I have a question about stratospheric cooling. If the stratosphere is cooling because of both ozone loss and an enhanced tropospheric greenhouse effect, is there any way to assign proportional blame to these two factors? How much cooling is from ozone loss and how much is from more heat being trapped in lower layers of the atmosphere? Does the amount of cooling attributable to each factor vary with latitude and altitude? Is there a reliable source on the web for this information? Also, do the greenhouse properties of CFCs warm the stratosphere and offset any cooling from the loss of ozone?
If you block heat from escaping from the troposphere by adding GHG’s then the area above it would be cooler. sort of like living in a two story house and closing some heat vents that go up to the top floor. More heat downstairs, less heat upstairs.
Hope that helps.
[Response: No, this is not correct (think about what occurs at equilibrium where the net flux changes must be zero. The stratospheric cooling because of increasing CO2 is a function of the spectral nature of the absorption and the presence of other emitters in the lower atmosphere. – gavin]
You are right, it would be a lot of work. I try on the OSS site to bring in together and ref. to source. That of course is also done in the RC posts.
Spaceman Spiffsays
@197: Brian Schmidt:
The last of these topics (if I understand your question) was covered in a recent RC post, and I will try to reproduce the gist of it here. The collisional rates between C02 and other molecules exceed the radiative rates of C02 by orders of magnitude, at least in the densest portions of the lower atmosphere, where local thermodynamic equilibrium is a good approximation. Typical collisions then result in de-excitation of the radiatively excited CO2 molecules, so that the collision is inelastic kinetic energy-wise. As the density drops with altitude, the collision rates drop off and radiative de-excitation becomes important. One of the experts can fill in the gaps.
Mikesays
26 *So what’s the best response to the people who are saying loudly this morning that yesteday’s north-eastern record snow proves there is no such thing as global warming?*
One might hazard the guess that
(A) increased global temperatures result in increased evaporation from the oceans aand more frequent precipitation events i.re. more snow or rain and more vioolent rainstorms and snowstorms. These would be more likely to occur over certain areas where air masses converge – especially the mid latitudes.
(B) Increased retention of energy of ultimately solar origin in the increasingly carbon rich atmosphere results in a high proportion of that energy being trtansferred to e.g. the Greenland ice cap where it causes melting and the storage of latent heat in the meltwaters. This means that from the polar regions there
will be increased probability of incursions of relatively cool air masses into lower latitudes, bringing chill weather and snowfall.
Edward Greischsays
156 Spaceman Spiff: What I am saying, then, is that either way, we are toast. The climate can be sent into catastrophe by several mechanisms. I can’t give you a better answer.
Doug Bostromsays
Comment by Curmudgeon Cynic — 21 December 2009 @ 11:11 AM
Regarding ships displacing sea water, stimulation of oil fields, you might be interested in the role dam construction has played in the twentieth century.
Calculating the total volume of new impoundments filled during the past 100 years reveals a probable temporary masking of anthropogenic sea level increase, on the order of ~0.5mm/year, for a total effect of some 30mm.
Astounding, really, yet based on fairly reliable data.
Of course this is a -temporary- effect. As new dams are filled and the bulk of available sites are exploited, this effect will diminish.
Where can I get a year by year table of global temperatures for all the met offices that are collating such averages? All I can find are graphs with poor resolution. I’d like a resource on RC that collates and updates all the info every year.
Ron Kentsays
Heat of Fusion: As a PhD organic chemist, my training exposed me to some thermodynamics and a modest understanding of the physics of water phase transitions. When I hear arguments skeptical of even the existence of global warming based on quibbles over global temperature data, my inclination is to insist that simple recognition of widespread ice melting alone is sufficient proof of a significant change in the earth’s heat balance. Further, I suspect the basic fact that the ice – water transition occurs with no change in temperature may well contribute to an explanation of why ocean temperatures can show limited change or even decrease locally during melting. Are these lines of reasoning sound from the perspective of knowledgeable climate scientists?
Peak Oil: This has more to do with politics and policy than with climate science, but I’m hoping to recruit supporters for my idea – or learn why I’m all wet. My thinking goes as follows:
Conservatives are resistant to anthropogenic global warming (AGW) because proposed corrective actions impose great costs with poor assurance they will be effective. The root of the resistance is uncertainty in the extent of climate impacts and uncertainty in our ability to prevent them. At the same time, we face a much more easily understood issue encapsulated by the term peak oil – the growing disparity between global crude oil production and world demand. I see it as being much easier for laymen and businessmen to grasp the economic impact of rapidly growing costs and sporadic shortfalls of petroleum products than it is to understand the dire projections of AGW. Businessmen especially can recognize the consequences of an annual growth rate of even as little as 1% in the difference between supply and demand and just about everyone today has memories of the gas lines and material allocations of the 70s and the effect of the recent speculative spike in oil price. The corrective actions that address peak oil – conservation, increased energy efficiency, reduction in petroleum dependence, alternative fuels, etc – are also a big component of any program to address AGW. So my point is if there’s an urgent need for action instead of fighting AGW deniers we’re better off focusing on convincing laymen and corporations alike of the need to take these actions in the name of peak oil, not AGW. The truth is a majority of the petroleum industry has already accepted the peak oil scenario. If, as Senator Inhofe claims, AGW turns out to be a sham then there’s no loss. If experience shows AGW is real, we’re already started on the program we need and we have justification to expand it.
This rationale is based partly on my impression that the timeframe for dire peak oil effects is shorter than that for AGW. I foresee peak oil economics within 10-20 years whereas I expect AGW impacts of comparable magnitude are farther out.
Ray Ladburysays
Rotten Ham,
My understanding is that stratospheric cooling due to ozone loss would be maximum around 20 km, while greenhouse-induced stratospheric cooling is predicted to be in the 40-50 km range. This is precisely what is observed. Here’s a pretty good summary:
Are there others, other than Svensmark, that would fit well into this category? If so a list of those that should ‘show the code’ would be a follow up as it becomes appropriate.
Joel Shoresays
Blair Dowden (#174) says: “Carbon dioxide levels have been much higher in the past, particularly during the Cretaceous. Yet there is a lot of evidence for Cretaceous coral reefs, and a lot of limestone and chalk deposits, as a visit to the south coast of England demonstrates. The explanation I have heard is that is because the rapid rate of carbon dioxide increase means the ocean does not have time to transfer the carbon dioxide to the deep ocean, so the surface gets acidified.”
Actually, as I understand it (and someone can correct me if I am wrong), the timescale issue is not so much associated with the transfer of CO2 to the deep ocean but is instead associated with the rate at which limestone can be leached from the land into the ocean where it can neutralize the acidification caused by the CO2. Also, this timescale issue works in the opposite way than you have proposed: When the change is slow enough, the ocean ends up not becoming more acidic because there is time for the neutralization processes to occur (as opposed to your point-of-view that when the change is slow enough, there is sufficient time for acidification to occur).
So, the Cretaceous did not have a strongly acidic ocean simply because there was enough time associated with the rise in CO2 levels that there was time for the limestone leaching to neutralize the increased acidity associated with a rise in CO2 in the oceans. At the PETM event, where there seems to have been a quite rapid increase in CO2 levels, there is evidence for significant acidification of the ocean. And, some combination of this acidification and the climate change (and maybe other effects?) caused a quite dramatic extinction event.
A couple of things to remember. Coral now is very different from what it was in the Cretaceous. Also, the carbon cycle then was a lot faster than it is now.
Charly Cadousays
Rephrasing my question: do you think the science is settled? So what is the purpose of the CERN CLOUD experiment. Also notice that Svensmark is not that popular around this blog. Too bad, he seems like someone who thinks hard about the science.
[Response: New rules: #1. No-one is allowed to ask whether the ‘science is settled‘ because there are still papers published or experiments done. #2. Nobody gets credit for ‘appearing to think hard’ – when what matters is whether you think logically – irrespective of how hard that might be for you. – gavin]
Blair Dowden says:
21 December 2009 at 1:07 PM
I never questioned if global warming is happening, and in fact confirmed it in the next sentence. As for the Cretaceous issue, thanks for the suggestion, but somehow I doubt that thousands of organisms all simultaneously evolved a new method of fixing calcium carbonate. I am sure the answer, if known, is much more complex than that.
You might find some references here. You’ll see that in times of previous global greenhouse climate conditions sea water chemistry were times of calcite seas whereas to the present we are in the aragonite sea mode. http://en.wikipedia.org/wiki/Calcite_sea
Nick Bonesays
Gavin,
I’d like some discussion on your recent paper with Lunt, Haywood et al:
“Earth system sensitivity inferred from Pliocene modelling and data”. In particular, the high level conclusion that Earth system sensitivity is around 30-50% greater than Charney sensitivity.
A couple of questions arising from this:
1. How does this compare to Hansen et al’s estimate in “Target Atmospheric CO2 – Where Should Humanity Aim?”. Namely that Earth System Sensitivity is approximately double Charney (fast feedback) sensitivity, based on the Last Glacial Maximum. Why does the Plicoene estimate differ from this?
2. What does the Pliocene climate imply about Hansen’s 350 ppm target? My initial concern is that it would still be too high as a long-term stablilization target, because:
i) 350 ppm results in around 1 degree warming based on fast feedbacks,
so maybe 1.5-2 degrees of warming based on the slow feedbacks (admittedly over several centuries).
ii) The slow feedbacks would still imply a return to something like the Pliocene world with sea levels maybe 6-9 metres higher than today. In practice, that means sea levels continually rising by 1-2 meters per century for the next few centuries until the slow feedbacks are complete (and continual inundation of coastal cities, beaches, tidal zones etc. throughout that period).
Surely this constitues “dangerous” climate change?
3. Given the shambles in Copenhagen, what are the real long-term implications? What are the options for us getting back below 350ppm if we continue to overshoot massively into the middle of the 21st century? Should we be considering air capture, biochar or even more radical measures (foresting deserts, trying to dump alkili or limestone in the oceans etc)? Could we get right back to early industrial or pre-industrial levels, which is what we seem to need? What is the fastest we could reduce CO2 by such means, and do we have long enough?
Thanks,
Nick
John Masheysays
re: Peak Oil
I suggest not going there, espe. In any case, Peak Coal (natural, or via regulation) is likely a lot more relevant. Perhaps, every once in a while, if there is a good paper that combines improved models of fossil fuel resources and climate, that might be worth a mention.
Thorsays
I would like to see a good scientific writeup of how and why tree rings respond in a linear fashion to temperature. I guess this must include a discussion of both density and width of early and late wood as well as the importance of the trees micro climate. The writeup should also describe how different species might respond differently as well as any caveats and limitations when using tree rings as a temperature proxy.
Hi, I have a quick question about the data used by CRU and GISS for their global temperature calculations. Do they largely use the same raw data? I’m aware of the differences re the arctic temperatures, are there other major differences in the way they calculate global temperatures?
Andysays
I’d like to see more posts on the evidence that global warming and loss of artic sea ice may cause changes in Hadley Circulation Cells, atmospheric occillations, etc. See this article abstract as an example of perhaps unexpected climactic changes caused by AGW.
Doug Bostrom (209) — That number needs to be offset by groundwater removal.
gary thompsonsays
i think you should post a graph showing what the temperatures will look like for 2010. since you obviously have it all figured out and understand the earth’s weather system on a fundamental level, prove it. give monthly predictions with error bars and then track your score through the year. If your models are accurate then put them to the test. will 2010 be hotter than 2009?
Spaceman Spiffsays
@208 Edward Greisch:
Thanks for your reply. I certainly realize the toast part, but I was interested in the potential differences from an academic point of view. I suppose, as you indicate, we can use the catastrophic volcanic events to compare to what we’re trying to do…
Bob Arningsays
For the benefit of the statistically-challenged among us, perhaps you could comment on:
Does this curvy line (making climate look like it’s going nowhere in particular) have some value compared to the linear trends we often see associated with climate data.
It’s going to be harder to devise an effective simple communication analogue for that.
I will review the troposphere posts again. If I can get it visualized properly in my head I can develop better analogues. I’m just not there yet. Absorption ad different frequencies in the spectrum are not something I have assimilated well, yet.
Can cooling due to ozone still be illustrated by saying the stratospheric vents are left open to the troposphere allowing more IR to penetrate downward and not agitate as much in the stratosphere?
But it still seems though that the greenhouse effect can be described in part by closing some upward vents? Maybe each blocked frequency needs to be considered a different vent for my analogue?
In my mind, this raises a question. Has the mean altitude of a relative equilibrium state changed? Then has it become lower and by how much? I apologize as I’m still unsure what I am asking and trying to get a better picture in my head.
If the stratosphere emits radiates more heat into space, then maybe the picture is a roof with more holes than the floor below being more solid (troposphere)?
It also looks like there are two different floors, the ozone floor and the Co2 floor. So maybe for my analogue I need two houses?
Any help here would be appreciated :) I have been wanting to update my troposphere page for a while, but I don’t have enough confidence yet.
Another request for the New Year, inspired by the mysterious spectral nature of Gavin’s inline #204:
The Ultimate How and Why of CO2-induced Stratospheric Cooling for Dummies (that is, With Very Little Math)
OK, I understand why you might prefer to gnaw off your leg than have another go at this. I have checked out Gavin’s attempts here as well as Stoat’s, Eli’s, and Dr. Uherek’s ESPERE page, all somewhat different. I’ve even consulted Ray’s Principles of Planetary Climate textbook, which says Eq. 4.56 explains it — well, not for Dummies. Gavin and Eli seem to agree that Dr. Uherek does the best job of explaining it, and he certainly does so in few and simple words, but…?
Doug Bostromsays
David B. Benson says: 21 December 2009 at 3:19 PM
Yes indeed. I read somewhere that India alone may be making a significant contribution via groundwater, and of course that’s going to offset the impoundment deficit. I have a vague memory of somebody applying groundwater extraction against Chao’s results but dang if I can find it now…
Obviously the CRU robbery was timed to lead up to Copenhagen (why did they bother?). But I winder if it has been even more coordinated than that. It seems to me on every climate change thread on every site there has been a massive increase lately of denialist posters with new IDs flooding in with a consistent party line (even more consistent than usual). As well as the obligatory climategate conspiracy (leaked, of course, by an insider fed up with the lies), we have MWP (very big this month), climate has changed before, CERN cloud analysis (just you wait and see, all the climate scientists are going to feel raindrops falling on their heads), Greenland, and one world government. Al Gore, as always, is an obvious extra (in favour of one world government to make trillions of dollars from solar panels – who knew?). They drown out any other discussion, their madness and ignorance (nothing about climate change has ever been discussed before for these newbies) even more strident than it was just a few months ago. This looks to me like a ramped up astroturf operation, the starting gun fired as soon as the emails were leaked. Anyone else noticed the pattern?
Dan Lufkinsays
Perhaps someone has already posted this but MIT has put a video of a two-hour forum on “Climategate” on
It’s essentially Kerry Emanuel vs. Dick Lindzen. Worth watching.
Charly Cadousays
Gavin: Since no-one is allowed to ask whether the ‘science is settled’, that indicates to me that it is not. Therefore where is the rush to tackle AGW/climate change, are the politicians being fed cherry-picked info?
[Response: Please read the article I linked. -gavin]
James Staplessays
As I’ve mentioned before, I think we should be paying much more attention to the North Atlantic Conveyor – or, more precisely, the Deep Cold Return Flow; as this is the biggest potential ‘fly in the ointment’ for all of the ‘other’ theories and models out there.
Of course, since talking about the the effects of the shut-down of this conveyor could be misconstrued as an excuse to say that ‘AGW is fake science’ (it would plunge Northern Europe into a new Ice Age – but it would also warm the Southern Oceans so dramatically, that the Antarctic Ice Sheets would melt so quickly, that oure entire Coastal Infrastructure would soon be inundated), we need to point out that it’s no ‘solution’ to AGW.
John Masheysays
re: #216, “New rules”
It would be really nice if a top-level menu item were “Comment Policy”, and if one were posted, whatever it should be. I observe that some blogs have very good ones, and establishing the rules seems to help, such as at John Quiggin.
Three scientists have recently written a letter to The American Farm Bureau Federation, challenging their stated questioning of the influence of humans on climate change. The UCS is accepting signatures to the letter from PhDs or candidates with knowledge of climate science, at the first link above, but I encourage anyone without those credentials to write their own message to the AFB.
Modification of agricultural practices, especially in the United States, has the potential to make a very large impact on carbon emissions, through numerous pathways. These include especially, the effects of fertilization, pesticide application, and tillage practices on soil carbon storage and fossil fuel use. Current ag practices have other major impacts as well, particularly on the nitrogen cycle and its effect on far-removed aquatic ecosystems such as estuaries and deltas. The AFBF does not want farmers to have to change their land management practices in response to climate change concerns, and does not recognize the potential economic benefits in doing so if carbon is priced and management practices are altered in response.
I hope others will read the statement and the scientists’ response, and make their voices heard by the AFBF. Thanks.
Jim
Don Shorsays
“26 *So what’s the best response to the people who are saying loudly this morning that yesteday’s north-eastern record snow proves there is no such thing as global warming?*”
Try this:
There is no direct relationship between the steady increase in global temperature and your local, current weather. What matters is what is happening in the long run.
Bernhard Niederreitersays
It ist very interesting for me to see climate research getting out of the dark hole of conspiracy. Even by the mass of data it is unlikely, that a new discussion leads to an agreement between different parties. As selecting dataset supporting the own opinion is a method to rule results the power of media presence will decide the game.
Completely Fed Upsays
David #232 we also have the appearance of a new meme spreading “The Team”.
I don’t know why that’s supposed to be derogatory, mind, but I think it’s meant to be.
Completely Fed Upsays
“i think you should post a graph showing what the temperatures will look like for 2010. since you obviously have it all figured out”
What garry hasn’t figured out (and having failed to do so has proven his opening statement is incorrect) is that the temperature in 2010 is weather.
Not climate.
[Response: True, but it doesn’t mean there is no predictability. Starting off with an El Nino event definitely gives 2010 better than even odds of beating out 2009 for instance…. – gavin]
Completely Fed Upsays
“My thinking goes as follows:
Conservatives are resistant to anthropogenic global warming (AGW) because proposed corrective actions impose great costs with poor assurance they will be effective.”
Your thinking is begging the question: will the costs be great?
Stern report says we would be ~4 years late in reaching the same total GDP and we won’t see any significant collapse.
Given we already had ONE collapse caused by conservative dogma beating human intelligence/cynicism, and that WAS significant, why the scare over this?
James McDonaldsays
To my request for a terse, cogent description of the CRU controversy, Ray Ladbury replies “Because providing context for anything takes more time and space than taking it out of context and constructing a lie in which to embed it.”
That’s not a reasonable response. There ARE short explanations of the CRU controversy. I could generate a dozen in the next five minutes. What I don’t know is which are true and which are false. (Were the fudge factors in the code appropriate or not? Yes or No. What was that code used for? Everything published on the subject, a few major papers, a few technical reports, a teaching assignment, nothing, it never even compiled. Which is it? Was the “trick” to replace derived numbers with more direct measurements? Yes or no? Why Is is so damn hard to get definitive answers to a few concise questions? )
Everything I’ve seen indicates there are short, simple, and truthful replies to the skeptics, but no one is producing them.
So I repeat my request.
[Response: The ‘fudge factor’ calculation was an attempt to see if the calibration statistics were affected by the MXD post 1960-decline and were written up for publication but never actually published. It was a vaguely interesting calculation perhaps, but has no implication for anything else. The numbers themselves were calculated as a principle component of the divergence pattern. The “trick” was to get around the problem of wanting to produce a smoothed picture of the long term temperature trends when you have a discontinuity in the middle. Jones used a splice before smoothing in one figure in a WMO brochure 10 years ago that I had never seen prior to last month. Again, an issue of rather minor importance. We should however put up an FAQ on these kinds of things though to save time in the future. – gavin]
Disassembling and explaining the science and siginficance to climate modeling of this USGS study on Pliocene deep ocean circulation modeling would be a welcome post.
To make an honest comparison prof. MacKay should have calculated the number of nukes based that 125 kWh p.p.p.d. Can you show me where he does that?
“allege baselessly”? No sir.
It is complete nonsense to us a 125 kWh per person per day consumption stack as if the UK will ever need so much electricity.
You know, the book was featured on ‘The Register’ a few years back. You know what sound bite made it in the article? “We need to cover the whole of Whales in wind turbines to power half our cars.” I’ll leave the calculation of the real number as an exercise to you.
If Prof. MacKay likes renewables, he has a funny way of expressing it.
Anne van der Bomsays
Didactylus,
My memory faltered even more (must be getting old). It’s even worse. The consumption stack is a whopping 195 kWh pppd. Ten times the current British electricity consumption.
Lynn Vincentnathansays
RE #1 and “four in 10 Americans now saying that they place little or no trust in what scientists have to say about the environment”
This is sort of interesting, bec before RC, I didn’t have much trust in what scientists had to say about the environment, and that was based on how some have rigged the science to prove this or that chemical is not harm to humans….some scientists for the Formaledyde Institute even being sent to prison for falsifying their science. Read TOXIC DECEPTION for more. And then there is THE INSIDER and how industry scientists work. Also, some government scientists (esp state gov scientists) find it in their best interest to finnagle the science on toxic harms, etc. (there is diluting the experimental or treatment popultion with untreated people; and then doctoring the results, cherry-picking in and out data that do not fit the greed of the industry or government that is funding the science, etc).
So I may have been one of those people placing little or no confidence in what scientist have to say about the environment had not RC come along — I completely trust RC scientists, but I don’t know about others.
For instance, I place little or no confidence in what the climate skeptic scientists have to say.
So the question (from a scientific survey standard perspective) is really a bad question, obviously created unwittingly or wittingly by some media polling service, and we all know about the well-oiled media and how both sides of their bread are buttered by oil and toxins, etc. The question is another example of bad science that lowers people’s confidence in science.
Green For Peacesays
So, defending the “quality” of the science is obvious a perennial issue if not the raison d’etre for this blog. Gavin’s oft quoted range for sensitivity seems to be an IPCC-esque 1.5 .. 4.5 (or maybe 2..4.5, don’t let me misquote!).
The FAQ has material on this as well as reports, but a colleague of mine recently asked me why there has been so little “apparent progress” in reducing this range over the past 20 to 30 years in spite of many efforts.
Is this a) a misperception — the range has come down from a 6X spread to a 3X spread, b) (my impresseion) a basically correct perception but with various explanations.
Coincidentally, BPL seems to have just mentioned the Hubble constant discrepancies of cosmology’s past. IIRC that was mostly many things on one side and globular clusters on the other for several decades with globular clusters ultimately being the things considered misleading. The situation with climate sensitivity seems more subtle and complex than this, and I was not able to address it.
Perhaps there is simply a resource I don’t know about already here…
David B. Bensonsays
Nick Bone (218) — Hansen et al. wrote something similar to “350 ppm and likely less”. For lowest risk and highest climate stability, I propose close to 300 ppm CO2ewa (ewa: equiivalent with aerosols). But first we have to stop rising and start descending. That gives planty of time to determine the best value.
TRYsays
Ray, you suggest that Jim B. does not support his claims that organization support for AGW is comprised of strong support for weak claims or weak support for strong claims. You suggest he read the APS statement, which I include below in it’s entirety. Note that there is exactly one statement in support of AGW:
“If no mitigating actions are taken, significant disruptions in the Earth’s physical and ecological systems, social systems, security and human health are likely to occur.”
‘Likely’ is weak support. No timeline is weak support. Here’s what a strong statement would say: “We are highly confident that average global temperatures will rise 3 degrees over the next 100 years, causing x y and z, if mitigating action is not taken in the next 5 years.”
Yet they don’t say that, do they? And in fact, they are now reviewing it for changes to clarity and tone. I would guess that the support will be weaker and the claim will be weaker after this review.
Suggesting that this statement expresses strong support for any specific claim of temperature rise within any time period would seem to be pure rhetoric.
“Emissions of greenhouse gases from human activities are changing the atmosphere in ways that affect the Earth’s climate. Greenhouse gases include carbon dioxide as well as methane, nitrous oxide and other gases. They are emitted from fossil fuel combustion and a range of industrial and agricultural processes.
The evidence is incontrovertible: Global warming is occurring. If no mitigating actions are taken, significant disruptions in the Earth’s physical and ecological systems, social systems, security and human health are likely to occur. We must reduce emissions of greenhouse gases beginning now.
Because the complexity of the climate makes accurate prediction difficult, the APS urges an enhanced effort to understand the effects of human activity on the Earth’s climate, and to provide the technological options for meeting the climate challenge in the near and longer terms. The APS also urges governments, universities, national laboratories and its membership to support policies and actions that will reduce the emission of greenhouse gases.”
I have a question about stratospheric cooling. If the stratosphere is cooling because of both ozone loss and an enhanced tropospheric greenhouse effect, is there any way to assign proportional blame to these two factors? How much cooling is from ozone loss and how much is from more heat being trapped in lower layers of the atmosphere? Does the amount of cooling attributable to each factor vary with latitude and altitude? Is there a reliable source on the web for this information? Also, do the greenhouse properties of CFCs warm the stratosphere and offset any cooling from the loss of ozone?
I also really like the idea of RSS on inline comments.
Suggestion for a post:
‘Show The Code’
Let’s ask Svensmark and others to show their code and methods for verification.
I updated the Svensmark page with the Laschamp Event graphic for those interested:
http://www.ossfoundation.us/projects/environment/global-warming/myths/henrik-svensmark
Reply to #197:
Seconded!
#197 Brian Schmidt
If you block heat from escaping from the troposphere by adding GHG’s then the area above it would be cooler. sort of like living in a two story house and closing some heat vents that go up to the top floor. More heat downstairs, less heat upstairs.
Hope that helps.
[Response: No, this is not correct (think about what occurs at equilibrium where the net flux changes must be zero. The stratospheric cooling because of increasing CO2 is a function of the spectral nature of the absorption and the presence of other emitters in the lower atmosphere. – gavin]
#195 ghost
To get to papers:
http://scholar.google.com/
You are right, it would be a lot of work. I try on the OSS site to bring in together and ref. to source. That of course is also done in the RC posts.
@197: Brian Schmidt:
The last of these topics (if I understand your question) was covered in a recent RC post, and I will try to reproduce the gist of it here. The collisional rates between C02 and other molecules exceed the radiative rates of C02 by orders of magnitude, at least in the densest portions of the lower atmosphere, where local thermodynamic equilibrium is a good approximation. Typical collisions then result in de-excitation of the radiatively excited CO2 molecules, so that the collision is inelastic kinetic energy-wise. As the density drops with altitude, the collision rates drop off and radiative de-excitation becomes important. One of the experts can fill in the gaps.
26 *So what’s the best response to the people who are saying loudly this morning that yesteday’s north-eastern record snow proves there is no such thing as global warming?*
One might hazard the guess that
(A) increased global temperatures result in increased evaporation from the oceans aand more frequent precipitation events i.re. more snow or rain and more vioolent rainstorms and snowstorms. These would be more likely to occur over certain areas where air masses converge – especially the mid latitudes.
(B) Increased retention of energy of ultimately solar origin in the increasingly carbon rich atmosphere results in a high proportion of that energy being trtansferred to e.g. the Greenland ice cap where it causes melting and the storage of latent heat in the meltwaters. This means that from the polar regions there
will be increased probability of incursions of relatively cool air masses into lower latitudes, bringing chill weather and snowfall.
156 Spaceman Spiff: What I am saying, then, is that either way, we are toast. The climate can be sent into catastrophe by several mechanisms. I can’t give you a better answer.
Comment by Curmudgeon Cynic — 21 December 2009 @ 11:11 AM
Regarding ships displacing sea water, stimulation of oil fields, you might be interested in the role dam construction has played in the twentieth century.
Calculating the total volume of new impoundments filled during the past 100 years reveals a probable temporary masking of anthropogenic sea level increase, on the order of ~0.5mm/year, for a total effect of some 30mm.
Astounding, really, yet based on fairly reliable data.
Of course this is a -temporary- effect. As new dams are filled and the bulk of available sites are exploited, this effect will diminish.
http://www.sciencemag.org/cgi/content/abstract/320/5873/212?rss=1
Where can I get a year by year table of global temperatures for all the met offices that are collating such averages? All I can find are graphs with poor resolution. I’d like a resource on RC that collates and updates all the info every year.
Heat of Fusion: As a PhD organic chemist, my training exposed me to some thermodynamics and a modest understanding of the physics of water phase transitions. When I hear arguments skeptical of even the existence of global warming based on quibbles over global temperature data, my inclination is to insist that simple recognition of widespread ice melting alone is sufficient proof of a significant change in the earth’s heat balance. Further, I suspect the basic fact that the ice – water transition occurs with no change in temperature may well contribute to an explanation of why ocean temperatures can show limited change or even decrease locally during melting. Are these lines of reasoning sound from the perspective of knowledgeable climate scientists?
Peak Oil: This has more to do with politics and policy than with climate science, but I’m hoping to recruit supporters for my idea – or learn why I’m all wet. My thinking goes as follows:
Conservatives are resistant to anthropogenic global warming (AGW) because proposed corrective actions impose great costs with poor assurance they will be effective. The root of the resistance is uncertainty in the extent of climate impacts and uncertainty in our ability to prevent them. At the same time, we face a much more easily understood issue encapsulated by the term peak oil – the growing disparity between global crude oil production and world demand. I see it as being much easier for laymen and businessmen to grasp the economic impact of rapidly growing costs and sporadic shortfalls of petroleum products than it is to understand the dire projections of AGW. Businessmen especially can recognize the consequences of an annual growth rate of even as little as 1% in the difference between supply and demand and just about everyone today has memories of the gas lines and material allocations of the 70s and the effect of the recent speculative spike in oil price. The corrective actions that address peak oil – conservation, increased energy efficiency, reduction in petroleum dependence, alternative fuels, etc – are also a big component of any program to address AGW. So my point is if there’s an urgent need for action instead of fighting AGW deniers we’re better off focusing on convincing laymen and corporations alike of the need to take these actions in the name of peak oil, not AGW. The truth is a majority of the petroleum industry has already accepted the peak oil scenario. If, as Senator Inhofe claims, AGW turns out to be a sham then there’s no loss. If experience shows AGW is real, we’re already started on the program we need and we have justification to expand it.
This rationale is based partly on my impression that the timeframe for dire peak oil effects is shorter than that for AGW. I foresee peak oil economics within 10-20 years whereas I expect AGW impacts of comparable magnitude are farther out.
Rotten Ham,
My understanding is that stratospheric cooling due to ozone loss would be maximum around 20 km, while greenhouse-induced stratospheric cooling is predicted to be in the 40-50 km range. This is precisely what is observed. Here’s a pretty good summary:
http://skeptico.blogs.com/skeptico/2009/05/upper-stratosphere-cooling.html
hmmm… brain fuzz again. RC just did a post on ‘Show The Code’.
https://www.realclimate.org/index.php/archives/2009/12/please-show-us-your-code/
Are there others, other than Svensmark, that would fit well into this category? If so a list of those that should ‘show the code’ would be a follow up as it becomes appropriate.
Blair Dowden (#174) says: “Carbon dioxide levels have been much higher in the past, particularly during the Cretaceous. Yet there is a lot of evidence for Cretaceous coral reefs, and a lot of limestone and chalk deposits, as a visit to the south coast of England demonstrates. The explanation I have heard is that is because the rapid rate of carbon dioxide increase means the ocean does not have time to transfer the carbon dioxide to the deep ocean, so the surface gets acidified.”
Actually, as I understand it (and someone can correct me if I am wrong), the timescale issue is not so much associated with the transfer of CO2 to the deep ocean but is instead associated with the rate at which limestone can be leached from the land into the ocean where it can neutralize the acidification caused by the CO2. Also, this timescale issue works in the opposite way than you have proposed: When the change is slow enough, the ocean ends up not becoming more acidic because there is time for the neutralization processes to occur (as opposed to your point-of-view that when the change is slow enough, there is sufficient time for acidification to occur).
So, the Cretaceous did not have a strongly acidic ocean simply because there was enough time associated with the rise in CO2 levels that there was time for the limestone leaching to neutralize the increased acidity associated with a rise in CO2 in the oceans. At the PETM event, where there seems to have been a quite rapid increase in CO2 levels, there is evidence for significant acidification of the ocean. And, some combination of this acidification and the climate change (and maybe other effects?) caused a quite dramatic extinction event.
Blair, This looked like a pretty good treatment:
http://www.tos.org/oceanography/issues/issue_archive/issue_pdfs/20_2/20.2_caldeira.pdf
A couple of things to remember. Coral now is very different from what it was in the Cretaceous. Also, the carbon cycle then was a lot faster than it is now.
Rephrasing my question: do you think the science is settled? So what is the purpose of the CERN CLOUD experiment. Also notice that Svensmark is not that popular around this blog. Too bad, he seems like someone who thinks hard about the science.
[Response: New rules: #1. No-one is allowed to ask whether the ‘science is settled‘ because there are still papers published or experiments done. #2. Nobody gets credit for ‘appearing to think hard’ – when what matters is whether you think logically – irrespective of how hard that might be for you. – gavin]
Blair Dowden says:
21 December 2009 at 1:07 PM
I never questioned if global warming is happening, and in fact confirmed it in the next sentence. As for the Cretaceous issue, thanks for the suggestion, but somehow I doubt that thousands of organisms all simultaneously evolved a new method of fixing calcium carbonate. I am sure the answer, if known, is much more complex than that.
You might find some references here. You’ll see that in times of previous global greenhouse climate conditions sea water chemistry were times of calcite seas whereas to the present we are in the aragonite sea mode.
http://en.wikipedia.org/wiki/Calcite_sea
Gavin,
I’d like some discussion on your recent paper with Lunt, Haywood et al:
“Earth system sensitivity inferred from Pliocene modelling and data”. In particular, the high level conclusion that Earth system sensitivity is around 30-50% greater than Charney sensitivity.
A couple of questions arising from this:
1. How does this compare to Hansen et al’s estimate in “Target Atmospheric CO2 – Where Should Humanity Aim?”. Namely that Earth System Sensitivity is approximately double Charney (fast feedback) sensitivity, based on the Last Glacial Maximum. Why does the Plicoene estimate differ from this?
2. What does the Pliocene climate imply about Hansen’s 350 ppm target? My initial concern is that it would still be too high as a long-term stablilization target, because:
i) 350 ppm results in around 1 degree warming based on fast feedbacks,
so maybe 1.5-2 degrees of warming based on the slow feedbacks (admittedly over several centuries).
ii) The slow feedbacks would still imply a return to something like the Pliocene world with sea levels maybe 6-9 metres higher than today. In practice, that means sea levels continually rising by 1-2 meters per century for the next few centuries until the slow feedbacks are complete (and continual inundation of coastal cities, beaches, tidal zones etc. throughout that period).
Surely this constitues “dangerous” climate change?
3. Given the shambles in Copenhagen, what are the real long-term implications? What are the options for us getting back below 350ppm if we continue to overshoot massively into the middle of the 21st century? Should we be considering air capture, biochar or even more radical measures (foresting deserts, trying to dump alkili or limestone in the oceans etc)? Could we get right back to early industrial or pre-industrial levels, which is what we seem to need? What is the fastest we could reduce CO2 by such means, and do we have long enough?
Thanks,
Nick
re: Peak Oil
I suggest not going there, espe. In any case, Peak Coal (natural, or via regulation) is likely a lot more relevant. Perhaps, every once in a while, if there is a good paper that combines improved models of fossil fuel resources and climate, that might be worth a mention.
I would like to see a good scientific writeup of how and why tree rings respond in a linear fashion to temperature. I guess this must include a discussion of both density and width of early and late wood as well as the importance of the trees micro climate. The writeup should also describe how different species might respond differently as well as any caveats and limitations when using tree rings as a temperature proxy.
Hi, I have a quick question about the data used by CRU and GISS for their global temperature calculations. Do they largely use the same raw data? I’m aware of the differences re the arctic temperatures, are there other major differences in the way they calculate global temperatures?
I’d like to see more posts on the evidence that global warming and loss of artic sea ice may cause changes in Hadley Circulation Cells, atmospheric occillations, etc. See this article abstract as an example of perhaps unexpected climactic changes caused by AGW.
http://www.agu.org/pubs/crossref/2008/2008GL035607.shtml
Doug Bostrom (209) — That number needs to be offset by groundwater removal.
i think you should post a graph showing what the temperatures will look like for 2010. since you obviously have it all figured out and understand the earth’s weather system on a fundamental level, prove it. give monthly predictions with error bars and then track your score through the year. If your models are accurate then put them to the test. will 2010 be hotter than 2009?
@208 Edward Greisch:
Thanks for your reply. I certainly realize the toast part, but I was interested in the potential differences from an academic point of view. I suppose, as you indicate, we can use the catastrophic volcanic events to compare to what we’re trying to do…
For the benefit of the statistically-challenged among us, perhaps you could comment on:
http://www.foresight.org/nanodot/?p=3611
specifically, the graph at:
http://www.foresight.org/nanodot/wp-content/uploads/2009/12/cubic.png
Does this curvy line (making climate look like it’s going nowhere in particular) have some value compared to the linear trends we often see associated with climate data.
#204 Gavin, Thread
It’s going to be harder to devise an effective simple communication analogue for that.
I will review the troposphere posts again. If I can get it visualized properly in my head I can develop better analogues. I’m just not there yet. Absorption ad different frequencies in the spectrum are not something I have assimilated well, yet.
I reviewed http://www.atmosphere.mpg.de/enid/20c.html (Thanks Ray)
Can cooling due to ozone still be illustrated by saying the stratospheric vents are left open to the troposphere allowing more IR to penetrate downward and not agitate as much in the stratosphere?
But it still seems though that the greenhouse effect can be described in part by closing some upward vents? Maybe each blocked frequency needs to be considered a different vent for my analogue?
In my mind, this raises a question. Has the mean altitude of a relative equilibrium state changed? Then has it become lower and by how much? I apologize as I’m still unsure what I am asking and trying to get a better picture in my head.
If the stratosphere emits radiates more heat into space, then maybe the picture is a roof with more holes than the floor below being more solid (troposphere)?
It also looks like there are two different floors, the ozone floor and the Co2 floor. So maybe for my analogue I need two houses?
Any help here would be appreciated :) I have been wanting to update my troposphere page for a while, but I don’t have enough confidence yet.
> gary thompson says: 21 December 2009 at 3:0 PM
Ya know what I wish you’d provide here, Gavin?
http://userscripts.org/scripts/show/4107
Another request for the New Year, inspired by the mysterious spectral nature of Gavin’s inline #204:
The Ultimate How and Why of CO2-induced Stratospheric Cooling for Dummies (that is, With Very Little Math)
OK, I understand why you might prefer to gnaw off your leg than have another go at this. I have checked out Gavin’s attempts here as well as Stoat’s, Eli’s, and Dr. Uherek’s ESPERE page, all somewhat different. I’ve even consulted Ray’s Principles of Planetary Climate textbook, which says Eq. 4.56 explains it — well, not for Dummies. Gavin and Eli seem to agree that Dr. Uherek does the best job of explaining it, and he certainly does so in few and simple words, but…?
David B. Benson says: 21 December 2009 at 3:19 PM
Yes indeed. I read somewhere that India alone may be making a significant contribution via groundwater, and of course that’s going to offset the impoundment deficit. I have a vague memory of somebody applying groundwater extraction against Chao’s results but dang if I can find it now…
I thought I would share some humor regarding CLimateGate
http://www.huffingtonpost.com/2009/12/08/fox-news-fuzzy-math-claim_n_384308.html
Obviously the CRU robbery was timed to lead up to Copenhagen (why did they bother?). But I winder if it has been even more coordinated than that. It seems to me on every climate change thread on every site there has been a massive increase lately of denialist posters with new IDs flooding in with a consistent party line (even more consistent than usual). As well as the obligatory climategate conspiracy (leaked, of course, by an insider fed up with the lies), we have MWP (very big this month), climate has changed before, CERN cloud analysis (just you wait and see, all the climate scientists are going to feel raindrops falling on their heads), Greenland, and one world government. Al Gore, as always, is an obvious extra (in favour of one world government to make trillions of dollars from solar panels – who knew?). They drown out any other discussion, their madness and ignorance (nothing about climate change has ever been discussed before for these newbies) even more strident than it was just a few months ago. This looks to me like a ramped up astroturf operation, the starting gun fired as soon as the emails were leaked. Anyone else noticed the pattern?
Perhaps someone has already posted this but MIT has put a video of a two-hour forum on “Climategate” on
http://mitworld.mit.edu/video/730
It’s essentially Kerry Emanuel vs. Dick Lindzen. Worth watching.
Gavin: Since no-one is allowed to ask whether the ‘science is settled’, that indicates to me that it is not. Therefore where is the rush to tackle AGW/climate change, are the politicians being fed cherry-picked info?
[Response: Please read the article I linked. -gavin]
As I’ve mentioned before, I think we should be paying much more attention to the North Atlantic Conveyor – or, more precisely, the Deep Cold Return Flow; as this is the biggest potential ‘fly in the ointment’ for all of the ‘other’ theories and models out there.
Of course, since talking about the the effects of the shut-down of this conveyor could be misconstrued as an excuse to say that ‘AGW is fake science’ (it would plunge Northern Europe into a new Ice Age – but it would also warm the Southern Oceans so dramatically, that the Antarctic Ice Sheets would melt so quickly, that oure entire Coastal Infrastructure would soon be inundated), we need to point out that it’s no ‘solution’ to AGW.
re: #216, “New rules”
It would be really nice if a top-level menu item were “Comment Policy”, and if one were posted, whatever it should be. I observe that some blogs have very good ones, and establishing the rules seems to help, such as at John Quiggin.
Open letter to American Farm Bureau Federation:
Three scientists have recently written a letter to The American Farm Bureau Federation, challenging their stated questioning of the influence of humans on climate change. The UCS is accepting signatures to the letter from PhDs or candidates with knowledge of climate science, at the first link above, but I encourage anyone without those credentials to write their own message to the AFB.
Modification of agricultural practices, especially in the United States, has the potential to make a very large impact on carbon emissions, through numerous pathways. These include especially, the effects of fertilization, pesticide application, and tillage practices on soil carbon storage and fossil fuel use. Current ag practices have other major impacts as well, particularly on the nitrogen cycle and its effect on far-removed aquatic ecosystems such as estuaries and deltas. The AFBF does not want farmers to have to change their land management practices in response to climate change concerns, and does not recognize the potential economic benefits in doing so if carbon is priced and management practices are altered in response.
I hope others will read the statement and the scientists’ response, and make their voices heard by the AFBF. Thanks.
Jim
“26 *So what’s the best response to the people who are saying loudly this morning that yesteday’s north-eastern record snow proves there is no such thing as global warming?*”
Try this:
There is no direct relationship between the steady increase in global temperature and your local, current weather. What matters is what is happening in the long run.
It ist very interesting for me to see climate research getting out of the dark hole of conspiracy. Even by the mass of data it is unlikely, that a new discussion leads to an agreement between different parties. As selecting dataset supporting the own opinion is a method to rule results the power of media presence will decide the game.
David #232 we also have the appearance of a new meme spreading “The Team”.
I don’t know why that’s supposed to be derogatory, mind, but I think it’s meant to be.
“i think you should post a graph showing what the temperatures will look like for 2010. since you obviously have it all figured out”
What garry hasn’t figured out (and having failed to do so has proven his opening statement is incorrect) is that the temperature in 2010 is weather.
Not climate.
[Response: True, but it doesn’t mean there is no predictability. Starting off with an El Nino event definitely gives 2010 better than even odds of beating out 2009 for instance…. – gavin]
“My thinking goes as follows:
Conservatives are resistant to anthropogenic global warming (AGW) because proposed corrective actions impose great costs with poor assurance they will be effective.”
Your thinking is begging the question: will the costs be great?
Stern report says we would be ~4 years late in reaching the same total GDP and we won’t see any significant collapse.
Given we already had ONE collapse caused by conservative dogma beating human intelligence/cynicism, and that WAS significant, why the scare over this?
To my request for a terse, cogent description of the CRU controversy, Ray Ladbury replies “Because providing context for anything takes more time and space than taking it out of context and constructing a lie in which to embed it.”
That’s not a reasonable response. There ARE short explanations of the CRU controversy. I could generate a dozen in the next five minutes. What I don’t know is which are true and which are false. (Were the fudge factors in the code appropriate or not? Yes or No. What was that code used for? Everything published on the subject, a few major papers, a few technical reports, a teaching assignment, nothing, it never even compiled. Which is it? Was the “trick” to replace derived numbers with more direct measurements? Yes or no? Why Is is so damn hard to get definitive answers to a few concise questions? )
Everything I’ve seen indicates there are short, simple, and truthful replies to the skeptics, but no one is producing them.
So I repeat my request.
[Response: The ‘fudge factor’ calculation was an attempt to see if the calibration statistics were affected by the MXD post 1960-decline and were written up for publication but never actually published. It was a vaguely interesting calculation perhaps, but has no implication for anything else. The numbers themselves were calculated as a principle component of the divergence pattern. The “trick” was to get around the problem of wanting to produce a smoothed picture of the long term temperature trends when you have a discontinuity in the middle. Jones used a splice before smoothing in one figure in a WMO brochure 10 years ago that I had never seen prior to last month. Again, an issue of rather minor importance. We should however put up an FAQ on these kinds of things though to save time in the future. – gavin]
http://www.usgs.gov/newsroom/article.asp?ID=2363
Disassembling and explaining the science and siginficance to climate modeling of this USGS study on Pliocene deep ocean circulation modeling would be a welcome post.
Didactylus #192
The 125 kWh benchmark for renewables is on page 103: http://www.inference.phy.cam.ac.uk/withouthotair/c24/page_166.shtml
The calculation on land use for Britain with nuclear power is on page 166-167: http://www.inference.phy.cam.ac.uk/withouthotair/c24/page_166.shtml. You will see he uses a number of 22 kWh per person per day (the 18 I remembered incorrectly).
To make an honest comparison prof. MacKay should have calculated the number of nukes based that 125 kWh p.p.p.d. Can you show me where he does that?
“allege baselessly”? No sir.
It is complete nonsense to us a 125 kWh per person per day consumption stack as if the UK will ever need so much electricity.
You know, the book was featured on ‘The Register’ a few years back. You know what sound bite made it in the article? “We need to cover the whole of Whales in wind turbines to power half our cars.” I’ll leave the calculation of the real number as an exercise to you.
If Prof. MacKay likes renewables, he has a funny way of expressing it.
Didactylus,
My memory faltered even more (must be getting old). It’s even worse. The consumption stack is a whopping 195 kWh pppd. Ten times the current British electricity consumption.
RE #1 and “four in 10 Americans now saying that they place little or no trust in what scientists have to say about the environment”
This is sort of interesting, bec before RC, I didn’t have much trust in what scientists had to say about the environment, and that was based on how some have rigged the science to prove this or that chemical is not harm to humans….some scientists for the Formaledyde Institute even being sent to prison for falsifying their science. Read TOXIC DECEPTION for more. And then there is THE INSIDER and how industry scientists work. Also, some government scientists (esp state gov scientists) find it in their best interest to finnagle the science on toxic harms, etc. (there is diluting the experimental or treatment popultion with untreated people; and then doctoring the results, cherry-picking in and out data that do not fit the greed of the industry or government that is funding the science, etc).
So I may have been one of those people placing little or no confidence in what scientist have to say about the environment had not RC come along — I completely trust RC scientists, but I don’t know about others.
For instance, I place little or no confidence in what the climate skeptic scientists have to say.
So the question (from a scientific survey standard perspective) is really a bad question, obviously created unwittingly or wittingly by some media polling service, and we all know about the well-oiled media and how both sides of their bread are buttered by oil and toxins, etc. The question is another example of bad science that lowers people’s confidence in science.
So, defending the “quality” of the science is obvious a perennial issue if not the raison d’etre for this blog. Gavin’s oft quoted range for sensitivity seems to be an IPCC-esque 1.5 .. 4.5 (or maybe 2..4.5, don’t let me misquote!).
The FAQ has material on this as well as reports, but a colleague of mine recently asked me why there has been so little “apparent progress” in reducing this range over the past 20 to 30 years in spite of many efforts.
Is this a) a misperception — the range has come down from a 6X spread to a 3X spread, b) (my impresseion) a basically correct perception but with various explanations.
Coincidentally, BPL seems to have just mentioned the Hubble constant discrepancies of cosmology’s past. IIRC that was mostly many things on one side and globular clusters on the other for several decades with globular clusters ultimately being the things considered misleading. The situation with climate sensitivity seems more subtle and complex than this, and I was not able to address it.
Perhaps there is simply a resource I don’t know about already here…
Nick Bone (218) — Hansen et al. wrote something similar to “350 ppm and likely less”. For lowest risk and highest climate stability, I propose close to 300 ppm CO2ewa (ewa: equiivalent with aerosols). But first we have to stop rising and start descending. That gives planty of time to determine the best value.
Ray, you suggest that Jim B. does not support his claims that organization support for AGW is comprised of strong support for weak claims or weak support for strong claims. You suggest he read the APS statement, which I include below in it’s entirety. Note that there is exactly one statement in support of AGW:
“If no mitigating actions are taken, significant disruptions in the Earth’s physical and ecological systems, social systems, security and human health are likely to occur.”
‘Likely’ is weak support. No timeline is weak support. Here’s what a strong statement would say: “We are highly confident that average global temperatures will rise 3 degrees over the next 100 years, causing x y and z, if mitigating action is not taken in the next 5 years.”
Yet they don’t say that, do they? And in fact, they are now reviewing it for changes to clarity and tone. I would guess that the support will be weaker and the claim will be weaker after this review.
Suggesting that this statement expresses strong support for any specific claim of temperature rise within any time period would seem to be pure rhetoric.
“Emissions of greenhouse gases from human activities are changing the atmosphere in ways that affect the Earth’s climate. Greenhouse gases include carbon dioxide as well as methane, nitrous oxide and other gases. They are emitted from fossil fuel combustion and a range of industrial and agricultural processes.
The evidence is incontrovertible: Global warming is occurring. If no mitigating actions are taken, significant disruptions in the Earth’s physical and ecological systems, social systems, security and human health are likely to occur. We must reduce emissions of greenhouse gases beginning now.
Because the complexity of the climate makes accurate prediction difficult, the APS urges an enhanced effort to understand the effects of human activity on the Earth’s climate, and to provide the technological options for meeting the climate challenge in the near and longer terms. The APS also urges governments, universities, national laboratories and its membership to support policies and actions that will reduce the emission of greenhouse gases.”