Climate Sensitivity Takes Another Tumble (via the GWPF)
Since [the publication of the IPCC’s] AR5, various papers concerning aerosol forcing have been published, without really narrowing down the uncertainty range. Aerosol forcing is extremely complex, and estimating it is very difficult. In this context, what is IMO a compelling new paper by Bjorn Stevens estimating aerosol forcing using multiple physically-based, observationally-constrained approaches is a game changer. –-Nic Lewis, Climate Audit, 19 March 2015
1) Climate Sensitivity Takes Another Tumble
Andrew Montford
Over at Climate Audit, Nic Lewis reports on the publication of a very important paper in Journal of Climate.
Bjorn Stevens has created a new estimate of the cooling effects of pollution (“aerosols”) on the climate. Readers will no doubt recall that to the extent that aerosol cooling is small the warming effect of carbon dioxide must also be small so that the two cancel out to match the observed temperature record. Only if aerosol cooling is large can the effect of carbon dioxide be large.
Stevens’ results suggest that the aerosol effect is even lower than the IPCC’s best estimates in AR5, which were themselves much lower than the numbers that were coming out of the climate models. He also suggests that the number is less uncertain than previously thought. This is therefore pretty important stuff.
Stevens chose not to calculate the effect on climate sensitivity but, being a helpful chap, Nic Lewis has done so for us, plugging the new numbers into the equations he recently used to calculate a decidedly low estimate of climate sensitivity and transient climate response based on the AR5 estimates. The effects, particularly on the upper bounds, are startling:
Compared with using the AR5 aerosol forcing estimates, the preferred ECS best estimate using an 1859–1882 base period reduces by 0.2°C to 1.45°C, with the TCR best estimate falling by 0.1°C to 1.21°C. More importantly, the upper 83% ECS bound comes down to 1.8°C and the 95% bound reduces dramatically – from 4.05°C to 2.2°C, below the ECS of all CMIP5 climate models except GISS-E2-R and inmcm4. Similarly, the upper 83% TCR bound falls to 1.45°C and the 95% bound is cut from 2.5°C to 1.65°C. Only a handful of CMIP5 models have TCRs below 1.65°C.
Remember folks, the IPCC’s official upper bound is 4.5°C, but Stevens’ results suggest that ECS can’t be above 1.8°C.
Jim Hansen, Bob Ward, Kevin Trenberth, Michael Mann and Gavin Schmidt, your climate alarmism just took one helluva beating.
2) The IPCC versus Stevens
Andrew Montford
I’ve updated Nic Lewis’s graph of his new climate sensitivity estimates by adding the IPCC’s likely range of 1.5°C–4.5°C as a grey box. Something of a contrast here I would say.
The situation for TCR is only marginally better.
3) The Implications For Climate Sensitivity Of Bjorn Stevens’ New Aerosol Forcing Paper
Nicholas Lewis
In a paper published last year (Lewis & Curry 2014), discussed here, Judith Curry and I derived best estimates for equilibrium/effective climate sensitivity (ECS) and transient climate response (TCR). At 1.64°C, our estimate for ECS was below all those exhibited by CMIP5 global climate models, and at 1.33°C for TCR, nearly all. However, our upper (95%) uncertainty bounds, at 4.05°C for ECS and 2.5°C for TCR, ruled out only a few CMIP5 climate models. The main reason was that they reflected the AR5 aerosol forcing best estimate and uncertainty range of −0.9 W/m2 (for 2011 vs 1750), with a 5–95% range of −1.9 to −0.1 W/m2. The strongly negative 5% bound of that aerosol forcing range accounts for the fairly high upper bounds on ECS and TCR estimates derived from AR5 forcing estimates.
The AR5 aerosol forcing best estimate and range reflect a compromise between satellite-instrumentation based estimates and estimates derived directly from global climate models. Although it is impracticable to estimate indirect aerosol forcing – that arising through aerosol-cloud interactions, which is particularly uncertain – without some involvement of climate models, observations can be used to constrain model estimates, with the resulting estimates generally being smaller and having narrower uncertainty ranges than those obtained directly from global climate models. Inverse estimates of aerosol forcing (derived by diagnosing the effects of aerosols on more easily estimated quantities, such as spatiotemporal surface temperature patterns) tended also to be smaller and less uncertain than those from climate models, but were disregarded in AR5.
Since AR5, various papers concerning aerosol forcing have been published, without really narrowing down the uncertainty range. Aerosol forcing is extremely complex, and estimating it is very difficult. One major problem is that indirect aerosol forcing has, approximately, a logarithmic relationship to aerosol levels. As a result, the change in aerosol forcing over the industrial period – anthropogenic aerosol forcing – is sensitive to the exact level of preindustrial aerosols (Carslaw et al 2013), and determining natural aerosol background levels is very difficult.
In this context, what is IMO a compelling new paper by Bjorn Stevens estimating aerosol forcing using multiple physically-based, observationally-constrained approaches is a game changer. Bjorn Stevens is Director of the Department ‘Atmosphere in the Earth System’ at the MPI for Meteorology in Hamburg. Stevens is an expert on cloud processes and their role in the general circulation and climate change. Through the introduction of new constraints arising from the time history of forcing and asymmetries in Earth’s energy budget, Stevens derives a lower limit for total aerosol forcing, from 1750 to recent years, of −1.0 W/m2.
Although there is no best estimate given in the published paper, it can be worked out (from the uncertainty analyses given) to be −0.5 W/m2, and a time series for it derived from an analytical fit used in the analysis. An upper bound of −0.3 W/m2 is also given, but that comes from an earlier study (Murphy et al., 2009) rather than being a new estimate.
I have re-run the Lewis & Curry 2014 calculations using aerosol forcing estimates in line with the analysis in the Stevens paper (see Appendix) substituted for the AR5 estimates. I’ve accepted the Murphy et al (2009) upper bound of −0.3 W/m2 adopted by Stevens despite, IMO, the AR5 upper bound of −0.1 W/m2 being more consistent with the error distribution assumptions in his paper.
The Lewis & Curry 2014 energy budget study involves comparing, between a base and a final period, changes in global mean surface temperature (GMST) with changes in effective radiative forcing and – for ECS only – in the rate of ocean etc. climate system heat uptake. The preferred pairing was 1859–1882 with 1995–2011, the longest early and late periods free of significant volcanic activity. These periods are well matched for influence from internal variability and provide the largest change in forcing (and hence the narrowest uncertainty ranges). Neither the original Lewis & Curry 2014 ECS and TCR estimates nor the new estimates are significantly influenced by the low increase in surface warming this century.
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rgbatduke
How do you square your contention that CO2 causes temperature increase, even small, with the geologic record which does not show any such causation? The Vostok ice core record confirms the long term geologic lack of causation correlation and shows clearly that for the past 1/2 million years CO2 follows temperature by 800-1000 years. Could one not argue just as logically that current rising CO2 is due to the Medieval Warm Period and is unrelated to current temperatures and the picayune amounts of CO2 human activities are adding to the total?
Exactly the same thought occurred to me. I’m quite sure the basic physics is correct, and that CO2 will cause warming in the laboratory. But we’re talking about the climate system, where everything is a function of everything else.
Fortunately for us, Nature has been performing its own laboratory experiments for millions of years and recording the results in the ice cores. As far as I’m aware, there is absolutely no evidence of CO2 changes causing corresponding temperature changes according to AGW. If Nature’s laboratory experiment shows no AGW effect then it’s not happening. Unless anyone can show contrary evidence, then the ice core data shows that the sensitivity is well under one degree C and probably close to zero.
Chris
There is evidence of CO2 as a forcing. It is confirmed by repeatable lab experiments and the recent Nature paper actually observed the effect in the field. It works, in simplistic terms, because light goes right through CO2, but a little bit of the upwelling heat wave is absorbed and reflected in a random direction, some of it across and down.
So much of the CAGW hype is caused by the 18-yr warming spurt which occurred between 1980 and 1998.
During this short 18-year window, the following natural phenomenon took place:
1) A 30-yr warm PDO cycle started in 1978.
2) A 30-yr warm AMO cycle stared in 1994.
3) The 2nd and 3rd strongest back-to-back solar cycles in thousands of years occurred between 1976~1996.
4) These last two strong solar cycles marked the end of the strongest 63-yr string (1933~1996) of solar cycles in 11,400 years (Solanki et al 2003).
5) There were a stream of SIX El Nino events between 1983~1998, including the Super El Nino event of 97/98.
Even with all these natural warm phenomenon occurring, the CAGW Warmunists still claim CO2 was the primary driver of the 1980~1998 warming spurt, which isn’t logical.
Since 1998, the complete opposite is occurring with these natural phenomenon:
1) A 30-yr cool PDO cycle started in 2008.
2) The 30-yr AMO warm cycle peaked in 2007 and will enter a 30-yr AMO cool cycle around 2024.
3) Solar cycles have been crashing since 1996, and the current solar cycle is the weakest since 1906.
4) Since the Umbral Magnetic Field is crashing (the force that holds sunspots together) there is a chance an 80-yr Grand Solar Minimum could start from the next solar cycle beginning around 2022.
5) There have only been TWO El Nino events since 1998, plus the weak 2014 El Nada event.
Despite 30% of ALL manmade CO2 emissions since 1750 being emitted over the last 19 years, there hasn’t been a global warming trend for 19 years:
http://www.woodfortrees.org/plot/rss/from:1996.6/plot/rss/from:1996.6/trend/plot/esrl-co2/from:1996.6/normalise/trend/plot/esrl-co2/from:1996.6/normalise
The longer this flat/falling global temp continues, the lower the probability that CO2 is a major contributor to global warming, and the lower ECS projections will become.
In about 5~7 years, the discrepancies between CAGW model projections vs. reality will exceed 3+ standard deviations, which should be sufficient discrepancy and duration (almost 25 years) to toss the CAGW hypothesis in the trash bin of history.
Every year from now, more and more peer-reviewed papers like this one are likely to be released with lower and lower ECS estimates. There is no way the CAGW hypothesis can survive the overwhelming empirical evidence that show CO2 forcing is a very weak forcing effect that could be as much as 10 TIMES LESS than CAGW projections.
Well said, but may pick a nit? Surely it’s La Nada. El Niño, La Niña, La Nada, which is a feminine noun meaning “nothingness” or “the void”, but can mean “nowhere” in some cases, as in “That car came out of nowhere!” (¡Eso auto vino de la nada!)
The Italian equivalents, “niente” and “nulla” are masculine, as are Portuguese “nada” and French “rien”. That’s right, it’s “o nada” in Portugal but “la nada” in Castile (but not everywhere in Spain, since Galician, the ancestor of Portuguese, also says “o nada”; Catalan is complicated; I won’t go there, Catalonia, yes, the grammar, no). The Latin word “nihil” is genderless. Latin has three genders, but no articles.
I got a nice used El Nado Dorado you’d look good in. Kick the tires.
======================
It’s okay. An El Nada is, by nature, an androgyne.
This article is an excellent example of the comment sections of this site where reasoning and evidence is a primary component with a bit of hyperbole thrown in. In the public discussion of climate, reasoning and evidence is not considered necessary because:
A.) The science is settled
B.) The deniers are a tiny faction of nutters.
It is hard to argue a point in the public arena when those two suppositions are the starting point. As a matter of fact you are not allowed to make an argument since A and B above precludes your ability to do so. As a political matter before progress can be made in public affairs we have to add:
C.) There is no credible or reasonable evidence for A and B above
Until C gains more traction we will have agencies like the EPA declaring CO2 a pollutant and attempting to gut coal energy, which has the unfortunate effect of increasing the price of energy and consequentially the cost of living and producing.
I follow Lindzen & Choi’s climate sensitivity of 0.67 C based on ERBE satellite data. Strong negative feedback possibly from clouds.
http://www.drroyspencer.com/Lindzen-and-Choi-GRL-2009.pdf
Dr. S,
Yes, that seems to be the closest number to the observed temperature changes. I’m happy to go with ⅔ of a degree C of global warming per doubling of CO2.
First, there probably isn’t enough usable fossil fuel to double CO2 from current levels, and second, even if CO2 did double, 0.67º more warming would be entirely beneficial.
Looks like the ‘pause’ is well and truly over, not that there was one really!
Arctic sea ice extent hits record low for winter
‘Sea ice in the Arctic Ocean has fallen to the lowest recorded level for the winter season, according to US scientists. The maximum this year was 14.5 million sq km, said the National Snow and Ice Data Center at the University of Colorado in Boulder.
This is the lowest since 1979, when satellite records began. A recent study found that Arctic sea ice had thinned by 65% between 1975 and 2012.’
http://www.bbc.co.uk/news/science-environment-31976749
blackadder says:
Looks like the ‘pause’ is well and truly over…
Where’s your data?
Dr. Spencer’s latest global temperature data (UAH) shows no such thing.
According to AGW theory, C02 can not create heat despite a cooling turn, rather it traps heat present in the system. So it is argued that, do to the solar cycle, we aught to see more cooling, which is offset slightly via C02 forcing. This is logic.
I can’t argue the logic, and because the variables are unknown I can’t support the initial AGW assertions
Well, let’s try this; oceans are large bodies of water with many massive layers each subject to fluidics, geographical features and so on. We have observed that the oceans are not constant in their flow and general behavior. The heat draw and output also changes…like the water in your bathtub is you had a fluctuating heat source in play. Now imagine that while we have observed the oceans change drastically over time, we have no credible survey mechanisms in place to say exactly why the oceans change…or osculate. We do know that they trap heat, they release heat…we can generally predict where this happens. so to say that a melting body of ice has anything at all to do with the global climate really misses the point. Local temps and affects vary greatly regionally, I thought we wer me all aware of this?
https://stevengoddard.wordpress.com/2015/03/22/visualizing-the-arctic-meltdown-since-2005/
What happened to the pictures/graphs/diagrams in the original post, or is it just my reception that is screwed up???
CO2 absorbes lwir to it’s capacity to do so. lwir is then emmited wth a lapse rate of what. A pico second? How is this secondary effect thermalized? Where is this heat? A thermometer tells me the temp but not where it came from.
Should read, not where the HEAT came from.
So far I have not seen any critiques of this paper from the usual warmist suspects. Has anyone seen any mention of it on the pro side of the blogosphere? I would be interested to read the critiques.
have a listen from the 21 minute mark about ‘consensus. interesting its all about the $$$$
regards’
Good video. An important point about consensus was, if you are with the consensus and you are wrong then you are forgiven. If you are not with the consensus and you are wrong you are fired. So it’s best to be with the consensus.
Brandon, you intrigue me. You say you do not actually do science yourself and yet you bring up detailed observations of climate science and huge caches of potentially valuable data. Clearly you have science-connected friends in the global warming camp or else you are independently wealthy and have employed them to bolster your views. I have to thank you for producing the data but unfortunately getting some use out of it is an extremely laborious process. Could you influence (or order) those science guys of yours to write it up in English? A step forward would be to take those maps showing locations of corrections and attaching the correction value to each location. But be that as it may be, I don’t like your response to my remark about volcanic cooling built into the CMIP3 code. Neither CMIP3 nor any of its friends has never been able to reproduce the actual global temperatures and should be shut down. You are also going all out with a “show and tell” response which is not what it is about. I knew it was just a short remark that you would not have understood without reading my book,But nevertheless you took me up on it. So let me give you the background now. First, volcanic cooling does not exist and any coolng built into the code is is simply wrong. But what particularly annoyed me about CMIP5 was that in addition to Pinatubo “cooling,” which is observable, they also included an imaginary El Chichon cooling that does not exist in the real world. They are both in CMIP5 output. The story with volcanic cooling is that every volcanic “cooling” in global temperature curves is nothing more than a misidentified La Nina valley. For reasons unknown people do mot know that the sawtooth pattern in global temperature curves is a concatenation of densely packed El Nino peaks with La Nina valleys separating them. It was created by the ENSO oscillation. ENSO has been at it ever since the Panamanian seaway closed. Volcanic eruptions are not synchronized with ENSO phases and an eruption can coincide with any ENSO phase. If it coincides with an El Nino peak it will be followed by a La Nina valley that is quickly acquired by the “experts” as a volcanic cooling. But when it coincides with a La Nina valley it will be followed by an El Nino warm peak and the experts are left scratching their heads about where the cooling went. Pinatubo is of the first type and is followed by a “volcanic” cooling that is nothing but a La Nina valley. El Chichon is the second type and it simply lacks its very own cooling, thanks to an El Nino looking down at it. Despite being ignorant of all this the “experts” like to stretch it. Take Pinatubo – it erupted in 1991 but they want to make it responsible for flooding in 1993 as well as for the Sahel drought. Let me put it this way: stupidity annoys me, especially if all they had to do to understand it was to read my book. I guess climate scientists are simply not the literary type. By the way, your trend lines are another stupidity that just sullies the waters. If you want to outline a trend, use a broad semi-transparent, colored marker as I did in my figure 15. Some explanation is found at the beginning of my book and if you practice you will begin to recognize what the real trend is actually doing. Once you get to that point, mark the locations of global mean temperature and then connect the dots. As to the relative heights of the super El Nino of 1998 and the El Nino of 2010, they are both in my figure 15. And when you say, justifiably, that “… I don’t publish temperatures, but I do look at the data. The 2010 El Nino does NOT stand higher than the 1998 event:?” I whole-heartedly agree. But the temperature chart you show is not the same one that shows the effect. It was a HadCRUT4 as I recall and in it 2010 and 2014 were both higher than 1998. 2014 was also a shade higher than 2010 and got that “warmest ever” prize. Talk of stuffing the ballot box of global warming wannabees. It is this kind of stuff that makes them deny the lack of warming (80s-90s) on the one hand and then fabricating a non-existent warming for the next century (2014) that makes these warmists so objectionable. If I were you I would change my attitude and take a more positive view of WUWT who are almost the only people fighting it. Remember that our national climate policy depends on making these data accurate.
I just wanted to add my +1 to rgb. Awesome stuff, sir!