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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Are they trying to hide the overestimated rise promoted by their climate models?
What about anthropogenic carbon dioxide has ZERO impact on climate?
Rut Ro!
Of course, this can simply be trashed like the Soon / Baliunas 2003 paper was. After all, it doesn’t agree with the reality of the world as expressed in the models.
Maybe it is already clear to others, but how much of a reduction in the amplification does this indicate? Or to put it another way, based on this report, by what percentage have the IPCC-Gore-Hansen crowd been overstating the effect of warming due to CO2?
Well of course it is. The weather/climate is not cooperating and not agreeing with their models.
Just like Menne had to rush a paper out trying to disprove Watts/Pielke Sr, first, before Watts/Pielke Sr could get theirs out.
They are just CYA.
Now they can still say “see we were right”.
Not quite an order of magnitude. Close as in horse shoes. This should have been in the state of the union message “crisis over we have solved the problem through bipartisan support and effort….” Shortly Mz Jackson will refund some of her EPA budget increase in sympathy with the job loss due to her threats oops findings.
@RAYQ MCMULLEN (12:27:35)
The BBC article is more detailed: http://news.bbc.co.uk/2/hi/science/nature/8483722.stm
“for every degree Celsius of warming, natural ecosystems tend to release an extra 7.7 parts per million of CO2 to the atmosphere (the full range of their estimate was between 1.7 and 21.4 parts per million).
This stands in sharp contrast to the recent estimates of positive feedback models, which suggest a release of 40 parts per million per degree; the team say with 95% certainty that value is an overestimate.
“
So for o.8 degrees C warming in the last 100 years we would have about 6 ppm increase in CO2 using their mid range estimate. I did a crude stab at such an estimate using ice core data a couple of years ago and estimated <10 ppm of the increase we have seen was due to warming. Seems reasonable, and hardly a cause for concern.
The science is “settled” … like solids in a cesspool
Henry’s law already describes the relationship between water temp and CO2 in the atmosphere. This is just a way to claim humans are responsible for the CO2 increase rather than the fact that 95% of the increase is due natural ocean warming. For every 50 molecules of CO2 we produce, only one will remain in the atmosphere at equilibrium, which takes about ten years based on CO2 ocean atmosphere exchange.
Bah ha ha ha ha ha ha ha ha ha ha ha ha ha. Oh…my sides! bah hah haha.
Since the response to CO2 is a log function it implies that the positive feedback effect will decline with increasing concentrations. And in any case it is a minor factor compared to water vapor.
Lubos is discussing and clarifying the paper at his site:
http://motls.blogspot.com/2010/01/nature-carbon-cycle-feedback-is-80.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.
Two points emerge from this:
Firstly, Hans Erren’s “quick and dirty” method using vostock ice core data produced an estimate ~10 ppm per deg C. Not bad for a 30 second calculation. See here:
http://members.multimania.nl/ErrenWijlens/co2/howmuch.htm
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.
This means overstated temp estimates of about a third, according to one skeptic physicist:
http://motls.blogspot.com/2010/01/nature-carbon-cycle-feedback-is-80.html
One major issue that I see is that the researchers are using proxy records to do their estimations. Skeptics cannot have it both ways. Either the proxy records are problematic or they are not.
The only safe conclusion is that some people are way too certain about climate sensitivity.
According to IPCC figure 9.9, anthropogenic contribution to temperature rise is about 90% in the seconde half of the XXth century, with CO2 being the main forcing agent.
How would this paper change the anthropgenic/natural contribution to temperature rise ?
Thx
They have been overstating by between 89% and 235%.
One is tempted to paraphrase:
The science was right before, the earlier numbers misbehaved. “Bad. bad, numbers. Depart from us. Hence forth we will use different numbers.”
More seriously. It sounds like careful work. I hope it holds up.
The geologic record shows no correlation between CO2 and temperature.
http://ff.org/centers/csspp/library/co2weekly/2005-08-18/dioxide_files/image002.gif
There was an ice age in the late Ordovician with CO2 levels 10X of current levels. Hansen et al are not interested in looking at geological timescales though, because it would nullify their raison d’etre.
I have my doubts about this. Still haven’t had a chance to read through the whole paper, but the list of temperature reconstructions used should raise a few eyebrows:
Jones199831 (blue 3), Briffa200032 (blue 2), MannJones200333 (blue 1), Moberg200534 (light blue), DArrigo200635 (green), Hegerl200736 (yellow), Frank200737 (orange), Juckes200738 (red), Mann200839 (maroon)
There’s a fine collection of hockey sticks.
The German Der Spiegel had a story on this yesterday. They did admit, that the feedback effect would be smaller than previously thought, but:
There would be absolutely no reason to take back any previous warning, because:
-human CO2 emissions would rise rapidly, anyway
-the scientists could not simulate feedbacks which occur at larger temperature variations than we have seen the last 1000 years (e.g. because of the evil methane there could be unprevedented feedbacks)
Furthermore other researchs would suggest that climate change would have been underestimeted so far (sic!), e.g. 5 Million years ago it was warmer than today, with CO2levels only slightly higher.
The conclusion of the article was: Possibly an atmospheric CO2 concentration of 400-500 ppm is enough for a runaway warming…
So still, even if climate feedback is lesss than we feared, it is still worth than we thought. Yes, repeat no…
I’m a little confused about this AGW theory.
From what I think they’re tell us, regardless of amplification:
If the earth warms as a result of increased atmospheric CO2
that warming results in a warmer ocean
warmer oceans hold less CO2, thus expelling it to raise atmospheric CO2
hence CO2 and temperature go up forever.
According to the commonly discussed theory, why wouldn’t this continue to runaway?
MikeEE
At least they got the general flow right. If you increase temperature….. you increase as co2 as it comes out of solution from the ocean
“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.”
Probably so, but absent the warming fear we can strip CO2 of all of it’s undeserved bad press and accept it for it’s pro-botanical effects on the planet.
There is a more complete explanation of the article by the BBC:
http://news.bbc.co.uk/2/hi/science/nature/8483722.stm
“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.”
“…”It might lead to a downward mean revision of those (climate) models which already include the carbon cycle, but an upward revision in those which do not include the carbon cycle.
“That’ll probably even itself out to signify no real change in the temperature projections overall,” he said. “