Amplification of Global Warming by Carbon-Cycle Feedback Significantly Less Than Thought, Study Suggests
from ScienceDaily (Jan. 28, 2010) — A new estimate of the feedback between temperature and atmospheric carbon dioxide (CO2) concentration has been derived from a comprehensive comparison of temperature and CO2 records spanning the past millennium.
The result, which is based on more than 200,000 individual comparisons, implies that the amplification of current global warming by carbon-cycle feedback will be significantly less than recent work has suggested.
Climate warming causes many changes in the global carbon cycle, with the net effect generally considered to be an increase in atmospheric CO2 with increasing temperature — in other words, a positive feedback between temperature and CO2. Uncertainty in the magnitude of this feedback has led to a wide range in projections of current global warming: about 40% of the uncertainty in these projections comes from this source.
Recent attempts to quantify the feedback by examining the co-variation of pre-industrial climate and CO2 records yielded estimates of about 40 parts per million by volume (p.p.m.v.) CO2 per degree Celsius, which would imply significant amplification of current warming trends.
In this week’s Nature, David Frank and colleagues extend this empirical approach by comparing nine global-scale temperature reconstructions with CO2 data from three Antarctic ice cores over the period ad 1050-1800. The authors derive a likely range for the feedback strength of 1.7-21.4 p.p.m.v. CO2 per degree Celsius, with a median value of 7.7.
The researchers conclude that the recent estimates of 40 p.p.m.v. CO2 per degree Celsius can be excluded with 95% confidence, suggesting significantly less amplification of current warming.
Journal Reference:
- David C. Frank, Jan Esper, Christoph C. Raible, Ulf Büntgen, Valerie Trouet, Benjamin Stocker, & Fortunat Joos. Ensemble reconstruction constraints on the global carbon cycle sensitivity to climate. Nature, 2010; 463 (7280): 527 DOI: 10.1038/nature08769
Full story here at Science Daily
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Then there’s this insanity. The public just doesn’t ‘get’ it. Cold is warm. Up is down.
http://www.msnbc.msn.com/id/35118098/ns/us_news-washington_post/
Mark this one on the calendar! Instead of “worse than we thought,” as is usually the case, it says “less than we thought.” I’m going out now to see if there are any pigs flying around.
Excuse me if this is a dumb question, but what does this say about climate sensitivity to a doubling of CO2?
And does it have anything to do with carbon sinks (oceans, fauna) becoming saturated?
Am I right in I thinking that from a warmist point of view this is good news, meaning there is more time to transition to a sustainable society?
I am amazed at how in the picture the tropics (especially South America) absorb so much CO2 that they leave a visible trail of lower CO2. Does this mean that as the higher concentration in the northern hemisphere mixes and some travels to the southern hemisphere, that it all gets absorbed? Has this Amazon rate been studied?
And yet another peer-reviewed paper that debunks the alarmist tongue wagging that skeptics have no science to back their arguments.
The issue of feedbacks will make or break AGW.
The BBC article seems to answer most of my questions. I think that for the sake of objectivity and impartiality it might be a good thing to add these lines to this blog entry:
“The authors warn, though, that their research will not reduce projections of future temperature rises.
Further, they say their concern about man-made climate change remains high.
The research, from a team of scientists in Switzerland and Germany, attempts to settle one of the great debates in climate science about exactly how the Earth’s natural carbon cycle will exacerbate any man-made warming.
Positive, negative
Some climate sceptics have argued that a warmer world will increase the land available for vegetation, which will in turn absorb CO2 and temper further warming. This is known as a negative feedback loop – the Earth acting to keep itself in balance.
But the Nature research concludes that any negative feedback will be swamped by positive feedback in which extra CO2 is released from the oceans and from already-forested areas.
The oceans are the world’s great store of CO2, but the warmer they become, the less CO2 they can absorb. And forests dried out by increased temperatures tend to decay and release CO2 from their trees and soils. ”
Source: BBC
I was starting to get excited, and then I saw “nine global-scale temperature reconstructions” and said to myself “uh oh”.
So. . .which nine GSTR did they use, and do any of them have the MWP at anything like a likely scale? And if they don’t, what happens to their results if a real MWP is included?
I also wasn’t real clear (I think not, but I’m not sure) if this was a different issue that they were looking at than the positive wator vapor feedback thing? Same issue or different one?
It seems that 40 (modelled) divided by 7.7 (probable) = a 5.2 fold modelling claim beyond the empirical values.
Projecting 2.0 deg by 2100 / 5.2 = 0.4 which is close to a number of other opinions. The point about non-linear response above is noted. Perhaps 0.3 then, with a natural background variation of 3-4 (my opinion).
Regards
Nature supported the idea of positive feedback before they didn’t.
It’s nice that Nature is showing a willingness to publish some slightly contrarian info, but since the authors used Antarctic ice cores for CO2 which seem to be more than a bit problematic and compared them to paleoclimate reconstructions, which I’m unwilling to invest $32 to identify but in general I’ve never found to be confidence inspiring, I doubt I’ll be adding this to my reference file.
Soller (12:35:17) :
I was not talking about total CO2 but only ANTHROPOGENIC CO2… The anthropogenic part of the total CO2 is insignificant and will insignificantly contribute to any positive OR negative feedback. In other words: We have zero impact on global temperature change, 0. Of course, I am saying 0 with only 1 significant figure… I too have some uncertainly.
The authors claim that based on Antarctic ice cores, increasing temperatures release less CO2 than previously thought. In other words, increasing temperatures cause CO2 concentration increases, not the reverse. It seems rather twisted logic to claim feedbacks based on such data.
I can hear Gavin Schmidt cursing now. This is another paper where he will have to find some way to trash it on RealClimate.
I wondering how they’re going to spin that one. I’m sure they’ll think of something. OT, but Fox is running yet another story re: the IPCC’s incompetence. I think we finally got them monitoring this site. http://www.foxnews.com/scitech/2010/01/28/save-rainforest-climate-change-scandal-chopped-facts/
This paper adds further support to what the chemical engineers have known all along: CO2 can have no influence on average earth temperature due to process control fundamentals. I’ve placed this link here before, but this seems like a good time to post it again. Perhaps in a few more iterations and/or papers published, the scientists will agree with the engineers.
http://sowellslawblog.blogspot.com/2009/02/chemical-engineer-takes-on-global.html
“The authors derive a likely range for the feedback strength of 1.7-21.4 p.p.m.v. CO2 per degree Celsius, with a median value of 7.7”
Talk about impressive pinpoint accuracy.
Is that like forcasting warming to be represented by anomalies of the same magnitude?
With that wide fat range, they can’t be proven wrong.
Am I correct in assuming that “co-variation” is the same as amplification?
If that be correct then a co-variation of 7.7 is over 500% less than the co-variation of 40, which can be excluded with 95% confidence.
What about “co-variation” factors that lead to negative amplification / acceleration, such as those that come into play when temperatures are falling while CO2 is rising as during the start of an ice-age, or in the last decade?
Oh look, they got the stratosphere and water vapor wrong too…
http://www.nature.com/news/2010/100128/full/news.2010.42.html
Now the big boys are moving in doing the real science.
John Finn (12:43:31) :
Secondly, this surely settles any debate about mankind’s involvement in the increase in 20th century CO2 concentrations. The CO2 increase cannot be due to higher temperatures.
1) The temperature rise is a lot less than slated.
2)1940’s co2 levels were measured to be higher than 1975’s co2 levels.
Neven:
“The authors warn, though, that their research will not reduce projections of future temperature rises.”
Neven, these people have to appear to be agreeing with the AGW narrative even while they are disagreeing with it. In many cases their research grants depend on it. The important thing is that the climate sensitivity number keeps getting walked down, little by little.
There is no p.p.m.v. CO2 per C degrees of temperature. Nature doesn’t work in such a linear way. If you could make such linear predictions, or any predictions, about a chaotic non-linear system then we’d do the same with the stock market like so many charlatans try to convince people they can do.
“Its less than we thought”
and accelerating?
Is this paper saying that since warming itself is not the cause of as much of the observed C02 buildup as previously thought then the measured increase of atmospheric C02 must be coming more from anthropogenic sources? In other words, it’s worse than we thought!
I presume that these 1000 year old “atmospheric” CO2 levels come from gas bubbles in Antarctic ice cores? CO2 is very soluble in water and diffuses very quickly through aqueous solutions. I find it very difficult to believe it hasn’t equilibrated to a very large extent with the air and must, therefore be a very poor reflection of the CO2 level at the time the bubble formed.
Someone please tell me I’m wrong.