A “hiatus” in some people’s “skepticism”?

There’s a new paper doing the rounds of the blogosphere, called Varying planetary heat sink led to global-warming slowdown and acceleration. Judith Curry has a post about it. The basic result of the paper is that the “missing heat” is going into the deep parts of the Atlantic because a salinity variation is allowing warm water to sink rapidly. That sounds plausible, but I don’t really know enough to judge. The reason it’s generated some interest seems to be because it suggests that the “hiatus” will last another decade or so, and because it suggests (although this appears to only be in the press release) that only half the warming between 1970-2000 was anthropogenic (or due to global warming).

The paper concludes with

The next El Niño, when it occurs in a year or so, may temporarily interrupt the hiatus, but, because the planetary heat sinks in the Atlantic and the Southern Oceans remain intact, the hiatus should continue on a decadal time scale. When the internal variability that is responsible for the current hiatus switches sign, as it inevitably will, another episode of accelerated global warming should ensue.

Many seem to ignore the very end of that sentence and focus only on the part that says the hiatus should continue on a decadal time scale. Now, the paper seems to have gone through the historical records (including the Central England record) and found some kind of 60-70 year pattern of warm and cool phases, and is then arguing that we’re in some kind of cool phase now and that it will last another decade or so, since it has existed for about 15 years already.

One issue I have is that it is very likely that none of the cool phases in the past were coincident with the planet being significantly out of energy balance – as we are now. Even though we are in this supposed cool phase, we are still warming at something like 0.1 degrees per decade (which is something else the paper rather failed to point out). It’s possible that we could sustain this slowdown for another decade or so, but if we continue increasing our emissions, that would imply that we could remain in a cool phase with slow surface warming even when the energy imbalance is > 1 Wm-2. I find that somewhat implausible, but I may well turn out to be wrong.

Although I find the possibility that the “hiatus” could continue for more than another decade, or longer, a little unlikely, there is a claim in the press release that I find rather strange. It says

Rapid warming in the last two and a half decades of the 20th century, they proposed in an earlier study, was roughly half due to global warming and half to the natural Atlantic Ocean cycle that kept more heat near the surface.

When people say things like this, it makes me think that they don’t really understand anthropogenic global warming (AGW). AGW is simply the fact that we are increasing atmospheric greenhouse gas concentrations (GHGs) which then act to trap outgoing radiation, producing an energy imbalance, and increasing the energy in the climate system. There isn’t really some special anthropogenic mechanism that simply heats the surface. The surface warms because some of this extra energy heats the surface, increasing the surface temperature, which then reduces the energy imbalance.

On the other hand, its very likely that variability means that sometimes the surface will warm faster than at other times. Therefore one could define the anthropogenic (global warming) contribution as the mean long-term trend, and the natural contribution as being variations from this mean. If we consider the period 1970-2000, the Skeptical Science Trend Calculator suggests that we were warming at 0.16 degrees per decade. If half of this is global warming and half is natural, that would suggest that the global warming contribution was 0.08 degrees per decade. If so, that would suggest that over about a 60 year period, the trend should be 0.08 degrees per decade. However, this would imply that the trend since 2000 would have to be about 0 degrees per decade, which it isn’t. In fact, if you go back to the Skeptical Science Trend Calculator, the trend from 1970-2014 is also about 0.16 degrees per decade. So, if half the warming between 1970 and 2000 was natural, and we’ve been in a cooling phase since 2000, how can the 1970-2014 trend be the same as the 1970-2000 trend. It doesn’t really make sense.

So, as far as I can tell, the press release has a claim that isn’t in the paper and that doesn’t really make much sense, and the conclusion about the hiatus continuing for another decade or so is really just based on identifying some kind of 60-70 year cycle in the historical records – none of which contain periods really comparable to what we’re going through today. If I remember correctly, there was a massive outcry when the press release for the Marcott et al. Holocene temperature reconstruction paper rather overplayed the significance of part of their reconstruction. I wonder if the same people will be similarly shocked by the, apparently, unsupported claims in this press release? Don’t bother answering that question. I suspect we all know the answer. And, to be honest, I don’t really care. I do wish people wouldn’t overplay the significance of their papers in press releases, but they do and it’s really a systemic problem, rather than just a few individuals.

Posted in Climate change, Climate sensitivity, ENSO, Global warming, Judith Curry, Science | Tagged , , , | 25 Comments

Salby again!

After my last encounter on Bishop-Hill, I had a thought that I might simply avoid commenting there. However, when someone suggested that Rupert Darwall was a perceptive chap, I couldn’t resist pointing out that this was only true if regarding complete nonsense as having merit, qualified as perceptive. For context, Rupert Darwall recently wrote an article defending the – unpublished – work of Murry Salby, who happens to think that the rise in atmospheric CO2 is natural, and not anthropogenic. Well, he is very obviously wrong. My comment, however, lead to a new Discussion thread where I was challenged to show why Darwall and Salby are wrong. I tried, but I don’t think I managed to convince anyone there.

The problem I have is that showing that Murry Salby’s ideas are wrong is extremely easy. Consider the figure below. It shows how much CO2 we emit through burning fossil fuels, how much is absorbed and emitted by the oceans, and how much is absorbed and emitted by the biosphere (of which we’re also part). What’s fairly clear is that both the oceans and the biosphere absorb more than they emit (we don’t really absorb any as we’re not currently creating fossils, or – at least – not nearly fast enough). If the oceans and biosphere are absorbing more than they emit, then they very clearly cannot be the source of the increase in atmospheric CO2 and – in fact – are absorbing almost half of what we emit. The rise in atmospheric CO2 is, therefore, all us. To illustrate how well Bishop-Hill gets this trivial concept, there is a Bishop-Hill post that attempts to mock Bob Bindschadler by pointing out that the oceans and biosphere emit much more than we do, while failing to point out that they then absorb more than they emit.

Source : Fig 7.3, IPCC AR4

Source : Fig 7.3, IPCC AR4


You can even do more. The isotope ratios (C14, C13, and C12) tell us that the source must be old biological organisms (fossils). The reduction in atmospheric oxygen tells us the source is something being burned. There are multiple lines of evidence that show that Murry Salby’s suggestion that the rise in atmospheric CO2 is natural, is complete and utter nonsense.

So, here’s the conundrum I have. Bishop-Hill is just a blog and it’s also a free world. People can say whatever they like and if they want to promote silly ideas, that’s fine. Under normal circumstances I would simply ignore it – there are plenty of blogs spouting nonsense about climate science that I happily ignore. However, this is not just any old blog, it is run by someone (Andrew Montford) who has quite a high-profile, in the UK at least. He appears on the radio, on television, writes articles for magazine, and is quoted in newspaper articles. Yet, he appears not to understand, or accept, what is a trivial – but crucial – aspect of this topic. If he were honest, the next time he’s asked to talk about this topic in the media, he might respond with : “Sorry, maybe you should find someone else. I don’t understand this very well.” Maybe, also, the next time he writes a post mocking Julia Slingo – the Met Office’s Chief Scientist – he should consider the possibility that the reason he doesn’t get mocked more often is that decent people don’t mock those who have trouble understanding really simple concepts. I really do think we need a better class of climate “skeptic”.

Posted in Climate change, ClimateBall, Global warming, IPCC, Science | Tagged , , , , , | 69 Comments

Understanding the “pause”

I thought I might briefly highlight a recent paper that tries to understand what some call “the pause”, but which isn’t really a “pause” as nothing has actually stopped. The paper is Natural variability, radiative forcing and climate response in the recent hiatus reconciled, by Marcus Huber and Reto Knutti.

What they’ve done is to run an unforced control run of a CMIP5 climate model, from which they extract a segment that matches the observed NINO3.4 index for the time period of interest. They then run a suite of forced climate models, but with updated stratospheric aerosol and solar forcings, and then adjust these using the portion of the unforced model which matches the NINO3.4 index, resulting in the ENSO effect producing a cooling of 0.06oC and the adjustments to the forcings producing a cooling of 0.07oC. The paper then compares the model results with the HadCRUT4 temperature dataset and with the Cowtan & Way (2013) correction to the HadCRUT4 dataset (which includes satellite data for the Arctic to compensate for coverage bias). The basic result is shown in the figure below, and illustrates that with all the corrections, the best fit is to a model with a Transient Climate Response (TCR) of 1.8oC, and an Equilibrium Climate Sensitivity (ECS) of 3oC.

Comparison of model runs and temperature datasets from Huber & Knutti (2014).

Comparison of model runs and temperature datasets from Huber & Knutti (2014).


So, basically, this result suggests that despite a “pause”/hiatus/slowdown in surface warming we will still likely have warmed by 1.8oC (relative to pre-industrial times) when we’ve doubled CO2 and – if CO2 concentrations remain at that level – we’ll eventually warm by 3oC. Not really all that surprising really.

What can often happen when such papers are published is that some criticise scientists for focusing so much on anthropogenic effects, and ignoring other non-anthropogenic effects. Well, in a sense this paper didn’t. It ran a suite of unforced models to try and extract a segment with NINO3.4 indices similar to the period of interest. Unforced means that there are no external forcings, so the only factors included were internal variability. Did these runs show long-term warming? No, because if there is no change in external forcing, then the equilibrium temperature is essentially fixed. Internal variability can cause temperatures to rise above, and fall below, equilibrium, but it can’t cause long-term warming because temperatures will quickly return to equilibrium. If internal variability could produce a change in forcing, then it could cause long-term warming, but we’re unaware of any internal process that can actually do this.

The paper also considered updates to stratospheric aerosol (volcanoes) and solar forcing, so it did consider other natural effects. Essentially, all of the work that tries to understand the “hiatus” is leading to the same basic conclusion : it is simply a consequence of internal variability that can lead to periods when we warm faster than average, and others when we warm slower, but doesn’t really change what we should expect to happen in the medium- to long-term as a consequence of anthropogenic emissions. Maybe those who keep arguing that there is some kind of natural effect that could both explain this and result in significantly lower climate sensitivities, could actually explain what this natural effect is. Simply proposing something without actually explaining what it is or how it works, is just a little silly. It’s possible that those who seem to think that they might be consensus busting geniuses should really start considering that they’re not.

Posted in Climate change, Climate sensitivity, ENSO, Global warming, Science | Tagged , , , , , , , , , | 78 Comments

Woo hoo, fame at last!

It appears that I now have my very own Josh cartoon, currently being promoted on Bishop-Hill and Watts Up With That. I think I made an appearance in an earlier one, but this is the first to focus only on me (I think William Connolley has a pithy comment about things being about him, but I can’t quite remember it). It’s this kind of gentle joshing (see what I did there) that makes me feel as though I’ve finally been accepted as part of the climate science blogging community. I get the feeling that the intention of the cartoon was to be explicitly insulting, but I guess I can interpret it any way I like. Also, I did find it a little amusing. If you can’t at least have a laugh now and again, there’s not really much point in being involved in these kind of things. The only thing that confuses me is how Josh knew what I looked like.

Maybe the most ironic aspect of this is that I think it relates to a discussion between Andrew Montford and myself in which Andrew had rather a large sense of humour failure when I was a little more robust (honest?) than maybe I should have been. By should have been I mean if I wanted to avoid annoying Andrew, that is. Even discussion is not quite the right word as it mainly involved Andrew being defensive and then getting cross. I guess if you don’t really know what you’re talking about, but don’t want to admit it, then that might be the only way to engage in such exchanges (ooops, is that a little too robust again, sorry).

Anyway, I guess the only thing I need to decide now is whether or not to print this out and put it on my office door.

Credit : Cartoons by Josh

Credit : Cartoons by Josh

Posted in Climate change, ClimateBall, Comedy, Personal, Satire, Science | Tagged , , , , , , , | 92 Comments

The impact of climate change

As a physicist I think I understand the impact of climate change from a physics perspective. If we continue adding CO2 to the atmosphere, we will continue – on average to warm. We also have projections for the range of warming based on different possible future emissions pathways. We also expect polar amplification; the Arctic will warm faster than regions at lower latitude. This will change the latitudinal temperature gradient and should affect global weather patterns. We expect the hydrological cycle to intensify; regions that already have lots of rain will probably get more, and regions that are dry, will get drier. This will likely influence flooding and droughts.

Adding energy to our climate system is also expected to increase the intensity and frequency of some extreme weather events. These are complex processes, so we may not be able to predict accurately what will happen, but we already have some evidence to suggest a relationship between the intensity of Tropical Cyclones, and sea surface temperature.

However, what I don’t know much about is how – more specifically – these changes will influence us. How will a warmer world influence our (humans) ability continue living in a manner similar to, or better than, we are today? So, a few days ago, I was emailed an infographic that tries to explain what might happen. The source is here, but I thought I would also post it below. I don’t know the credibility of the information on the graphic, but I thought some of my more well-informed commenters might know more about this than me, and may be able to clarify whether or not what this infographic presents is a reasonable representation of our current understanding of the possible impacts.

Source : Inforgraphicworld

Source : Inforgraphicworld

Posted in Climate change, Global warming, Science | Tagged , , , , , | 99 Comments

A new tagline?

I’m starting to think that it may be time for a new tagline. It’s not that I don’t intend to continue trying to keep things civil, it’s more that my tagline seems to be more a rod for my back, than anything else. I haven’t always succeeded in my goal of trying to be civil, but I can only think of 4 or 5 occasions when I’ve been rather less civil than I might hope to be. That doesn’t seem too bad in more than a year of discussing what is clearly a contentious topic. Also, one involved Stephen Goddard, so I’m not sure that really counts. Of course, if I do behave less civilly than I should, the normal retort is then “what happened to your civility”? It seems some don’t understand the meaning of the word trying and also that my stated aim of trying to be civil doesn’t then give them free reign to act like jerks without being called out.

Strangely, though, Andrew Montford appears to be claiming that I was rude about him when he blocked me. I neither remember being rude about him, nor him blocking me, so I’m rather confused by this claim. Maybe Andrew thinks that two wrongs makes a right. If I was to follow the normal procedure in these circumstances, I would strongly state that what he’s said is libelous, and that he should retract what he’s said or provide proof, but that’s just too childish for words in these circumstances. I’ve no idea why he’s chosen to say something that appears not to be true, but presumably he has his reasons. I have no great interest in finding out.

I don’t quite know whether or not I should change my tagline and, if so, what I should change it to. I quite like this one, but I think that there are many involved in this topic who don’t get irony. So, I thought I might ask my well-informed readers if they had any suggestions. If you do have a view, feel free to make it through the comments.

Posted in Personal, Satire | Tagged , , , | 78 Comments

A challenge?

A comment by William Connolley on Sou’s recent post lead me to Joanne Nova’ site. The post on Joanne’s site, that William had highlighted, was about how the media distorts the news and contained the classic line

If the world does indeed move into a cooling period, its citizens are ill-prepared.

Yes, let’s prepare for all eventualities, apart from the one that evidence suggests is most likely to actually happen! This seems to be the anything but warming variant of the anything but CO2 theme.

In paging down Joanne’s site I came across a post about it being an unsettling climate for skeptical scientists, in which she discusses an article by Rupert Darwall. The article, which I can’t actually access, appears to be a defence of Murry Salby. Yes, Murry Salby. Was this from ages ago, before everyone knew that Salby’s ideas were complete nonsense? No, it’s from this month. As I said, I haven’t read the article as I can’t seem to access it, but Joanne appears to quote from it

In Salby’s view, the evidence actually suggests that the causality underlying AGW should be reversed. Rather than increased levels of CO2 in the atmosphere triggering global temperatures to rise, rising global temperatures come first—and account for the great majority of changes in net emissions of CO2, with changes in soil-moisture conditions explaining most of the rest.

Yes, that may be Salby’s view but he’s wrong. It then includes

Why is the IPCC so certain that the 5 percent human contribution is responsible for annual increases in carbon dioxide levels?

Because it is!

As a result of this, I ended up in a Twitter debate about this today with Rupert Darwall, in which I may have called him a prat. Okay, I did call him a prat; well, that he was acting like one, at least. What struck me, however, is that if you look at his Twitter followers, it contains a reasonable number of climate scientists, including some who appear to think that it’s important to call out over-confidence from other scientists, and alarmism in the media. If they’re doing this, why aren’t they calling out Darwall’s very obvious garbage.

So, I had considered challenging people who think it’s important to call out over-confidence and alarmism, to also call out demonstrable nonsense. However, sticking with a theme, I think that’s a little prattish. I don’t think that scientists who engage publicly should really be obliged to do anything in particular. If they want to just talk about their own science, fine. If they want to call out over-confidence and alarmism, fine. If they want to call out scientific garbage, fine. It’s really up to them.

What I will say, though, is that if their goal is to help the public get the clearest possible understanding of climate science, but they find that they call out over-confidence and alarmism far more often than they call out nonsense, maybe they’re not doing the best job that they could. They may also not be being entirely consistent. Similarly, if they’re calling out over-confidence and alarmism because a minority tells them that that is what is required in order for scientists to be trusted, then they may be doing it for the wrong reason. Also, if they think that doing so will suddenly increase some people’s trust in climate scientists, then possibly they should take someone else with them when they buy a secondhand car.

Personally, I wish more climate scientists would be more vocal when others present complete and utter garbage. However, that’s just what I would hope for and climate scientists have a hard enough time without me criticising them further. In truth, it’s likely that there’s not much that they could do to really improve the quality of some of what is presented, by the media, to the public.

Also, although I do think that over-confidence and alarmism can be damaging, the situation isn’t symmetric, and deciding what is obviously alarmist isn’t necessarily simple. Different people may have different views about the evidence and also about how best to present it to the public. On that note, I came across an excellent interview with Robert Bindschadler. It contained the following comment

The other thing that led me into a retreat is you would go out there and try to limit your emphasis on caveats and speak more crisply or without the caveats and with more black and white and you would be shot in the back by your colleagues. …… But you have to consider the audience. If all you do is lace it with uncertainty, it gives them reason to do nothing.

So, although calling out over-confidence and alarmism is important, I do think that those doing so have to be careful that rather than being objective, they’re imposing their own view of how best to present the information, and possibly failing to account for their own biases. Anyway, this quick post has ended up rather long, so I’ll leave it there. Anyone with other views or thoughts, is welcome to present them through the comments.

Posted in Climate change, Global warming, Satire, Science | Tagged , , , , , , , | 72 Comments