There have been a couple of recent papers presenting analyses that claim to have narrowed the likely range for equilibrium climate sensitivity (ECS). One is Dessler et al. (currently a discussion paper under review) which suggests that the 500hPa tropical temperature better describes the planet’s energy balance and infers an ECS of 2.1K to 3.9K. The other is Cox et al. who use variability of temperature about long-term historical warming to constrain the ECS to 2.2K to 3.4K. Both suggest a narrower range than that suggested by the most recent IPCC report (1.5K to 4.5K).
James Annan has a post which suggests that these new papers are interesting but that there may be unaccounted for uncertainties. I largely agree and won’t say any more myself. I was, however, going to mention a few aspects of this that I think are relevant.
I thought how this was framed in the media was somewhat unfortunate. For example, Yes, global warming will be bad. But these scientists say it won’t reach the worst-case scenario. It does indeed seem that these studies are suggesting that the worst case scenarios might be less likely than we had previously thought. However, the public debate seems to be dominated by those who think everything will be fine (Lukewarmers) and those who are mostly in the middle of the mainstream. In fact, there is often quite a lot of pushback against any who present worst case scenarios.
The significance of these new studies to the public climate debate therefore seems to be that they largely rule out the Lukewarmer position. Yet, this is not really how they’ve been presented. One prominent Lukewarmer has even claimed that these studies are a vindication for Lukewarmers. Presenting these studies as having ruled out the worst case scenarios, rather than the best case scenarios, probably hasn’t shifted the public climate debate very much.
Another issue is that there is often an apparent confusion between climate sensitivity and how much we will warm. Yes, climate sensitivity is relevant, but so is how much we emit. These new studies have potentially narrowed the range, but they don’t really change the best estimate (about 3K). The more extreme scenarios (both low and high) may be less likely, but we can still potentially emit enough to warm substantially. In a sense, how much we will probably warm is largely unchanged.
Additionally, a common way to quantify how we could achieve some temperature target is to present a carbon budget; the amount of CO2 we can emit if we want some chance of staying below the target. Given that these new analsyses don’t really change the ECS best estimate, the carbon budget that would give us a 50:50 chance of staying below some target should be unchanged. Often, however, the carbon budget is presented as giving us a 66% chance of staying below some temperature target.
Given that the range might now be narrower, this might suggest that the carbon budget for a 66% chance might be slightly bigger. However, it’s not only the uncertainty in climate sensivity that constrains this; there are also carbon cycle uncertainties (i.e., what fraction of our emissions will be taken up by the natural sinks). Hence, I suspect that the impact on the carbon budget framework might be small (I might be wrong about this).
Also, although I’m mostly in favour of working within a carbon budget framework (it’s a pretty straightforward metric) I do sometimes think that there might be a better way to present it (to be fair, I don’t have any good suggestions as to what this should be). A carbon budget that gives us a 66% chance of staying below some temperature target doesn’t mean that we will do so 2/3 of the time, and fail 1/3 of the time. There is only one outcome; we will either stay below the temperature target, or we will not.
If we think that there is now a bigger chance of staying below some temperature target, it’s not clear to me that we should then adjust the carbon budget. Maybe it would be better to present it as there now being a bigger chance of succeeding, than suggesting that we can now emit more while still having the same chance.
Okay, I think that’s long enough, so I’ll stop there. The latter part of this post is not as clear as I would have liked, so if anyone has other suggestions as to what we should do given these new results, feel free to make them in the comments.
Update:
Andrew Dessler’s comment is worth reading. I had forgotten that their paper was more presenting what might be a better way to constrain the energy balance, rather presenting a firm estimate for an ECS range.
...and Then There's Physics 
The chance of a 2°C warming likely did not change much with this paper. That is nicely in the middle and the mean estimate of the climate sensitivity did not change. But the chance of a ten degree warming would decrease a lot if this paper turns out to be solid.
That is a big deal. Looking at the probability distributions below you can see that the lower limit is already quite well known, but getting a handle on the upper limit of the climate sensitivity is hard. If this paper did so, that would be a big deal.
https://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch9s9-6-2.html
Let the luckwarmer sprout their nonsense about this paper, otherwise they would embarrass themselves about something else. That is not something that should influence what reasonable people do or say.
They also revealed how duplicitous the fans of the uncertainty monster are. The mean sensitivity hardly changed with this paper, the main thing is a reduction in the uncertainty (if it holds). If they cheer this paper they admitted that the uncertainty monster is not humanity’s friend, but that actually uncertainty is a reason for faster stronger action to fight climate change.
http://variable-variability.blogspot.com/2015/12/judith-curry-uncertainty-monster-high-risk.html
Victor,
Absolutely. It would be great if we can really out rule such large warming.
Indeed, but it would be nice if those in the media were careful to frame things in ways that didn’t play into their hands.
Good point. I hadn’t thought of that.
The main point of our paper is a critique of energy balance estimates of ECS based on the 20th century historical record. We think that low estimates of ECS from the 20th century historical record (i.e., Otto et al., Lewis and Curry) are not guaranteed to get the right answer, even if we knew the input variables (i.e., forcing) perfectly.
By itself, our paper does not tell us the low value are wrong — but it gives a mechanism that demonstrates they COULD be wrong. However, Kate Marvel and Kyle Armour both have analyses they talked about at AGU that shows that, indeed, the surface pattern of warming we’ve experienced over the past few decades will imply a much lower ECS than reality. My guess is that, in a year or so, no one will take those low energy-balance estimates seriously and everyone will agree ECS > 2 K.
The ECS estimate in our paper is just an example of what you can do with our framework, not something I’d every cite as a firm estimate. In fact, it’s an emergent constraint estimate, which, if you read my twitter feed, you’d know I’m not crazy about. To understand why it’s in there, you have to know something about the history of the paper. We had previously submitted a version that does not have the ECS estimate in it to another journal. The reviewers seemed confused about the utility of our revised energy balance framework and questioned what the point was. In response, we decided we had to better show what the potential uses were, so we put that short discussion of ECS in the paper. However, you’ll notice that we don’t site as numbers in the abstract or the conclusions — that’s a signal that the values are for illustration and not to be considered a firm value. We have another paper that is basically ready to submit that has a more rigorous ECS range (likely 2.4-4.5 K) based on our revised energy balance framework.
Andrew,
Thanks. Now that you’ve commented, I remember that when I read your paper I did take this from it, but had forgotten by the time I wrote the post.
Interesting. This seems consistent with other things I’ve seen that are strongly indicating that an ECS below about 2K is unlikely.
There are many other estimates of ECS, and these sound unlikely to affect the carbon budget much, even if they narrow the fat tail. Would you agree with a comment I’ve seen that these do not include earth system feedbacks?
Another supposed narrowing, but more towards top of IPCC range is Brown & Caldeira, 2017: https://www.carbonbrief.org/new-study-reduces-uncertainty-climate-sensitivity
who’s the lukewarmer who says these papers are vindication for their position?
Andrew,
That was Matt Ridley.
The lukewarmer (luckwarmer as some have it) claiming vindication is Matt Ridley. https://twitter.com/mattwridley/status/954301752379047937
I don’t know where Matt Ridley gets “That’s far below what the UN has said for decades from”. Presumably he’s confusing how much we will actually warm (which depends on how much we emit) and how how much we will warm if we double atmospheric CO2. We can emit enough to more than double atmospheric CO2.
Here’s a figure that relates cumulative emissions, temperature change and also shows (in the bubbles on the graph) the corresponding atmospheric CO2 concentration. ECS does not tell us how much we will warm, it is simply a metric that indicates how much we will eventually warm after doubling atmospheric CO2. Since we could emit enough to more than double atmospheric CO2, we can clearly warm more than the ECS.
Something about Matt Ridley and rearranging the deck chairs on the Titanic comes to mind.
From the Cox 2017 abstract …
“Here we present a new emergent constraint on ECS that yields a central estimate of 2.8 degrees Celsius with 66 per cent confidence limits (equivalent to the IPCC ‘likely’ range) of 2.2–3.4 degrees Celsius.”
So 17% chance below 2,2C and 17% chance above 3.4C.
Denier headlines …
17% chance ECS below 2.2C
50% chance ECS below 2.8C
83% chance ECS below 3.4C
“This metric of variability can also be calculated from observational records of global warming3, which enables tighter constraints to be placed on ECS, reducing the probability of ECS being less than 1.5 degrees Celsius to less than 3 per cent, and the probability of ECS exceeding 4.5 degrees Celsius to less than 1 per cent.”
Denier headline …
ECS three times more likely to be below 1.5C than above 4.5C!
There is a disconnect between how this is understood by those interested in the subject, and those that just pick up the media constructed zeitgeist.
I recently met an old friend, who knowing my interest in the issue, told me how he had recently read somewhere (Murdoch press?) that ‘scientists had discovered that Global Warming would not be as bad as previously predicted’.
Explaining that a small reduction in the ‘worst case’ scenario does not change the ‘most likely’ outcome is probably ineffective in countering the intentional shift in public perception that such reporting generates.
I can never work out if Ridley deliberately distorts the facts or if he just doesn’t know or care how wrong he is. Either way, it’s embarrassing.
@-BBD
“Either way, it’s embarrassing.”
It is a skill (feature not a flaw?) imported from his banking experience.
“I am delighted to announce that 2006 has been another excellent
year for Northern Rock. Our strategy of using growth, cost
efficiency and credit quality to reward both shareholders and
customers continues to run well.
We reached all of our strategic goals and grew both assets and
profits to record levels. We increased lending by 23% taking us
to the position of fifth largest UK mortgage lender by stock.
Our assets increased by almost 24% to pass £100 billion
and we recorded underlying profit growth of over 19% – well
within our newly upgraded strategic range.”
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I strongly doubt there are more than a couple of thousand people in the UK who would know enough of this paper to rate it more newsworthy than the Alexis Sanchez transfer saga.On the plus side that means Riddley as well until he whips up a new article behind The Times paywall about how right he was all along.
It will make an impact on people who have roles in planning or policy. Not as the paper itself but as the advice that gets filtered down to them.
Most people accept the need to act on climate change but this does not driven them in the polls, that is still a mixture of social and economic concerns. My gears are running and I am thinking out loud but perhaps the best use of this is a list of sensitivity papers to counter the “most recent papers show low sensitivity” meme that has floated around for a couple of years? Instead of one news story have a go to source that shows that most studies including most recent ones favour something close to the IPCC range or higher.
“who’s the lukewarmer who says these papers are vindication for their position?”
someone who is not a lukewarmer.
I will say one thing. It would do the community some good to Ditch RCP 8.5. It cant happen.
RCP 8.5 is no more credible than an ECS of less than 1.5C.
Steven,
I think there are two main reasons for retaining RCP8.5. One is mainly scientific. It’s easier to extract a signal from the noise, when the signal is large relative to the noise. Using a forcing pathway like RCP8.5 allows us to better understand (I think) how anthropogenically induced changes could influence our climate. Yes, the changes may be larger than we expect, but it still gives us a sense of which changes will be anthropogenic versus what could simply be internal variability.
The other is actually that I don’t think we can actually rule it out. Uncertainties in the carbon cycle (and the possibility of carbon cycle feedbacks) means that we could follow and RCP8.5 concentration pathway even if follow an emission pathway normally associated with a smaller change in anthropogenic forcing.
someone who is not a lukewarmer..
Ridley self-identifies as a lukewarmer. So do many who would likely support the rhetoric in his column, IMO.
Seems to me that there are no objective definitions of these terms, and pretending otherwise (arguing by assertion) isn’t in any way productive. Trying to throw Ridley under the lukewarmer bus by declaring that his views are inconsistent with lukewarmism doesn’t make Ridley not a lukewarmer. In the context of the public discussion, he’s a lukewarmer. Maybe better is to simply describe, for the self-identified lukewarmer’s you might influence, why you think his arguments are flawed.
Steven,
I will say one thing. It would do the community some good to Ditch RCP 8.5. It cant happen.
Why?
I think this is SM’s:
1. barely measurable? mousewarmers
2. 1-3C per doubling? lukewarmers
3. 3-6C per doubling? alarmists
4. 6C+ catatrophists.
I assume the above is ECS?
Mooney at WaPo also said scientists can rule out some of the most dire scenarios…
How much?
Take the 4.5 C of the IPCC’s ECS. Reduce that to 3.4 C. 4.5 can be suggested to be a punishing number with higher ones worse exponentially. The lower numbers around 1.5 C are soft and fuzzy like a furry animal you buy for a child. So the numbers that weigh the most are the bigger ones. Going along with the story of Lukewarmers, it helps. Using a bell curve distribution which is not correct (see the AR4 distribution above) but easier to figure, we had 1/6 of it above 4.5 C and we now have 1/6 of it above 3.4 C. 3.5 to 4.5 C of the range dropped below the higher 1 sigma level. The dangerous upper tail lost a lot of area. As the distribution narrows and becomes more useful, the danger reduced on the high end. I’d argue there isn’t much on the low end especially for the United States.
RCP8.5 is more likely than RCP2.6
Steven,
I will say one thing. It would do the community some good to Ditch RCP 8.5. It cant happen.
Why?
because it can’t happen and people misuse the results from it, calling it BAU when it most definately not BAU. And because wall time is fucking precious. If wall time were free we could run every option from 1 to 10 at .1 Watt increments,
but wall time is not free.
‘RCP8.5 is more likely than RCP2.6’
Kill that one too then
“1. barely measurable? mousewarmers
2. 1-3C per doubling? lukewarmers
3. 3-6C per doubling? alarmists
4. 6C+ catatrophists.’
nope. 0 to 1.5C: Lunatics.
1.5 to 4.5: Not insane
4.5+ : Alarmists
Steven,
Again, I’m not convinced that an RCP8.5 concentration is as unlikely as you seem to be suggesting.
Yes, but such people seem to be rare. Yet, “alarmist” seems to be a phrase that is used quite often and often to refer to those that you describe as “not insane”.
RCP 8.5 ( like A1F1 sres before it )
This future is consistent with:
Three times today’s CO2 emissions by 2100
Rapid increase in methane emissions
Increased use of croplands and grassland which is driven by an increase in population
A world population of 12 billion by 2100
Lower rate of technology development
Heavy reliance on fossil fuels
High energy intensity
No implementation of climate policies
Not gunna happen.
From a purely scientific standpoint, if wall time is free, then Sure run it. run it, run 8.15, run
7.85… blah blah blah
but I would not waste GCM time on it.
Even worst they plan to run it out to 2300.
Steven,
because it can’t happen
Really going to need something better than that as an argument.
calling it BAU when it most definately not BAU.
It definitely is BAU. The definition is that it involves no or minimal specific mitigation policy. Also now often called ‘baseline’. As shown here, it’s within the 80% interval for baseline-designated scenarios at end of century and is the only scenario within that interval.
Since they have included an RCP 7.0 for Ar6, I think that should tell you every disaster story we can hope to avoid.
RCP 8.5 is possible – if we see those political forces that are unreasonably pro-coal in power oveer large areas. And by ‘unreasonably pro-coal’ I would mean those who are essentially prepared to subsidize coal directly whilst putting obstacles in the way of renewables, nuclear et. al. Such a path would also involve the large scale use of tar sands and Orinoco heavy oil, perhaps with CTL for transport.
Is that unreasonable? Right now, yes, but politics can change, and there are those out there lobbying for more coal use.
Steven,
As far as the term BAU goes, I interpret it as a “do no mitigating” pathway, not as a “what we will actually follow pathway”. In a sense, we don’t want to follow a BAU pathway.
‘Yes, but such people seem to be rare. Yet, “alarmist” seems to be a phrase that is used quite often and often to refer to those that you describe as “not insane”.
Yes, I see very little alarmism.
but if you asked me what I would call alarmist 4.5= would be it.
The people who use the ‘alarmist language” to describe the not insane, are the lunatics.
‘Is that unreasonable? Right now, yes, but politics can change, and there are those out there lobbying for more coal use.”
yes there are boogey men. and monkeys could fly out of my butt.
RCP 8.5 ( like A1F1 sres before it )
A1F1 was actually very different from that particular RCP8.5-type scenario:
‘A future world of very rapid economic growth, low population growth and rapid introduction of new and more efficient technology. Major underlying themes are economic and cultural convergence and capacity building, with a substantial reduction in regional differences in per capita income. In this world, people pursue personal wealth rather than environmental quality.’
There are many ways to get to 8.5. If there’s a defining feature it’s probably very high energy demand.
“Steven,
As far as the term BAU goes, I interpret it as a “do no mitigating” pathway,”
We are already mitigating
We are already moving away from FF.
if we continue this business as usual we will definiately not have RCP 8.5
To get 8.5 we have to hit the worst case population estimates
We have to reverse mitigation, and go whole hog for FF which is being defeated in the market
We basically have to go insane.
So ya, for scientific purposes we can study what happens if monkeys fly out of my butt and if the whole world goes more insane than trump.
And we can do RCP 7.0, in which 75% of the world goes bonkers.
sorry paul
My mistake. Some people compare it to A2 scenarios and Some to A1s
Click to access A-guide-to-RCPs.pdf
“Kill that one too then”
As I understand it, the scenarios are more dictated by the requirements of politicians than to reflect scientific or socio-economic realities. They are there to inform policy, not science. When politicians want diffierent scenarios, then we have a reason to change them.
And for forcing it is A1f1
if you believe whats posted at skepticalscience.
here
Click to access RCP_Guide.pdf
See page 19..
coal use.
ya
monkeys
butt
exit
Steven,
What I’m suggesting is that the definition of BAU doesn’t necessarily change. That we are actually doing something doesn’t change that RCP8.5 is what we probably have followed if we had done, and continued to do, nothing. I can see, therefore, why some might still want to refer to RCP8.5 as BAU.
My own view is that we have to be slightly careful of conflating emission pathways and concentration pathways. There isn’t a one-to-one relationship between the two. As far as I’m aware, a concentration pathway close to RCP8.5 is still possible even if we follow an emission pathway typically associated with a lower concentration pathway. I’m not convinced, therefore, that RCP8.5 is no longer possible as a concentration pathway.
Steven.
Coal use. Value and scarcity of liquid fuels. RCPs on steroids. Your butt.
DK?
Hmm
Click to access gmd-9-1937-2016.pdf
In preparing for CMIP6, the CMIP Panel (the authors of this
paper), which traditionally has the responsibility for direct
coordination and oversight of CMIP, initiated a 2-year process
of community consultation. This consultation involved
the modelling centres whose contributions form the substance
of CMIP as well as communities that rely on CMIP
model output for their work. Special meetings were organized
to reflect on the successes of CMIP5 as well as the scientific
gaps that remain or have since emerged. The consultation
also sought input through a community survey, the scientific
results of which are described by Stouffer et al. (2015).
Four main issues related to the overall structure of CMIP
were identified.
First, we identified a growing appreciation of the scientific
potential to use results across different CMIP phases. Such
approaches, however, require an appropriate experimental
design to facilitate the identification of an ensemble of models
with particular properties drawn from different phases of
CMIP (e.g. Rauser et al., 2014). At the same time, it was
recognized that an increasing number of Model Intercomparison
Projects (MIPs) were being organized independent of
CMIP, the data structure and output requirements were often
inconsistent, and the relationship between the models used in
the various MIPs was often difficult to determine, in which
context measures to help establish continuity across MIPs or
phases of CMIP would also be welcome.
Second, the scope of CMIP was taxing the resources of
modelling centres making it impossible for many to consider
contributing to all the proposed experiments. By providing a
better basis to help modelling centres decide exactly which
subset of experiments to perform, it was thought that it might
be possible to minimize fragmented participation in CMIP6.
A more federated experimental protocol could also encourage
modelling centres to develop intercomparison studies
based on their own strategic goals.
Third, some centres expressed the view that the punctuated
structure of CMIP had begun to distort the model development
process. Defining a protocol that allowed modelling
centres to decouple their model development from the CMIP
schedule would offer additional flexibility, and perhaps encourage
modelling centres to finalize their models and submit
some of their results sooner on their own schedule..
…..
These proposals were broadly reviewed within WCRP with
the goal to encourage and enhance synergies among the different
MIPs, to avoid overlapping experiments, to fill gaps,
and to help ensure that the WCRP Grand Science Challenges
would be addressed. Revised MIP proposals were requested
and evaluated by the CMIP Panel in summer 2015. The selection
of MIPs was based on the CMIP Panel’s evaluation
of ten endorsement criteria (Table 1). To ensure community
engagement, an important criterion was that enough modelling
groups (at least eight) were willing to perform all of
the MIP’s highest priority (Tier 1) experiments and providing
all the requested diagnostics needed to answer at least
one of its leading science questions
See table 1.
‘Steven,
What I’m suggesting is that the definition of BAU doesn’t necessarily change. That we are actually doing something doesn’t change that RCP8.5 is what we probably have followed if we had done, and continued to do, nothing. I can see, therefore, why some might still want to refer to RCP8.5 as BAU.
My own view is that we have to be slightly careful of conflating emission pathways and concentration pathways. There isn’t a one-to-one relationship between the two. As far as I’m aware, a concentration pathway close to RCP8.5 is still possible even if we follow an emission pathway typically associated with a lower concentration pathway. I’m not convinced, therefore, that RCP8.5 is no longer possible as a concentration pathway.”
Let me see if I can be clearer.
When a skeptic says ‘it could be otherwise” when they hand wave to explain the past, or
Gesture ( As tall guy does to some hypothetical scarcity) I want to say.. show me some detail.
Show me the story, Explain how all these worst cases happen together. yes yes I know it’s logically possible, but I dont think we need to waste precious wall time on the unlikely.
As I see 8.5 monkeys have to fly out of my butt and down tallguys throat before we will see
that scenario happen.
We already know RCP6 is a disaster. The whole world, save trump, believes that. The entire world is dedicated to staying below 2C. Countries are taking action. What will Policy learn from RCP 8.5 that it DOESNT LEARN from 7 or 6? or already know? I know science may learn a few things, but I’m not convinced you need to have a couple dozen centers running the extreme scenarios.
Steven,
im not convinced we know what the extremes are.
Historical predictions of resource availability and usage have often been drastically wrong in both directions.
Steven,
Yes, I agree. In fact, in my view, we already know enough to conclude that emission reductions are probably something we should be aiming to achieve. What I suspect, though, is that if we stop focusing on science (because we know enough) people will try to interpret that in ways that will undermine our ability to act.
Similarly, my impression is that many (although not all) of those who complain about RCP8.5 as BAU are doing so in order to them claim that we’ve already done enough (for example, “look, we’ve already done enough to avoid the worst”).
In some sense, what you say would be the case in an ideal world. We just present information that people interpret appropriately. However, we don’t actually live in that world and so sometimes we don’t end up doing what might be obvious. I can therefore see why we may want to continue focusing on a worst case scenario, even if that scenario is no longer as likely as it might once have been (to be clear, I’m always in favour of people being clear about this kind of thing, though).
Should I listen to tall guy or this guy?
https://www.bloomberg.com/news/articles/2017-05-24/misleading-coal-estimates-may-have-skewed-climate-projections
“Ritchie found that RCP 8.5, created for the most recent report, relies on two-decade-old coal assessments and assumes that within the next 20 years or so, other energy sources will fall away, leaving coal to pick up the slack. ”
Cue up unicorns and Butt monkeys
‘”This seems like a plausible emissions pathway to consider,” he said, “and perhaps the heavy use of coal is just a proxy for advances in high-carbon technologies that will enable this pathway,” such as tar sands or frozen methane sheets in the ocean called hydrates. ”
Perhaps monkeys.
“im not convinced we know what the extremes are.”
I have seen extreme prices for removal of C02 from the air.
I think they are extremely wrong, and they dont understand the extremes we can see in
technology advancement.
because extremes are unkownable we should use precious wall time to study an RCP -2.5C
because you know we might see some extreme tech that gets us extremely cheap removal of c02 from the air, and we will all be extremely happy.
Gosh that was fun.
Still comes the question: what do you learn from 8.5 that RCP 7 wont teach you?
Whether the monkeys off 8.5 jump out my butt or the squirrels of RCP7 jump out, each is painful
and will be avoided.
Unless we are insane, in which case, have a party
Steven,
What about how much we learn from a range of concentration pathways going from possibly unrealistically low to possibly unrealistically high (and, as I’ve said, I’m not convinced that we can yet really rule RCP8.5 out as a concentration pathway).
Click to access RFF-DP-16-45.pdf
‘What about how much we learn from a range of concentration pathways going from possibly unrealistically low to possibly unrealistically high (and, as I’ve said, I’m not convinced that we can yet really rule RCP8.5 out as a concentration pathway).”
Of course we cant rule it out. We cant rule out RCP – 2.. or RCP 23..
We can’t rule out unicorns or asteroid impacts or any manner of things we might want to
study or learn things from.
Instead are arguing that you can’t rule OUT RCP 8.5, explain in detail what has to happen
for RCP 8.5 to become a reality.
Increased coal use — as some suggest– is not gunna happen at a rate high enough for 8.5 to happen. There aint that much coal. And it would have to be economic coal since Solar and wind are getting cheaper and cheaper.. will people suddenly get stupid and pay more for power when they dont have to? monkeys.
Coal is dying. Kill it already, don’t let people think there is a remote possibility that all the nations of the world will go insane and burn 10x the coal we burn today
And if you think some other FF will take the place of coal… and get us to 8.5.. well name it.
and try to put numbers on it. And that name better not be monkeys.
Steven,
I really don’t think that RCP2.6 and RCP8.5 are in the same category as unicorns. They probably bracket a range that is highly realistic.
You haven’t really responded to my point that uncertainties in the carbon cycle (and potentially carbon cycle feedbacks) mean that we could follow an emission pathway normally associated with a lower concentration pathway and end up with something close to an RCP8.5 concentration pathway. I don’t think (even taking coal into account) that RCP8.5 is as unlikely as you seem to be suggesting.
Steven,
We are already mitigating
We are already moving away from FF.
In terms of actual mitigation so far, very minimal. Fossil fuel emissions have tracked with RCP8.5. What we have are very recent pledges to mitigate in future. And one of the most important countries has already reneged on that commitment.
if we continue this business as usual we will definiately not have RCP 8.5
That’s engaging in a form of circular reasoning. The whole point of baseline/BaU/no-mitigation scenarios is to give an idea of what happens if we don’t mitigate in order to inform decision-making. Obviously if we choose to mitigate, with that choice in part dependent on information from no-mitigation scenarios, the no-mitigation scenario shouldn’t happen. But that doesn’t change the inherent plausibility of the scenario at the time it was made.
To get 8.5 we have to hit the worst case population estimates
We don’t, in any meaning of that phrase. As noted already, A1F1 is an RCP8.5 scenario and produces a population at 2100 of 7.1 billion. That’s well below current forecasts.
The current UN population forecast has a 2100 best estimate of 11.2 billion with 95% range 9.6 to 13.2 billion. The particular scenario you’re talking about, which was used to represent RCP8.5, has 2100 population at 12 billion, comfortably within the uncertainty range. Furthermore, the UN forecast has been steadily trending upwards in annual revisions over the past several years as new demographic data has come in. In 2011 the best estimate was at 10.1 billion. If that continues, the best estimate will be 12 billion very shortly.
We have to reverse mitigation, and go whole hog for FF which is being defeated in the market
We basically have to go insane.
Have you taken a look who’s in the White House lately? Or at the EPA?
Notice how deftly Steven turned the conversation away from lukewarmers and their misrepresentations to a rope-a-dope about RCP 8.5. The man has chops, it must be said.
RCP8.5 likely range by 2081-2100 = 3.7oC ( 2.6-4.8)
Current commitments to the Paris climate change agreement = 2.6-4 oC
Cumulative emissions for RCP8.5 ~6000 GTCO2
Total Fossil Carbon available = ~3600-7100 (reserves) ~31000-50000 (resource)
RCP 8.5 doesn’t seem unachievable to me.
We are already 250GTCO2 through the 1000GTCO2 for the 2oC target (66% probability). Included optimistic targets for land use changes and cement production ~60GTCO2 and ~150GTCO2 respectively for the 21st century this leave ~540GTCO2. At current emission rates, 37GTCO2, we have 15 years worth of emissions remaining.
Politician: “why shouldn’t we reverse what minimal mitigation we have done so far and just went for fossil fuel driven growth without restraint”
Scientist: Here are the RCP8.5 projections.
Politician: “Ah, … O.K., perhaps we better not do that then”
Even if a scenario is unrealistic, doesn’t mean it doesn’t serve a useful purpose.
BBD –
Yup.
Not to mention throwing Ridley under the lukewarmerist bus. Ridley’s self-definition as a lukewarmer is no less “valid” as Steven’s self-identification as a lukewarmer. There are many self-identified lukewarmers who align with Ridley’s views.
Steven –
Perhaps you might focus some of your energy on explaining to lukewarmers why Ridley’s arguments are flawed?
Mosher:
”
Since they have included an RCP 7.0 for Ar6, I think that should tell you every disaster story we can hope to avoid.
”
Well, there you have it folks…
Thanks to monkeys-might-fly-out-of-my-butt science, we can say with high confidence that when disasters are stories, and every one of them is foretold by RCP 7.0, that Matt Ridley is not a member of The “lukewarmer” Team.
With Judith Curry’s expertise on sea-level rise, and Steven Mosher’s expertise on everything else, how can we possibly lose?
”
We basically have to go insane.
”
Are we there yet?
As traditionally used by ‘skeptics’, the word “alarmist” includes anyone who thinks ECS > 2.5. It easily encompasses the mainstream position of ECS = ~3.0.
As traditionally used by ‘skeptics’, the word “alarmist” includes anyone who thinks ECS might be >2.5, and that such a development would pise enough risk for harm that mitigation policies should be evaluated.
Only people who dismiss such risk (and who doomsay about the outcomes of mitigation policies) are considered non-alarmists.
We have been in the oil business since 1982. I think about 8.5. It would be a mistake to underestimate us. It always has been a mistake to underestimate us. There is simply a gigantic amount of FF inside of rocks. As is, would take way more energy to get it out than the rock can yield. Except, haha, with 12 billion people total, 8 billion could put around 4 billion into slavery breaking up rocks. Being cold will make you mean.
What The Rev said … +1
Good compromise for those that think RCP8.5 is too high. But now you’ve added an entirely new baseline, and IMHO, noone are going backwards with older models to recreate this new baseline condition for older CMIP’s/IPCC reports.
We also have a set of baseline conditions, RCP2.6,4.5,6. and 8.0 which will be constantly updated, so that we can see the modelling evolution with time as the models become more sophisticated.
The general rule of any type of experimental modelling is: Don’t change you’re baseline conditions ever. SM has very likely never conducted/lead either numerical, laboratory or prototype modeling, which all require at least one baseline condition.
Finally, it’s really GHGe that counts, and under that metric, RCP8.5 could happen under BAU (or we could pollute even more than BAU conditions (e. g. CH4 outgassing from fracking).
Perhaps we need an RCP10.0 (e. g. I see SM’s counteroffer and raise it with a higher counteroffer). End result, keep RCP8.5.
If one is going to do a driveby, expect others to do so. Dropping RCP8.5 would require some rather compelling peer reviewed consensus literature.
0 to 1.5C: Lunatics
1.5 to 4.5: Not insane
4.5+ : Alarmists
greater than 3.4°C: Insane ( twice the highest observed per doubling rate )
greater than 1.8°C: Anxious
1.8°C: Grounded. (highest observed thirty year per century trend)
1.7°C: Grounded. (latest observed per century trend)
1.7°C: Grounded. (observed transient per doubling rate)
1.0°C: Grounded. (Steffan Boltzman inversion, implying net feedback of zero)
less than 1.0°C: Ungrounded. (Assumes negative feedback)
less than 0.5°C: Insane.
TE,
You do understand that there is a difference between the transient response, and the equilibrium response, don’t you?
Already >1C for just 120ppm CO2 and TE thinks imagining ECS to be 1.8C to be ‘grounded’.
Jeez.
You do understand that there is a difference between the transient response, and the equilibrium response, don’t you?
You do understand that transient observations are testable, but ECS is not falsifiable, and hence a never rejectable point of speculation, don’t you?
I admit I have no idea how Cox et al methodology works but Cox is quoted as saying “Our study all but rules-out very low or very high climate sensitivities” – which seems a strong statement. The study may indeed show that but can we have confidence that this study is innately superior to others using other methodology, which do not “all but rule out” higher sensitivities?
Seems to me that we have experienced close to 1 degree of warming with a rise in CO2 of about 40% – but for current concentrations we still have warming in the pipeline, any equilibrium temperature will be higher. Also there is the aerosol component –
>The new study relied on four global climate models, which the researchers used to simulate the effects of removing all human-caused emissions of the major aerosols, including sulfate and carbon-based particles like soot. The resulting global warming, they concluded, would be anywhere from 0.5 to 1.1 degrees Celsius. (Samset et al “Climate impacts from a removal of anthropogenic aerosol emissions”).
Then there are carbon feedbacks, which (IIRC) are usually not included in climate models; we may not have a clear idea how much and how soon but seems highly likely they will add to warming. Or is that not counted because it’s purely about atmospheric concentrations and CO2 released from carbon feedbacks becomes part of the doubling of concentration?
It does seem to me we are not that far short of the 2.8 degree mid range/most likely figure Cox et al give for doubling of CO2 – but well before reaching that doubling. Am I way off mark here?
Turbulent Eddie:
Did… did you really just switch between ECS and current observed per-century temperature trends?
Wow.
It should be noted that these don’t even have the same units. One is the pseudo-equilibrium temperature change after a doubling in CO2, the other is the current change in temperature per time. They are not comparable, not even a little; you cannot swap these two.
America’s new worst-case scenario is an extinction event from the impact of an asteroid that goes undetected during a government shutdown .
https://vvattsupwiththat.blogspot.com/2018/01/like-undocumented-alien-that-killed.html
TE,
That doesn’t really answer my question, but never mind.
TE wrote “You do understand that transient observations are testable, but ECS is not falsifiable, and hence a never rejectable point of speculation, don’t you?”
Nice evasion. Of course ECS is falsifiable. If we double CO2 and see a centennial scale drop in temperatures, with no substantial changes in the other forcings that could explain it, then an ECS of e.g. 2 degrees per doubling is obviously falsified for anyone taking falsificationism seriously.
TE IMHO by evading ATTPs question, all you are doing is showing that you are not interested in what the science actually says and whether your position is actually tenable. Why do people do this? It is so transparent what is gained by it?
Perhaps here only mockery, but in the wider domain…
Let’s not pile on too much. I mostly regard TE as quite well informed. Disappointing when that doesn’t always seem to manifest itself.
ATTP indeed. I don’t think this is limited to discussions about climate, it seems pretty pervasive in on-line discussions in general. In a scientific discussion it ought to be taken as read that straight answers are given to direct questions (even if they are just intended to make sure both parties are on the same page).
“Taking delight in being shown to be wrong is one of the most important skills any human being, let alone a scientist, should develop” – Brian Cox and Jeff Forshaw – “Universal: A Journey Through the Cosmos”.
“ECS is not falsifiable”
With recent observations giving: 1) a TCR around 1.7, higher if arctic warming is captured better, 2) an global energy imbalance of around 0.8 W/m2, and 3) no natural factors for recent warming identified; an ECS <2 appears unlikely. Also the recent observed TCR and energy imbalance are well within the range predicted by climate models. So climate models are generally supported by recent observations, while many "blog science" theories are falsifiable.
Does anybody think the new ice core paper may eventually have some bearing one the ECS discussion?
Mean global ocean temperatures during the last glacial transition
New Study Identifies Thermometer for the Past Global Ocean
Rasmus chimes in…
A recent story in the Guardian claims that new calculations reduce the uncertainty associated with a global warming:
‘A revised calculation of how greenhouse gases drive up the planet’s temperature reduces the range of possible end-of-century outcomes by more than half, …”
It was based on a study recently published in Nature (Cox et al. 2018), however, I think its conclusions are premature.
The calculations in question involved both an over-simplification and a set of assumptions which limit their precision, if applied to Earth’s real climate system.
They provide a nice idealised and theoretical description, but they should not be interpreted as an accurate reflection of the real world.
There are nevertheless some interesting concepts presented in the analysis, such as the connection between climate sensitivity and the magnitude of natural variations.
The claim of reduced uncertainty for equilibrium climate sensitivity is premature by Rasmus Benestad, Real Climate, Jan 21, 2018
JH,
One of the authors has a response.
An interesting remark: We are attempting to do objective climate science, rather than to support a particular advocacy position, so direct communication would be greatly appreciated.
Any suggestions as to how to interpret it?
Joshua,
Unless I’m mistaken, there was an earlier comment that complained that (IIRC) both the Guardian and the Realclimate post were written without talking to the authors of the paper being critiqued. That comments seems to have disappeared, so maybe the end of the new one is a slightly subtler attempt to criticise the manner in which these critiques have been written.
Regarding ECS and the TCR.
About a year ago, I switched to the TCR from the ECS. One reason is I didn’t think I’d ever see the end results of the ECS. The TCR is more grounded for the same reasons it has been criticized for being too simple a thing to figure compared to the ECS. When we vote on a ECS range, we are further in the future and more inside of a black box calculation meaning most don’t understand it. It seems to me policy should be based on the TCR. To plan out 40 years in the future has risks and like almost all information 40 years in the future, the distance in time degrades the value of the plus 40 years information to be used for policy. This distance makes discussions of what it is, philosophical. As you build layer upon layer of math into the distant future, this construction allows doubt and its friend, belief into the question.
If they wanted to do ‘so called’ objective climate science they they MUST include the word OBJECTIVE in both the title and abstract of their paper (taken from the novel The World According to Lewis).
The reasons ECS is not falsifiable and merely speculative are:
1.) no one knows if or when equilibrium might occur – no state of past equilibrium is observed.
2.) neither satellite measurements nor even models of net solar appear in error by more than the amount of forcing from a CO2 doubling.
The AR4 made predictions on the basis of transient response ( low scenario 1.8C/century).
The AR5 avoided transient predictions in favor of nebulous ECS.
A cynic might imagine this was to avoid the low end results of observed response.
Beyond this, there are physical reasons to doubt response greater than what’s observed.
For response to be greater than Steffan-Boltzman response, there must be net positive feedback.
But the absence of the hot spot means the largest positive feedback, the water vapor feedback, is negligible since it coincides with the hot spot, as can be seen in Figure 2 of Soden and Held 2006.
I suspect that the peer review process of the Cox et al paper had its moments.
The ECS and the future. I am a CPA and am in my early tax preparation season and have been one since the early 1990s. I’ll be dealing with the new tax code, questions now, bottom lines in about a year from now. Did I predict what the tax code would be back in October? No. If I was in a different area of being a CPA, we’d find a few doing predictions on very short time frames. 1-5 years I suppose. The number of current and practicing CPAs saying anything about the year 2058 as a CPA is probably zero. Why is this? People would say, a CPA said it. They know about money. Later would be lawsuits when the predictions didn’t pan out and the plaintiffs would say, the guy is a CPA and I believed him.
The difference between CPAs and climate scientists is that they deal with physical systems. The variables are the emission pathways, plus a bunch of other stuff. And even presenting different outcomes based on different emission pathways still leaves us with a bunch of other stuff, and there’s the failure point. Even though the idea is to use GHG emissions as the control variable. You can see the other stuff in broad IPCC ranges for sea level rise. In explanations of Antarctic contributions to SLR. In their section on changes in extreme weather. So while there is a physical system, it is surrounded by jello and relations are not tight but mushy. And then projections or pick the name, are given.
Predictions about future market conditions involve people and what they’ll do and some examples of where things go off the rails is the numerous market crashes as well as the market interventions by governments. All materially influenced by human factors which defy being reduced to formulas. And climate scientists have the easier task with their formulas about a physical system. But they still have to deal with everything that makes most predictions have little value and sometimes negative value. CPAs have learned by experience if nothing else to keep predictions to very short time frames and emphasize uncertainties.
The ECS is I suppose about the GMST. What does that do for me? Very little. I live in Minnesota. What’s happening to our rainfall and growing season? Taking action on the ECS ignores Minnesota specifically and our rainfall, and growing seasons. Say I want to grow corn and a lot of it. GMST predictions tell me to save the world. But I want to grow corn in Minnesota. If we all save world, who is going to feed it?
Minnesota is not an island.
“However, the public debate seems to be dominated by those who think everything will be fine (Lukewarmers) and those who are mostly in the middle of the mainstream. In fact, there is often quite a lot of pushback against any who present worst case scenarios.”
–
?? Skeptics don’t exist or don’t debate.
–
-“The significance of these new studies to the public climate debate therefore seems to be that they largely rule out the Lukewarmer position. The more extreme scenarios (both low and high) may be less likely, but we can still potentially emit enough to warm substantially. In a sense, how much we will probably warm is largely unchanged.”
–
I see it more as a ruling out of irrational fear, Something Mosher has been alluding to.
Given that a low ECS is not a cause for concern ever we only have 3 degrees or 10 degrees to worry about.
3 degrees will take a long time and will be reversible with improving human knowledge and techniques before it can become a game changer.
10 degrees! now there is a go and hide in your refrigerator, the man with the hockey mask is coming moment. I am very glad it is being ruled out so we can concentrate on identifying the degree of threat and the ways to neutralize it.
TE,
Okay, now you are getting silly. You seem to be arguing that because we don’t know something with absolute precision, then it has no value/use. ECS clearly is potentially falsifiable, even if we can’t precisely know when we’d have reached equilibrium and there clearly are previous epochs when an external perturbation has driven the climate to an approximately new equilibrium (glacial cycles, for example). Given that you’re either less well-informed than I had thought, or no longer engaging in good faith, I’m not going to bother responding further.
Joshua asks: “An interesting remark: We are attempting to do objective climate science, rather than to support a particular advocacy position, so direct communication would be greatly appreciated.
Any suggestions as to how to interpret it?”
As an indictment of the blog debate on climate science (i.e. that you actually need to point out that is what scientists tend to do, at least in their science)?
ATTP the earlier comment seems to be there at the moment.
Dikran,
Ahh, thanks, I obviously didn’t look hard enough.
angech,
One day you might actually read one of my posts. A low ECS could still be a cause for concern if we emit enough. How much we warm (and, therefore, the impacts) depend on both climate sensitivity and how much we eventually emit. The more we ignore this, the more we are likely to emit, and the more even a low ECS would be a cause for concern.
TE it is a shame that you did not respond to the key point, which is that the observed warming to date only really sheds light on TCR rather than ECS.
The reasons ECS is not falsifiable and merely speculative are:
1.) no one knows if or when equilibrium might occur – no state of past equilibrium is observed.
2.) neither satellite measurements nor even models of net solar appear in error by more than the amount of forcing from a CO2 doubling.
I gave you the details of a test that would potentially falsify ECS. If you want to show that ECS is not falsifiable you need to demonstrate a flaw in that test, which you have not done.
TCR is similarly speculative
1.) nobody knows if or when CO2 levels will have doubled.
2.) would that not also affect TCR
3.) GHG forcing has not risen at 1% for 70 years, which is required by the formal definition of TCR.
4.) TCR relates to the forced response of the climate to GHG forcing. The observations are a mix of forced and unforced responses.
However, TCR values are nevertheless falsifiable. If we say TCR is 2C/doubling and over a period of 70 years of CO2 growth roughly in line with the definition, we see 2C of cooling, that would falsify a TCR of 2C/doubling.
Being a scientist doesn’t mean you need to abandon common sense in favour of strict formal definitions.
Err… I don’t think that is correct. ECS would be higher than TCR even without positive feedback because of the thermal inertia of the oceans. Temperatures would continue to rise slowly until the oceans had thermally equilibriated, which would take hundreds/thousands of years. I would have thought that very fast feedbacks, such as water vapour would affect TCR and ECS about equally (although I am no expert), but slow feedbacks (e.g. carbon cycle) will affect ECS more than TCR (obviously as they are slow with respect to what is considered “transient”).
I agree with ATTP that the discussion is getting silly, and it is hard to see it as in good faith as you have ignored repeatedly the original point.
“The reasons ECS is not falsifiable and merely speculative are:”
TE doesnt understand what Falsifiable means.
Do we need to rewind the tape?
Against the Excesses of idealistic philosophy the logical positivists ( Vienna circle )
Suggested a verification principle of meaning… Popper’s twist on the verification theory of meaning
was twofold. First to focus on falsification rather than verifiability ( or conformation) and second
to see the principle as a demarkation between Science and Non science rather than a demarcation between meaning and non meaning.
For a statement to be falsifiable it must have empirical content. it must be falsifiable in PRINCIPLE.
We can use a simple example: God is all knowing. England is an planet. In the second case we have clear emprical contect. We know how to check the truth of the statement and we can in fact check whether it is false. In the first statement, we might know what it means.. there’s this being that knows everything, but we would be hard pressed to specify a test of that. It’s untestable in principle. If I told you the sun would explode in 4 billion years, the empirical content is clear. 4 billion years from now that thing in the sky would blow up. The test plan is easy. Wait and watch. If 4.1 billion years go by and that thing is still around, well there you go.. falsifiable and falsified.
The statement “the sun will explode in 4B years” is thus a scientific statement. It is, in principle, capable of being found false. Yesterday I woke up at 623 AM. That’s meaningful, its empirical, its falsifiable in PRINCIPLE ( perhaps the hotel has spy cameras watching), but none of you can falsify it in practice.
I’m thinking of oranges now…..
haha
Use this to get some primary source material or read an encylopedia of philosophy.
https://en.wikipedia.org/wiki/Verificationism
Wel it looks as if I missed a classic set of posts here at ATTP … must have fallen asleep …
“It cant happen.
It cant happen.
And because wall time is fucking precious.
because it can’t happen and people misuse the results from it
Kill that one too then
Not gunna happen.
but if you asked me what I would call alarmist 4.5= would be it.
The people who use the ‘alarmist language” to describe the not insane, are the lunatics.
yes there are boogey men. and monkeys could fly out of my butt.
We basically have to go insane.
So ya, for scientific purposes we can study what happens if monkeys fly out of my butt and if the whole world goes more insane than trump.
And we can do RCP 7.0, in which 75% of the world goes bonkers.
coal use.
ya
monkeys
butt
exit
As I see 8.5 monkeys have to fly out of my butt and down tallguys throat before we will see that scenario happen.
We already know RCP6 is a disaster. The whole world, save trump, believes that.
Cue up unicorns and Butt monkeys
Perhaps monkeys.
Whether the monkeys off 8.5 jump out my butt or the squirrels of RCP7 jump out, each is painful and will be avoided.
Unless we are insane, in which case, have a party
We can’t rule out unicorns or asteroid impacts or any manner of things we might want to study or learn things from.
And that name better not be monkeys.”
Really good points, now if we could just get rid of RCP4.5 … because monkeys, butt, unicorns, trump, insane, bonkers, lunatics, squirrels, throat and party,
So we ditch RCP2.6, RCP6.0, RCP7.0, RCP8.5 and we just keep RCP4.5 which is alarmist.
Do I have that right? Just want to be sure. 😦
I’m an adaptation skeptic.
Missing the point.
ECS is not falsifiable because TOA radiative equilibrium may never occur!
Much is made of oceanic heat content uptake, which is certainly plausible.
But the oceanic input-or-output to the atmosphere can fluctuate internally over many scales.
“Therefore, the subsystems of the climate system are not always in equilibrium with each other, and not even in internal equilibrium.”
Even if ECS were to occur, we couldn’t tell, because observation of net shortwave is both too inaccurate and too imprecise to around 4W/m^2.
The IPCC AR4 did indicate a trend ( rather than ECS response ) for a low scenario of 1.8C.
That’s about what the most recent thirty year trend indicates:
TE,
I think you miss the point of falsifibility. Is it possible to show that the ECS is not what we estimate it to be. Yes, if we double atmospheric CO2 and we wait hundreds of years (and there were no major asteroid strikes, volcanoes, and the variation of the Sun was small) we could reject our ECS estimate if we warm by an amount that is not consistent with the estimate.
Yes, but not who you think is doing so.
Also, you really are missing the point. The ECS is really a metric. It’s an indication of how sensitive our climate is to radiative perturbations. Throwing it out because we probably wouldn’t run the kind of experiment that would allow us to test it, is not an argument for rejecting it as a metric.
> ECS is not falsifiable because TOA radiative equilibrium may never occur!
You keep using that word, Teddy, but it may not mean what you make it mean:
https://twitter.com/nevaudit/status/891755108358397953
This got me blocked by JimB, so mileage varies.
“Missing the point.”
No, the point is that recent observations don’t tell you much about ECS, they are more informative about TCR, so disbelieving high values of ECS on the basis of being twice as high as observational estimates (“greater than 3.4°C: Insane ( twice the highest observed per doubling rate )”) is a fundamentally flawed argument. You might want to substitute new arguments if you like, but scientific discussion requires an acknowledgement that the original reasoning was flawed if we are to make any progress. It is you that is missing that point.
“ECS is not falsifiable because TOA radiative equilibrium may never occur!”
SM is right, you don’t understand falsifiability. Falsificationism essentially says that good theories require that certain observations are forbidden if the theory is correct, the more the theory forbids, the better it is. It is only necessary that a set of observations can be specified that COULD happen which would show the theory is incorrect, not that you can devise an experiment that could reproduce those conditions on demand, nor that they can be obtained on a convenient timescale.
Having said which, I also said “Being a scientist doesn’t mean you need to abandon common sense in favour of strict formal definitions.” The test I gave does not require the TOA radiative equilibrium to have been established to show that an ECS of say 2C/doubling was falsified, common sense would be enough.
As I pointed out, the circumstances required in the definition of TCR aren’t exactly fulfilled either.
As Voltaire might say, common sense is not so common [sense 1] … , or indeed so common [sense 4].
The northern hemisphere warming rate would be closer to ECS than the global rate.
Less thermal inertia from the oceans.
This higher NH warming trend would suggest the lukewarmers wish of a ECS of 1.8 C is already ruled out .
The Global Climate System isn’t waiting on humans to figure out what the “real ECS” is. Time is not on our side.
Bigger, Faster Avalanches,Triggered by Climate Change by Kendra Pierre-Louis, Climate, New York Times, Jan 23, 2018
JH, nope never happened before…
JCH:
“Minnesota is not an island.”
NoDak and what happened to my choice, the Flickertails, is not an island. I think they are favor of climate change and more extreme lows passing over about Kansas and bringing Gulf moisture to your fields.
“Really good points, now if we could just get rid of RCP4.5 … because monkeys, butt, unicorns, trump, insane, bonkers, lunatics, squirrels, throat and party,’
1. RCP 8.5 has gotten more unlikely than when it was first run years ago.
2. If you try to rationalize it with actual bottoms up scenarios you cant get there, unless
you imagine some scary new FF, or do some other crazy fiddling.
3. The Ar6 version of Rcp 8.5 will teach you nothing scientificially or politically that the Ar5 version
hasnt already taught you.
4. The 8.5 world will never happen unless the entire world goes a little bit crazy In which case
we have more troubles than the climate.
5. RCP 7.0 has been added , if you absolutely think you need a story scarier than RCP6.
SM sez ..
Well then, write it up and submit it to a journal, then I might at least read it. I’ll still be an adaptation skeptic though.
Until that time, you’ll just have to wait to see what they do when AR7/CMIP7 is designed sometime in the mid-to-late 2020’s. 🙂
ATTP: New research that merits scrutiny and discussion — perhaps in a new OP.
Global temperature targets will be missed within decades unless carbon emissions reversed</strong<, News, University of Southampton, Jan 22, 2018
Statistical Inference with Emergent Constraints – Tapio Schneider
So I am going to wait for Dessler et al’s follow-on paper: 2.4 to 4.5.
Steven,
Unless I missed it, I don’t think you’ve yet addressed the point that uncertainties in the carbon cycle mean that we could end up with something close to an RCP8.5 concentration pathway, even if we follow an emission pathway typically associated with a lower concentration pathway.
I strongly suspect that the earnest discussion of TCR and ECS is an Angel/Pinhead ratio problem with very little pertinence for policy. No doubt those with a deeper understanding of the science will correct my error(s) but here is why.
ECS is a metric of interest to modellers that relates the amount of extra energy absorbed to the global mean surface temperature.
But the amount of energy absorbed is determined by the CO2 atmospheric levels and the resultant positive feedbacks. The CO2 levels are an effect caused by our cumulative emissions. The causal chain runs FROM the Joules gained to the GMST.
Not the other way round.
Extrapolating wildly (and probably inappropriately) from posts by Issac Held on GMST, local effects and climate sensitivity, I can see that ECS could be very low, less than 1C, if you can warm a small area of the globe up a lot. Because energy out is proportional to T^4 it would be possible to raise the temperature within the polar circles for 3 months of the year by ~20C and restore the Earths energy balance from a doubling of CO2.
(this approximation may be very inaccurate!)
The resultant global mean surface temperature is obviously an outcome of the amount of additional energy in Joules that is absorbed by the climate system. But there is no way at present to accurately predict how this will be expressed, or emitted, at the local level.
ECS could be below 1C IF that energy is all sequestered in the oceans because of the much greater thermal capacity compared to the land and atmosphere. The water-world model.
But to conclude that would be safer, or less dangerous than partitioning 10% or the energy into the land and air seems deeply misguided. To reduce ECS to such low levels requires profound changes in ocean circulations and resulting ecology that have just as much uncertain potential to disrupt the climate and ecology that our civilisational infrastructure depends on as a 3.4C rise.
What matters is the quantity of energy the system gains. speculation about how much that could raise GMST to restore the TOA energy balance ignores the inevitable change to the system (WHATEVER the global mean surface temperature) that is a part of the process that achieves that re-balance.
Agree with Everett that it’s hard to correct the misconceptions.
(1) the correct ocean model is an infinite box model, since thermal diffusion requires an infinite number of slabs (plus dispersion on diffusion provides more varied pathways)
(2) The TCR is really an effective TCR since the Nic Lewis’ of the world always conveniently overlook that other emitted GHG’s accompany the CO2
(3) The land global warming gives an indication of the actual ECS since land has a much lower heat capacity than the ocean.
Clear that the effective ECS is around 3C at the current time and this hasn’t changed since the original Charney report in ~1979. Haven’t really given this much thought for several years as there are more challenging problems in climate science than this no-brainer.
Paul,
As far as I’m aware, this is not true.
SM wrote “The 8.5 world will never happen unless the entire world goes a little bit crazy In which case we have more troubles than the climate. “
No sign of that in 2017, no sir, none whatsoever! ;o)
I think the point of 8.5 (and indeed A1FI before it) is so that the politicians have a scientific basis for what would happen if the world did get a little crazy. Given that there are some politicians that think climate change is a hoax and are doing their best to inhibit scientific research on the subject as well as practical action, even though 8.5 is unlikely to actually happen (although not as unlikely as I would wish), that doesn’t mean 8.5 isn’t serving a useful (and beneficial) political purpose.
Record Jump in 2014-2016 Temps Largest Since 1900
Heat generated by greenhouse gas emissions and stored in the Pacific Ocean was released by the 2015-2016 El Niño, UA geoscientists found.
They basically say the heat, .24 ℃, came out of the Northwest Pacific.
And yet, by the end of 2017 the OHC anomaly for 0 to 2000 meters is the highest in the record.
OHC:
OHC:
Something was holding the surface air temperature down, and I don’t think these ECS exercises have figured out by how much.
Of course Nic Lewis marginalizes the effects of the accompanying GHG’s. Same thing I asked almost 3 years ago on this blog:
“The second line of argument is that you demand that whenever Nic Lewis estimates a sensitivity for CO2, that he also provide a doubling sensitivity for methane, N2O, and all the other non-CO2 GHGs. He also needs to provide error bars for every one of these estimates. But first ask him why he doesn’t do this.”
Paul Pukite: You wrote (my bold):
Clear that the effective ECS is around 3C at the current time and this hasn’t changed since the original Charney report in ~1979. Haven’t really given this much thought for several years as there are more challenging problems in climate science than this no-brainer.
I wholeheartedly concur. Repeatedly engaging in never-ending discussions of ECS has a tremendous opportunity cost. Time is not on our side.
James Annan has a new blog on Cox.
Linky?
It’s not here. That’s the original post.
It’s at his blue skies blog.
Thanks!
Paul,
No, as far as I’m aware, you’re wrong. I think I recall that discussion from a few years ago. I doubt that it will be less irritating this time, than it was then.
izen:
“What matters is the quantity of energy the system gains. speculation about how much that could raise GMST to restore the TOA energy balance ignores the inevitable change to the system (WHATEVER the global mean surface temperature) that is a part of the process that achieves that re-balance. “
The GMST in the distant future because of the ECS, is the end of the story. Everything from now until then is the interesting part. The GMST now is supposed to hint at the ECS. And I think it’s also a measure of joules emissions to the TOA and the upper oceans. There is a, Look at this, It’s warmer component. That has a final result flavor to it. We told you so. But I think the enhanced joules emission aspect is under weighted. The Arctic warmed. Which given the low humidity there may not be such a bad thing. When it warmed in the past, the Arctic did about the same thing as it’s doing now. Not to relegate the Earth to inhospitable conditions but to cool it more than before. The GMST measures such changes, but doesn’t weight good ones and bad ones differently. And I think that’s also true of the ECS. Higher pressure on one side of a border pushes stuff to the other side of that border.
I predict the GMST will keep rising by a moderate amount and the Arctic will rise more than the average starting from a 5 year window average value ending today. The warming will be moderate as least resistance pathways to the TOA are used as well as oceans sinks. The climate system has already rearranged itself as shown by the OHC rise and the Arctic warming. As distance from the equilibrium of the 1950s increases, processes that the cool the Earth in the face of warming increase or I hope they do. Going along with me on this might be the difference between a sluggish helpless climate system or an adaptive resilient one.
The theme I am trying to be on is that the GMST and ECS are poor metrics off to the side veiling the real system mechanics. Assuming this is true, What is supposed to be communicated? We are given the 2.0 C target at least once a month. This might be frustrating. How are we supposed to describe things?
Here is another post about the estimates of narrower ECS ranges.
Ragnaar
No. See eg. Evans et al. (2018). The Eocene hothouse was characterised by notable polar amplification but that didn’t cool it down. The Eocene was a multimillion-year hot climate state. What seems likely is that we will experience greater polar warming over coming centuries than expected on the basis of current modelling, but it won’t offset the rise in GAT. Just as it didn’t during the Eocene.
Back of envelope calculation –
Current average global temperature rise since 1880 = 1.0C (Giss)
Warming in pipeline = 0.3 – 0.8C (Gavin Schmidt)
Masking by aerosols = 0.5 – 1.1C (Samset)
Warming at 40% CO2 above 1880 = 1.8 – 2.9C
I could be way off base here but the high end figure appears to already exceed the Cox midrange estimate of 2.8C for doubled CO2. The low end figure doesn’t, but I’m finding it hard to believe only 1 more degree will result from GHG rising from 400ppm to over 580ppm. Then there are carbon feedbacks. And there are the unforeseens.
@-Ragnaar
“The theme I am trying to be on is that the GMST and ECS are poor metrics off to the side veiling the real system mechanics. Assuming this is true, What is supposed to be communicated?”
That the system response to increased Joules is not confined to a rise in GMST. That the rise in GMST predicted from models/physics is the best we can do (at present) but it fails to capture the local impacts of the system mechanics.
More emphasis should be placed on the unknown impacts that will negatively affect the ecological infrastructure on which our agriculture depends, and the ~6000 years of environmental stability and limited extremes we have enjoyed since the Holocene maximum.
A closer watch, and greater emphasis, should be made on the magnitude and frequency of extreme events despite (or because?) of the difficulty in statistical terms of determining the significance of such occurrences. The past ‘natural’ incidence of such extremes should not be used to dismiss current events as ‘just more of the same’ but as an indication and a warning of what we could expect to happen with greater frequency and magnitude in the future.
This will of course be rejected as ‘Alarmist’.
The intensisty of hurricanes, storms, drought, floods, snowfall, heatwaves, and ocean current changes are going to be more important as factors requiring adaption, or avoidence by emission reduction than the eventual GMST from the ECS.
Eventually modelling may be able to project such local impacts and changes to ENSO, PDO etc, but until then TCR and ECS get all the attention not because of intrinsic importance but because we are limited to those metrics by our ability to calculate them.
Ken,
You have to be careful because aerosols are masking some of the potential warming, but there are also short-lived GHGs that will eventually decay. They roughly cancel, but the timescales are different (the aerosols would precipitate faster than the short-lived GHGs will decay).
Apart from the conservative media misrepresentations, it’s hard to see what the fuss is all about with Cox et al. It’s another study that suggests that ECS is likely too high to avoid significant warming unless emissions are abated. Whoa!
ATTP – I realised it was oversimplistic and I was surely missing essential elements, yet it looks like some low estimates for sensitivity are, given warming to date, already looking unlikely.
Ken,
Indeed, some of the lower estimates are indeed looking unlikely. However, at lot of the reasons for why regard the observationally-based estimates for ECS as probably being too low are related to more complex factors like non-linearities and forcing efficacies, not simply aerosols and short-lived GHGs.
Mother Nature may soon be impacting global suface temperature trends in a big way…
Magma swelled beneath the Mount Mayon volcano in the Philippines on Thursday and a column of ash more than a mile high spewed out, forcing 75,000 to flee. Officials are warning that a major eruption could happen any day now.
It’s the latest action in what’s already been a very rowdy week along the Ring of Fire, the geological region that follows the 25,000-mile perimeter of the Pacific Ocean and is home to 90 percent of the world’s earthquakes.
>A volcano in the Philippines is threatening a major eruption by Umair Irfan, Science & Health, Vox, Jan 25, 2018
BBD – yes, we know enough to know that failure to rein back emissions will have serious consequences – none of these climate sensitivity papers provide any basis for believing otherwise.
It’s really not that hard: always quote CO2E instead of CO2. Perhaps it’s my inability to have ever being able to find an instance of Nic Lewis mentioning CO2E, whereas everyone on the realist side does.
So if the sensitivity is defined by doubling of CO2E, then the sensitivity by doubling of CO2 is by mathematical definition automatically higher
X/ CO2E = X / (CO2 + others) < X / CO2
Look at the denominator
BBD:
The Holocene climatic optimum seems to have had a pleasant climate. That’s the Arctic I expect. Wikipedia tells us the distribution of warming seems like today’s.
I am not claiming a 100% offset. It’s the warmth that powers the system reorganization. So Arctic warming isn’t just to torment snowshoe hares before their demise. The Earth lucked out in having a reactive defense to climate change. Probably water and some other factors.
I thought I read that the Arctic is trading more air masses with the more Southern places because of global warming. In the last month we got at least one of those cold air masses. Assuming a warm one went North, how long to you think those joules hung around? I’m a big fan of Jennifer Francis. Bring on a wavy jetstream. Stuff has to move around so let’s go. North you go South, South you go North.
izen:
I thought this was good:
“…TCR and ECS get all the attention not because of intrinsic importance but because we are limited to those metrics by our ability to calculate them.”
So, to take the Lukewarmers side, Lukewarmers calculated them as well (Lewis and Curry I believe). Which is a little progress to the truth that Lukewarmers and skeptics don’t do much science and have zero of these:
“There are more than two dozen scientific institutions around the world that develop climate models, with each centre often building and refining several different models at the same time.”
But back to, What’s the message? No regrets policies. Aggressive changes without visable results, that’s just a set up. I am generally against that. One example of value added is fracking and the resulting natural gas.
Paul,
Climate sensitivity is defined in terms of a scenario in which the only change is atmospheric CO2. In reality, there are many other factors that contribute to the change in external forcing. To estimate climate sensitivity using observations one should take all these factors into account. Nic Lewis does this in his work. If you’re going to criticise his work, ideally criticise something he actually does, not something he doesn’t do.
Ragnaar
The HCO was a result of orbital dynamics delivering greater summer insolation at high north latitude than at present. It is irrelevant to the cause and spatial expression of modern CO2-forced warming. The HCO doesn’t support your notion that polar amplification will act as a negative feedback to anthropogenic forcing. Palaeoclimate behaviour shows that this will not be the case (eg. the reference you ignored).
There is nothing in palaeoclimate behaviour that supports the lukewarmer ‘argument’.
On RCP8.5, there are two completely separate issues at hand, which are often conflated by those arguing against:
1) Is it desirable and useful to investigate what could happen if we chose not to mitigate or to follow only very minimal mitigation?
2) Does RCP8.5 represent a reasonable representation of what could happen if made such a choice?
The answer to 1 is unequivocally “yes”. Steven Mosher appears to argue against that on the basis of recent international agreements on mitigation. However, we already have other very commonly used scenarios which can represent pathways should those commitments be followed, and at this very early stage some skepticism about how far commitments will be implemented is warranted, particularly following the withdrawal of the US. It would be very unwise at this point in time to lose sight of why we’re choosing to mitigate.
The answer to 2 is also “yes”, in the sense that it’s a pathway which fits within the literature for no-mitigation economic scenarios. It can be reasonably argued that it’s on the high side of the range, and therefore not truly representative, but then RCP6 is equally at the low end of that range so it makes sense for another scenario to probe the high end. From an adaptation planning perspective it’s also useful to have information relating to a plausible near-worst case scenario.
The arguments against the inherent plausibility (assuming no mitigation) of RCP8.5 are almost universally weak, generally amounting to little more than personal incredulity, which is a bad way to assess plausibility of what the future might look like. Arguments based on supply side limitation analyses of coal resources, such as the one Steven Mosher linked, at least provide some solidity, but are founded on some dubious assumptions and interpretations of historical information. One example, which seems to be a pervasive and highly consequential assumption in such literature, using a quote from the linked paper:
Thus much of the literature proceeds to assume total coal consumption cannot exceed current estimates of reserves, which is how they achieve these strong limitations. The problem is that the World Energy Council don’t just suggest this isn’t clearly the case, they stipulate that in fact the opposite is true:
Ragnaar wrote:
But back to, What’s the message? No regrets policies. Aggressive changes without visable results, that’s just a set up. I am generally against that. One example of value added is fracking and the resulting natural gas.
Please define what you mean by “value added”? Does it take into account the envrionmental impacts of fracking?
Yes there are risks with fracking. It’s probably a least worst choice. Natural gas combined with solar and wind turbines yields more value than without natural gas. Properly deployed natural gas provides some grid stability.
I’ve used the term value. Some examples are:
Smartphones
My work PC
My ’99 Ranger that started at about 10 below F (morning start) for half a week lately
My new furnace
A truckload of corn
A diesel engine
My 450 Honda Nighthawk
Renville County farmland
That lake outside my window
Walleyes
Bees
Wildflowers
Ragnaar wrote:
Yes there are risks with fracking. It’s probably a least worst choice.
The organization,Physicians for Social Responsibiliy (PSR) does not concur:
PSR Position Statement Calling for a Ban on Hydraulic Fracturing, May 2016
Gas as a hedge against renewables intermittency is a bridge to nowhere. Gas ensures that deep decarbonisation never happens (not to mention keeping the gas industry coffers filled for decades to come). The renewables sector needs to stop pretending that intermittency isn’t a thing and deal with it via PHES. Although this means the end of the ‘cheap renewables’ meme the industry is so very fond of peddling.
But I don’t think pumped hydro storage can be a primary solution either, last time I looked, anyway?
https://dothemath.ucsd.edu/2011/11/pump-up-the-storage/
The HCO seems similar to what we are approaching. It seems during the HCO the climate system retained more joules. We can ask the question how did it evolve then or ask how will it evolve now?
“However, most evidence suggests that the positive feedback effects outweigh the negative effects.”
“The balance of evidence suggests that positive feedbacks to global warming will likely dominate in the Arctic during the next 50 to 100 years.”
Seems uncertain with a 25% chance of being negative. The climate we had in 1850 didn’t all come together in the previous 100 years to an optimum as some grand finale. Negative feedbacks to both warming and cooling brought it there. That climate was not precariously balanced, held firmly and desperately in place by 280 ppm to prevent it from skittering off into an abyss.
Except that there’s a rather huge forcing in place now that wasn’t there in 1850 or the HCO, Swee’Pea.
Memo to self: It’s 2018. Don’t subscribe to “new comments” on tired threads.
rust
Thanks for the link. Interesting discussion, and sounding the same note I find myself stuck on these days:
There are conversations we need to have and are not having.
Ragnaar
If Arctic warming created a negative feedback then we’d still be stuck in the last glacial. Just think about it. Nothing in palaeoclimate behaviour supports lukewarmerism. Exactly the opposite, in fact.
On his FB page, Michael Mann linked to the following article about the Cox et al article. It’s well written.
How Sensitive Is Earth’s Climate to Carbon Dioxide Pollution? by Matt Smith, Seeker, Jan 30, 2018
Does Michael Le Page frequent this blog site?
No, the worst-case climate change futures haven’t been ruled out by Michael Le Page, New Scientist, Jan 19, 2018
Following JH’s lede …
Global Carbon Budget 2017
Click to access GCP_CarbonBudget_2017.pdf
(has useful up-to-date links)
LUH2 v2f
Click to access LUH2_v2f_README.pdf
Future scenarios included in this version (LUH2 v2f) are:
• SSP1 RCP2.6 (from IMAGE)
• SSP4 RCP3.4 (from GCAM)*
• SSP2 RCP4.5 (from MESSAGE-GLOBIOM)*
• SSP4 RCP6.0 (from GCAM)*
• SSP3 RCP7.0 (from AIM)
• SSP5 RCP8.5 (from REMIND-MAGPIE)
*Coming soon
A publication and DOI are also planned for this dataset.
http://luh.umd.edu/data.shtml
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