.

    Seems to me that the remedy to that problem is for you to provide an explanation for what magnitude of impact you think there is from longer term trends of warming and how that can be distinguished from shorter term discrete impact from discrete, short-term events. Again, that beings me baci to your use of the term “significant.”. Using that term without quantifying wha it means seems to me to be a way to slip into an argument from incredulity.

    Does that make sense?

  153. The Very Reverend Jebediah Hypotenuse says:


    This is getting seriously weird.

    Compared to what?
    https://delingpoleworld.com/tag/jaime-jessop/

  154. Jaime Jessop says:

    Yes, sorry VTG, it does require a balanced point of view to read that article and extract from it anything useful.

  155. Everett F Sargent says:

    RE: “If anyone is interested in reading a balanced assessment of the reasons for coral bleaching, here it is. Not a single mention of emissions reductions or the Anthropocene. How terribly boring.”

    http://www.marinebiology.org/coralbleaching.htm

    Site sez ,,, “Copyright 1998-2013” but the most recent reference is a 1996 publication or three (23 years old).

    So let’s limit this discussion to peer reviewed published on, or before, 1996. Because papers from 2017-2018-2019 are all to recent to have stood the scientific test of time. This follows from the logical fallacy of … wait for it … Too New To Be True.

  156. Jaime Jessop says:

    No Joshua, that doesn’t make much sense I’m afraid. Actually, yes, it does, thinking about it, but never mind. Nice chatting.

  157. Jaime,
    The point is that your own sources suggest that anthropogenically-driven climate change is playing a significant role in coral bleaching, and will play an increasing role; if global warming continues, Coral mortality could exceed 95% regionally with species extirpation and extinctions.. In what way does this source support what you seem to be suggesting (anthrogenically-driven climate change is not a significant cause of coral bleaching)?

  158. Joshua says:

    Jamie –

    If you want to come back and explain the errors in my understanding, I’d appreciate the input. Of course, there’s no guarantees that I’ll be able to understand your explanation, but it might be worth a shot.

  159. Jaime Jessop says:

    Joshua,

    I provided you with a very clear and unambiguous statement and your response was basically waffle. I’m all for discussion, but I do expect meaningful replies to a simple statement, which should be interpreted in the context of what I wrote in totality, not presented in isolation for you to try and dissect. It’s a waste of both our time.

    “Clearly, heat stress caused by warmer waters circulated globally during intense El Ninos is the trigger for mass bleaching events.

    That doesn’t seem clear to me from what you’ve argued, as the argument has also been made that the underlying trend of warming increases the magnitude of damage from El Ninos. You seem to be arguing there is some clear delineation of the effects of the different phenomena, but without, as near as I can tell, articulating an argument from how they would be delineated. This goes back to my question to you about how you quantify significance.”

  160. izen says:

    It seems growing coral is a net source of atmospheric CO2, something to do with shifting the chemical gradients when it makes CaCO3.
    So at least the reduction and extinction will be a negative feedback with a net increase in ocean CO2 sequestration.
    Especially if it could be replaced with large algae blooms that could be relied upon to sink rapidly to anoxic depths..

  161. Jaime Jessop says:

    Ken, like I said, you have to have a balanced viewpoint to read it and interpret it for what it is – a down to earth, balanced assessment of the possible causes of coral bleaching. Unfortunately people here just go straight to the bits which appear to confirm their bias, but which don’t, if you read the entire piece with an open mind.

  162. Joshua says:

    Jamie –

    Sorry for the waffling.

    I thought I responded directly to your statements. I quoted the sections I was responding to, to the sections where I thought your arguments problematic.

    But regardless, let me try again.

    You said that clearly, El Ninos trigger bleaching events. It seems to me that to make that attribution meaningful, you need to distinguish the contribution of El Nino events from the contribution of an underlying warming trend.

    Do you disagree?

  163. Jaime,
    The conclusion to the article seems pretty unequivocal. There are clearly other stressors, but it seems pretty clear that a vaste majority of experts (including the authors of that article) regard anthropogenically-driven warming as a major one.

  164. Jeffh says:

    Jaime writes, “Best to keep things simple I find”.

    No kidding. Her arguments singularly fail to understand the importance of temporal scales in evolutionary responses. Look at Bjorn Lomborg; he believes that polar bears will evolve into terrestrial omnivores in one or two generations if the summer Arctic ice disappears within the next half century. This is beyond funny. Jaime is cut from the same cloth. Contrarians write as if 50 years is a long time and a century is forever. To them this is deep time. In evolutionary terms it is the blink of an eye. Warming that was probably responsible for the mass extinction at the Permian-Triassic boundary (known as the ‘Great Dying’) elapsed over 100-200 centuries. Humans are compressing the same rate of warming into less than 2 centuries. Something has got to give.

    The inability of many people to truly understand the importance of scale and to be able to tease apart stochastic and deterministic processes is telling. And to answer Jaime’s comment, no, I am not a paleoclimatologist. I am a population/evolutionary ecologist. Jaime, unfortuneately, is neither. It shows.

  165. Jaime Jessop says:

    “So let’s limit this discussion to peer reviewed published on, or before, 1996.”

    Ah, yes, forgive me. The science of coral bleaching has changed since this was written, obviously We’ve had two more powerful El Ninos which have bleached even more corals and catastrophism has displaced sober reflection upon causes. 2018 papers are sooo much better informed.

  166. Jaime Jessop says:

    Joshua, you seem not to be able to comprehend the meaning of the word ‘trigger’. Corals get bleached, globally, during powerful El Ninos. El Nino is global. Bleaching is global, demonstrably coincident with El Nino events on several occasions. If El Ninos are not triggering global bleaching events, what is? Sporadic and unexplained accelerations in the ocean global warming trend which just ‘happen’ to occur when El Ninos do?

  167. Jaime,
    Did you read your own source?

    Prior to the 1980s, most mass coral moralities were related to non-thermal disturbances such as storms, aerial exposures during extreme low tides, and Acanthaster outbreaks. Coral bleaching accompanied some of the mortality events prior to the 1980s during periods of elevated sea water temperature, but these disturbances were geographically isolated and restricted to particular reefs zones. In contrast, many of the coral bleaching events observed in the 1980s occurred over large geographic regions and at all depths.

    So, why has bleaching become more global since 1980? Could it be that ENSO events have somehow changed in character since 1980, or could it be that the underlying anthropogenically-driven warming trend means that post-1980 El Ninos can enhance sea temperartures so that the impact is now global, rather than local (i.e., local variability is high enough that without a smaller secular trend you could impact some reefs, but not all before 1980, but post-1980 the underlying trend means that these events cross the threshold globally)?

  168. BBD says:

    Conclusion

    If a global warming trend impacts on shallow tropical and subtropical seas, we may expect an increase in the frequency, severity and scale of coral reef bleaching. Coral mortality could exceed 95% regionally with species extirpation and extinctions. A conservative temperature increase of 1-2 degrees C would cause regions between 20-30 degrees N to experience sustained warming that falls within the lethal limits of most reef-building coral species. In conjunction with sea temperature rise would be a sea level rise, and it has been suggested that sea level rise would suppress coral growth or kill many corals through drowning or lower light levels.

  169. BBD says:

    If El Ninos are not triggering global bleaching events, what is?

    Will you please read. Your confusion has been addressed, multiple times now.

  170. verytallguy says:

    Jaime,
    Did you read your own source?

    I’ve been hanging around climate blogs for a long time ( perhaps too long) but I honestly think I’ve never been quite so nonplussed as I am at Jaime on this thread.

    That source absolutely and unequivocally demolishes the position Jaime takes. Yet she insists it supports her.

    Weird. Bizarre. Preposterous. Fantastical. I’m running out of adjectives.

  171. BBD says:

    Apparently you have to have a balanced viewpoint, vtg…

  172. izen says:

    @-BBD
    “Apparently you have to have a balanced viewpoint, vtg…”

    You should also read the entire piece with an open mind and avoid going straight to the bits which appear to confirm your bias.
    .
    .
    .
    .
    .

  173. Joshua says:

    Jamie –

    Sorry for my lacking in comprehension.

    You seem to be saying that El Ninos are a discrete trigger of bleaching events, and as near as I can tell others are arguing that the causation is multifactorial and that an underlying trend of eating is one of those factors. So I’m trying to better understand your argument. I appreciate your patience.

    I’m wondering on what evidence basis you single out El Ninos as a trigger?

    demonstrably coincident with El Nino events on several occasions.

    Yes, but that doesn’t prove causation – particularly when we consider the frequency and magnitude of El Nino-associated bleaching events. El Ninos might be one of the “triggers” along with other triggers, such as increased baseline temperature. An association with El Ninos doesn’t in itself establish El Ninos as the discrete trigger – as you seem to be saying. And perhaps a particular El Nino of X magnitude might cause Y degree of bleaching with one baseline temperature, but Y + 1 magnitude at X + 1 baseline – in which case the attribution of “cause” of bleaching becomes more complicated. As near as I can tell, you seem to acknowledge this complication with other potential influences on bleaching causation, but not with an underlying trend of warming.

    . If El Ninos are not triggering global bleaching events, what is?

    I’m not suggesting that they aren’t a trigger. I’m questioning you about your attribution of bleaching to El Ninos to the exclusion of the contribution of an underlying warming trend, and asking you in what evidence you base that attribution?

    . Sporadic and unexplained accelerations in the ocean global warming trend which just ‘happen’ to occur when El Ninos do?

    No. That isn’t what I was suggesting.

    I’m wondering about the arguments from others that an increase in the underlying base temps might factor into the “triggering” (which directly connected to quantification of frequency and magnitude) of bleaching – and what evidence you have for your attribution of bleaching to El Ninos to the exclusion of that other potential causal mechanism.

    It seems to me I’ve asked the same basic question multiple times now, without getting an answer. Maybe I’m not able to explain myself in a way that can be understood (maybe I just don’t understand the material well enough to even develop a clear question).

    The basic question is what evidence do you use to delineate the contribution of El Ninos from other causal factors in bleaching events (and specifically the potential of underlying warming to cause bleaching, and to increase bleaching frequency and magnitude)?

    I’m asking you for the evidence you use.

  174. Joshua says:

    Heh. Commenting on my phone. Eating = warming.

  175. izen says:

    At the risk of misrepresenting…

    I think the form of the argument JJ is presenting is the same as the one used to reject any ‘significant’ role for AGW in hurricane impacts. There are still too few events over the observed period to detect any SIGNIFICANT change attributable to AGW because any observed increased intensity and rainfall could still be within the range of ‘Natural’ variation.

    Two problems with this;
    As with the hurricane version there is a credible, observable, physical/biological process that links storm intensity and coral bleaching with temperature.
    As with major storms the bleaching numbers are now edging over into significance, the underlying role of the secular trend is beginning to emerge from the accumulating data.

    It will always be possible to define/reify a distinction between a specific extreme event and any underlying trend and claim the specific event was the primary cause. With at least the tacit implication that all else is secondary and not significant.
    But it is a tactic subject to diminishing returns. It is already failing in the scientific mainstream to have any traction. Both storm intensity and coral bleaching are now accepted to have a discernible shift in magnitude and incidence due to the secular trend.
    As is obvious here, it is not persuasive to those interested and informed. Or alarmists and activists in contrarian parlance.
    Soon it will be an argument that will struggle to convince those making it…

  176. Maybe JJ will understand this view.

    ENSO is forced by long-period tidal cycles and so has a limited (yet strong) impact. Global warming however has no limit. It’s the same concern as global sea-level rise versus diurnal tidal cycles, we don’t have to worry about the latter as it is a known quantity.

  177. Jaime Jessop says:

    Good grief, you guys just love to re-interpret what commenters say in order to suit your own arguments. Time and time again, words I never said have been put into my mouth. Here’s a classic example:

    VTG:-

    “I’ve been hanging around climate blogs for a long time ( perhaps too long) but I honestly think I’ve never been quite so nonplussed as I am at Jaime on this thread.

    That source absolutely and unequivocally demolishes the position Jaime takes. Yet she insists it supports her.

    Weird. Bizarre. Preposterous. Fantastical. I’m running out of adjectives.”

    What I said was:-

    “If anyone is interested in reading a balanced assessment of the reasons for coral bleaching, here it is.”

    For the benefit of those whose English comprehension is not even up to the standard of bickering on blog post threads, this means, ‘I think this is a sober, unbiased, balanced assessment’. It does NOT mean ‘This supports my argument’. My mistake was to present a non-biased, balanced, scientific assessment to an audience whose bias is pretty extreme.

    Anyway, I’m through ‘poisoning the well’ (according to a particularly poisonous individual) at this blog, on this increasingly hostile, weird, bizarre and preposterous thread where people can’t read my comments without injecting their own interpretive fairytales and where they cannot read a scientific paper without leaping to the conclusion that it supports their own biased viewpoint. But I’ll leave with this parting swipe, also for the benefit of those who have difficulty with English comprehension:

    “Global climate change MAY play a role in the increase in coral bleaching events, and COULD cause the destruction of major reef tracts and the extinction of many coral species. . . .

    NATURAL disturbances which CAUSE DAMAGE to coral reefs include violent storms, flooding, high and low temperature extremes, EL NINO SOUTHERN OSCILLATION (ENSO) events, subaerial exposures, predatory outbreaks and epizootics.

    Coral reef bleaching is a common stress response of corals to many of the various disturbances mentioned above. Beginning in the 1980s, the frequency and widespread distribution of reported coral reef bleaching events increased. Widespread bleaching, involving major coral reef regions and resulting in mass coral mortality has RAISED CONCERNS about LINKAGE of the events to global phenomenons including global warming or climate change AND increased UV radiation from ozone depletion. . . . .

    As coral reef bleaching is a general response to stress, it can be induced by a VARIETY of factors, alone or in combination. It is therefore difficult to UNEQUIVOCALLY IDENTIFY THE CAUSES for bleaching events. . . . .

    MOST of the coral reef bleaching events of the 1980s occurred during years of large-scale ENSO activity. . . . .

    Global warming, ALONG WITH ENSO events, change sea water temperatures.

    IF a global warming trend impacts on shallow tropical and subtropical seas, we MAY expect an increase in the frequency, severity and scale of coral reef bleaching. Coral mortality COULD exceed 95% regionally with species extirpation and extinctions.”

    Absolutely nowhere in this article does the author state that the cause of the mass coral bleaching events which started in the 1980s IS the general warming of the oceans. The author definitely DOES state that ENSO events are a direct cause of bleaching, among a host of other stressors. THREE super El Ninos after 1980, NONE prior to that,in the observational ONI database going back to 1950. The last documented super El Nino was in 1876-78. Just think about that. The article does NOT support my argument that ENSO has been the main cause, however, nor does it definitely support the argument that global warming is the main driver behind mass coral bleaching since the 1980s.

    You lot really do need to grow up, stop sniping, and learn how to debate rationally and calmly with those who do not share your opinions.

    Bye.

  178. Joshua says:

    Jaime –

    The article does NOT support my argument that ENSO has been the main cause, however, nor does it definitely support the argument that global warming is the main driver behind mass coral bleaching since the 1980s.

    What is the evidence you rely on that does support that argument of yours? Seams to me that in order to make your argument vslid you’d need to quantify the contributions of different variables. I don’t see where you’ve done that.

    Do you have evidence that El Ninos don’t effectively act as a mediator in the relationship between baseline temps and bleaching events?

  179. Joshua says:

    Jaime –

    I’ll ask again.

    The basic question is what evidence do you use to delineate the contribution of El Ninos from other causal factors in bleaching events (and specifically the potential of underlying warming to cause bleaching, and to increase bleaching frequency and magnitude)?

    I’m asking you for the evidence you use.

    Lest I make an incorrect conclusion, maybe you’ll clarify. Does your lack of an answer to my question mean that you aren’t basing your conclusion that El Ninos “has been the main cause” of [increases in frequency and distribution of?] bleaching on evidence that El Ninos are the main cause of [increases in frequency and widespread distribution of] bleaching?

  180. Steven Mosher says:

    “Mosher,
    That blog post was over a year ago. Did you ever stop to consider that the paper might have been pay-walled then but isn’t now? Also, if you’d read any of the comments, you’d know that I got access to the paper and you’d understand why I’m arguing what I am. But never mind.”

    Jamie, So the facts changed and you didnt do an update.

    Shit even Anthony does that.

    As for your “argument” it’s your job to make it clear and coherent, you havent

  181. verytallguy says:

    Jaime

    Coral mortality could exceed 95% regionally with species extirpation and extinctions

    No quantity of your all caps can contradict these conclusions of the citation, which beyond all comprehension, you still claim supports you.

    Any vestige of logic has departed your argument. Reasonable dialogue is quite impossible in such circumstances.

  182. I’ve just realised that the article we’re discussing was written in 1998. I did a search for something more recent and found this, which says

    Climate change is warming oceans and causing them to remain hotter during the summer months (4). This warming is one of many threats corals are facing and is the cause of recent bleaching events (2).

  183. Ken Fabian says:

    The past ability of much reduced coral populations to survive climate changes, and re-establish at large scales when conditions stabilise is true enough, although those were with much less rapid changes than are currently occurring. But I can see that enough remnant reefs and reef species might survive to establish elsewhere – enough to spawn and re-seed other locations. But I think they will be temporary locations, likely to be lost again locally as conditions become viable in new locations, only to pass beyond viable again as that warming water trend continues.

    They may not all go extinct but existing, long lived reefs at large scale, that we know and don’t want to lose can and likely will be lost. And some coral species will very likely will become permanently extinct, along with reef dependent fish and other species, even if the potential, should climate stabilise, to re-establish is still there. This is not the same thing as corals being resilient.

  184. Everett F Sargent says:

    “I’ve just realised that the article we’re discussing was written in 1998.”

    I didn’t even read it, mainly because all those publication dates started with 19xx, a quick search on 200, 201, then 1999 then 1998 then 1997 then finally 1996 and B-I-N-G-O. File that one under; How old is information on a website anyways?

    Not that there’s anything wrong with that … old information on a website, that is.
    https://en.wikipedia.org/wiki/The_Outing_(Seinfeld)

  185. Willard says:

    > For the benefit of those whose English comprehension is not even up to the standard of bickering on blog post threads, this means, ‘I think this is a sober, unbiased, balanced assessment’. It does NOT mean ‘This supports my argument’.

    Yet that sober, unbiased, balanced assessment supports the argument made in the paper Jaime was criticizing. This might be the moment where the goalpost is moved toward communication issues.

    It’s not science, but it’s important.

    ***

    > Anyway, I’m through ‘poisoning the well’ (according to a particularly poisonous individual) at this blog, on this increasingly hostile, weird, bizarre and preposterous thread where people can’t read my comments without injecting their own interpretive fairytales and where they cannot read a scientific paper without leaping to the conclusion that it supports their own biased viewpoint.

    Thank you for the kind words. In return, let’s review the bidding. We have a post:

    – raising concerns about a paper that has not been read at the time;
    – based on personal incredulity;
    – disregarding timescales;
    – decorated with the usual CAGW meme;
    – portrayed as “mere questioning”;
    – not clarified (no real claim, no real target) after many requests;
    – not padded with complementary evidence;
    – supported with a citation that bolsters the criticized paper;
    – transformed into the famous “it’s not science, but it’s important”

    No wonder we’re witnessing that Cartmanesque sortie.

  186. Steven Mosher says:

    well now that we know jamie has access to the paper, theres no excuse for her inability to give us what the argument is.

    her unwillingness to do it is now more understandable.

    sidebets, what excuse will she give for running from this debate.

  187. Since Jaime appears to have left, maybe we can move on and stick to the topic of coral reefs.

  188. Steven Mosher says:

    attp,

    as i understand it, its the symbiot that is the issue. maybe geoff can explain the basics

  189. Willard says:

    OT, but worth it:

  190. Hyperactive Hydrologist says:

    Here is an interesting paper Eakin et.al 2010 about bleaching of Caribbean Corals in 2005. From the discussion:

    Unlike many past Caribbean bleaching years, strong tropical climate forcing was only a minor driver of Caribbean SSTs in 2005. In their analysis of temperature anomalies across the tropical North Atlantic in 2005, Trenberth and Shea [26] indicated that half of the warming (0.45°C of the 0.9°C anomaly vs. a 1901–1970 baseline) was attributable to monotonic climate change, while only 0.2°C was attributable to the weak 2004–05 El Niño, and even less to the Atlantic Multi-decadal Oscillation (<0.1°C). Despite the lack of strong tropical forcing, 2005 fell among the warmest years on record [11]. NOAA’s Extended Reconstructed SST product [27], [28] showed that average ocean temperatures during the July-October period for the Caribbean exceeded temperatures seen at any time during the prior 150 years (Figure 4). Anticipated future warming of ocean waters [29] is expected to increase the likelihood of future Caribbean bleaching events [30].

    From the abstract of the Trenberth and Shea 2006 paper:

    [1] The 2005 North Atlantic hurricane season (1 June to 30 November) was the most active on record by several measures, surpassing the very active season of 2004 and causing an unprecedented level of damage. Sea surface temperatures (SSTs) in the tropical North Atlantic (TNA) region critical for hurricanes (10° to 20°N) were at record high levels in the extended summer (June to October) of 2005 at 0.9°C above the 1901–70 normal and were a major reason for the record hurricane season. Changes in TNA SSTs are associated with a pattern of natural variation known as the Atlantic Multi‐decadal Oscillation (AMO). However, previous AMO indices are conflated with linear trends and a revised AMO index accounts for between 0 and 0.1°C of the 2005 SST anomaly. About 0.45°C of the SST anomaly is common to global SST and is thus linked to global warming and, based on regression, about 0.2°C stemmed from after‐effects of the 2004–05 El Niño.

    So 0.45°C of the 0.9°C anomaly in 2005 is common to global SST as a result of global warming, with 0.2°C from El Niño and 0-0.1°C due to AMO.

  191. Chubbs says:

    The NOAA 4-month coral reef heat stress outlook has worsened in the past month or two, now not far from outlooks in early March 2016+17.

    https://coralreefwatch.noaa.gov/satellite/bleachingoutlook_cfs/archive_webpage/outlook_icwk20190303.php

  192. Dave_Geologist says:

    I tuned out during the Gish Gallop. When it’s coming so thick and fast it’s probably copy-pasting a prepared script anyway, likely written by someone else. So it’s, shall we say, optimistic to expect to get any traction.

    From a geologist’s perspective we know three things about coral reefs:

    1) They’ve been around a long time, although not the same corals. The various types of corals we’ve had through time are as unrelated to each other as fish, reptiles and mammals.

    2) They go extinct in major climatic crises, although sometimes they can migrate if the temperature is raised slowly enough.

    3) It takes millions of years for a new set of reef-forming corals to evolve from non-reef-forming ancestors. In the hiatus you sometimes get low mounds of other colonial organisms, which look like reefs when you see them fossilised in cliffs. But that’s thousand of years’ worth of mounds stacked on top of each other. At any one time, they only rose a few feet above the seabed. And they grow by trapping mud so are not good fish nurseries. One of my long-ago colleagues summarised the topic of his PhD on Waulsortian mud-mounds as “When is a reef not a reef? When it’s in the Carboniferous” (he had the exciting task of visiting dozens of quarries to determine whether, in life, the mounds were a few feet high or only a few inches high).

    Only once have non-corals (rudist bivalves) filled the gap and made proper reefs. That was in the hothouse world of the Cretaceous, when corals were driven out of equatorial regions and restricted to temperate zones. So maybe it’s not all bad news. Maybe there will be reefs off New York some day. Once they’ve had a few thousand years of stable climate to grow, and assuming their larvae are not deterred by anti-fouling paint. Actually a decent marine transgression would help. Well developed reefs, whether on continental margins or volcanic islands, didn’t grow from deep. They formed in shallow water, and grew upwards as relative sea level rose. Abandoned skyscrapers should make a great substrate.

    This reference is somewhat out of date so will not benefit from recent DNA data, but makes the point: The Palaeozoic corals, I: origins and relationships. You have to wait until some group of sea anemones evolves hard parts and fills the ecological gap. Solitary deep water corals don’t migrate to fill the gap, because they’re (duh!) solitary and live in deep water without the benefit of zooxanthellae, so don’t need sunlight and indeed may be harmed by it.

    They are not considered to have had a skeletonized common ancestor, but they may have arisen as separate skeletonization events from the same broad group of anemones, represented by the living Zoanthiniaria. The Rugosa are not considered to be ancestral to the Scleractinia. The latter, together with the Permian Numidiaphyllida, are considered to have evolved through skeletonization events among a group of anemones derived from the Actiniaria/Corallimorpharia, a member of which also gave rise to the Kilbuchophyllida in the Ordovician.

  193. verytallguy says:

    Fascinating Dave_Geologist, thank you.

    Forgive my ignorant questions: Reef-building corals have been of different classes through time, right? Are there different classes extant today, or are they all now of the same class?

  194. “What paper/coral/proxy data are you referring to, and what meaning do you attribute to it?”

    Following up on this question: This is referring to papers on the Unified ENSO Proxy.

    McGregor, S., A. Timmermann, and O. Timm. “A Unified Proxy for ENSO and PDO Variability since 1650.” Clim. Past 6, no. 1 (January 5, 2010): 1–17. https://doi.org/10.5194/cp-6-1-2010.

    The increase is the variance after 1880 may be attributable to the Krakatoa eruption, which likely perturbed the Indonesion flowthrough by creating a larger island in the Sunda Strait https://tos.org/oceanography/assets/docs/29-2_susanto.pdf

    “ITF’s total volume transport and heat and freshwater fluxes are known to impact both the Pacific and Indian Oceans. In addition, the ITF modulates climate variability by altering air-sea exchange, sea surface temperature, and regional precipitation patterns over many time scales, and it possibly influences the El Niño-Southern Oscillation (ENSO) and Asian-Australian monsoon climate
    phenomena (e.g., Godfrey, 1996; Schneider, 1998; Bryden and Imawaki, 2001; T. Lee et al., 2002; Aldrian and Susanto, 2003; T. Lee and McPhaden, 2008; Tokinaga et al., 2012; Sprintall et al., 2014). In the last two decades, ITF transport increased significantly (Sprintall and Revelard, 2014; Susanto and Song, 2015), increasing the Indian Ocean heat content, which may have strong impacts on global
    climate (S-K. Lee et al., 2015; Reed, 2015).”

  195. Dave_Geologist says:

    The reef-forming corals are all Scleractinia vtg. So nominally one Order. However the view in the oughties, which may have left a memory trace in your mind if you read about it in an article, was that the Scleractinia are polyphyletic like monkeys (New World and Old World Monkeys share a common ancestor so far back that the group comprising descendants of that ancestor includes species which are not classed as monkeys). Convergent evolution has led to the same bodyplan; the same was thought about corals. From a 2003 review The evolution of modern corals and their early history:

    Scleractinians are a group of calcified anthozoan corals, many of which populate shallow-water tropical to subtropical reefs. … Scleractinia stands out as one of the few orders of calcified metazoans that arose in Triassic time, long after a greater proliferation of calcified metazoan orders in the Paleozoic. … The idea that Scleractinia evolved from older Paleozoic rugose corals that somehow survived the Permian mass extinction persists among some schools of thought. Paleozoic scleractiniamorphs also have been presented as possible ancestors. The paleontological record shows the first appearance of fossils currently classified within the order Scleractinia to be in the Middle Triassic. These earliest Scleractinia provide a picture of unexpectedly robust taxonomic diversity and high colony integration. Results from molecular biology support a polyphyletic evolution for living Scleractinia and the molecular clock, calibrated against the fossil record, suggests that two major groups of ancestors could extend back to late Paleozoic time. The idea that Scleractinia were derived from soft-bodied, “anemone-like” ancestors that survived the Permian mass extinction, has become a widely considered hypothesis. … It states that different groups of soft-bodied, unrelated “anemone-like” anthozoans gave rise to various calcified scleractinian-like corals through aragonitic biomineralization. Although there is evidence for this phenomenon being more universal in the mid-Triassic interval, following a lengthy Early Triassic post-extinction perturbation, it appears to have occurred at least three other times prior to this interval

    The Palaeozoic corals were different and unrelated, and the other reference suggests there are up to five independently evolved Orders, although we don’t have the benefit there of DNA evidence. Which would have been relatively new in 2003, so there have probably been some advances since then re the Scleratinia. Basically, “coral” is a bucket term for whatever anemone-derived critter was building reefs at the time.

    There are also octocorals today (Alcyonaria), which are generally soft corals (although the gorgonians are mineralised, and some Scleractinia are soft IIRC). Confusingly, the octocorals were historically classified into four Orders, presumably because without the constraints of reef-building they’ve adopted a huge variety of forms and spread into numerous ecological niches. We now know they’re all related, with a common ancestor back in the mid-Palaeozoic. It’s just occurred to me that their eight-fold symmetry would be a disadvantage compared to six-fold when it comes to stacking together in reefs – perhaps that’s why they’ve never filled that niche. Stephen Jay Gould would have considered that a really cool example of contingency. Some ancestor back in the Ediacaran took on eight-fold symmetry (an obvious thing to do by playing with Hox genes, split and split again), and a career in reef-building was ruled out for evermore.

    It’s probably not that hard to mineralise – the soft corals, like sponges and anemones, contain sclerites or spicules in the skin, like the animal equivalent of studded leather armour or chain mail. You just have to join them up. But making a success of reefbuilding obviously requires more than just that. One factor is no doubt the resources required to build a skeleton. Modern corals need their zooxanthellae to do it. The early Triassic gap was, of course, the time when equatorial waters were so hot they had no fish, and the equatorial land had no reptiles. The abstract hints at some failed earlier attempts to establish reefs, but I’ve not had time to read the paper.

  196. verytallguy says:

    Thanks Dave, appreciate that.

  197. Willard says:

    Perhaps, Dave, but is this balanced. Also, don’t misunderestimate the opportunity costs of trying to preserve our actual climate:

    I can just imagine it: scuba diving tours in 2100 to see the coral reef off Bognor – the Great Bognor Reef!

    If memory serves well, coral reefs disappeared for millions of years already. Yet they’re back. So they will if they ever disappear again. What’s a few dozens of dozens of dozens of dozens of dozens of dozens of years between friends of nature?

  198. Dave_Geologist says:

    Not in 2100 though. Maybe in 21,000. And of course the Great Barrier Reef has nowhere to go. Nothing to the south but ocean too deep for coral reefs to establish.

    I realise you’re being sarcastic Willard, but there are lots of people out there who fall for that schtick. Same with greening the Sahara or turning the permafrost into forest then farmland. Those things happen fast by geological standards (assuming it’s just ecotone and ecosystem migration that’s required, not recovery from extinction), but still slow by human standards: thousands of years. That’s a long time for seven million people to subsist on tinned beans.

  199. izen says:

    The common trope is that coral reefs are the ‘Tropical Rain Forests’ of the Oceans. Like a jungle they have the same complex ecologies, enable and support wide genetic diversity, and are exceptionally biologically productive.

    But as far as I can ascertain coral is not a major player in the base of any ocean food web. It does not grow enough to be a sustainable diet for anything but a small niche. The big sources are photosynth plankton in circum-polar waters. The result is krill in the S ocean and the shallow water diatom blooms and CO2 dipping during the Northern spring.

    To what extent does coral enable other prey and predator species to exist that do add significantly to ocean productivity ? How much of species diversity would be lost with the major coral reef building systems.?

  200. dhogaza says:

    izen,

    Try googling for “ecological services coral reefs”.

    Many pelagic fish species of economic importance are dependent on reefs for part of their lifecycle. NOAA states that about 25% percent of the species that are federally managed in the US fall into that category. In some countries, resident reef species are important sources of food.

    Perhaps JeffH will stop by and provide a lot more specifics.

  201. Green, Rebecca H., Ryan J. Lowe, Mark L. Buckley, Taryn Foster, and James P. Gilmour. “Physical Mechanisms Influencing Localized Patterns of Temperature Variability and Coral Bleaching within a System of Reef Atolls.” Coral Reefs, February 18, 2019. https://doi.org/10.1007/s00338-019-01771-2.

    This recent study shows that a strong mechanism for Temperature Variability / Coral Bleaching is that of long-period tides that impact the conventional SLH as well as cyclical shoaling of the thermocline, which on a larger scale forces the ENSO cycles.

  202. Dave_Geologist says:

    As dhogaza says, izen, it’s not just species that eat the corals that benefit (parrot-fish?). It’s the habitats they provide, for young fish of many pelagic species as well as for reef fish. By building a steep continental margin rather than a gentle muddy slope, they also focus nutrient-rich upwellling currents where they’re in the right place. And when the polyps die and decay they provide more nutrients, part of which is a new addition to the ecosystem, representing sunlight turned into sugars by their zooxanthellae. Similarly, mangrove swamps (another threatened nursery) and rain forests don’t just support the animals that eat the leaves of mangroves and forest giants.

    Big offshore reefs like the GBR are probably an irreplaceable post-glacial one-off, even at higher latitudes. To grow so tall they had to establish when sea level was 100-200m lower than today and grow upwards, keeping pace with sea level rise. To get comparable sea level rise today we’d need to melt Greenland and Antarctica. If we get to that point we’ll have too many other things to worry about to get excited by the novelty of a barrier reef where New York once stood. Even then we may not get new reefs – if SLR is too rapid, the corals won’t be able to keep pace and will die as they sink below the photic zone.

  203. ““How inappropriate to call this planet Earth when it is clearly Ocean.”
    — Arthur C. Clarke, Nature, 8 March 1990

    The issue as always is that attribution is difficult in climate science without having the ability to do controlled experiments. From the recent research articles, the focus has been on analyzing data from coral reefs that regulate temperature via tidal cycles versus wave action. I think this will be a focus of research in the future as it provides some discriminatory power.

  204. Dave_Geologist says:

    On it’s way to becoming Fire, Paul? There’s a TV series for that..

    It didn’t end well for either:

  205. I will pass on that, not much of a SciFi fan.. Pulled the Clarke quote from this paper from last year
    “The Ocean’s Role in Climate”, https://tos.org/oceanography/assets/docs/31-2_schmitt.pdf

    “Heat is absorbed by the ocean in lower latitudes and the eastern sections of ocean basins; heat is lost to the atmosphere at higher latitudes and on the western side of basins. The east-west asymmetry is due to the ocean’s anticyclonic wind-driven circulation: western boundary currents carry tropical heat to higher latitudes where it is transferred to the atmosphere. Of course, there is also mixing-driven overturning thermohaline circulation in the ocean, whereby energy from tides and wind cause downward mixing of heat and upwelling of cold water, as classically described by Munk (1966) and Munk and Wunsch (1998). With tides driving the mixing in the presence of the imposed meridional temperature gradients, the thermohaline circulation would carry heat poleward even if the winds ceased to blow. “

    Compared to the tributes to Broeker, less was said about Munk, who died the week before Broeker. Much more impressive research as his ideas on tides are starting to shoal.

  206. Chubbs says:

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