Saturday, March 20, 2010

RealClimate: Saleska Responds (green is green)

March 20th, 2010
In a recent post here at RealClimate, Simon Lewis wrote regarding a 2010 paper by Samanta et al. on the effect of single-year drought conditions on the Amazon. Samanta et al. claimed to have contradicted a 2007 paper by Scott Saleska et al., and to have thereby overturned some IPCC conclusions.

Lewis showed why Samanta’s paper did not contradict the IPCC, even if it may have correctly identified an error in Saleska et al. Now Saleska has written to say that, actually, Samanta et al.’s results do not identify any error in their work: the results agree completely. With our apologies for the journalistic whiplash, Simon Lewis and I are convinced he’s right. The more general point though, is that the the balance of evidence shows that the Amazon is sensitive to drought, and the IPCC’s statements about it remain valid.
Here is Saleska’s commentary in full
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Friday, March 19, 2010

RealClimate: Up is Down, Brown is Green (with apologies to Orwell)

March 15th, 2010
In the alternate universe of Fox News, Anthony Watts, and many others, up is down. Now, it appears, brown is green. Following the total confusion over the retraction of a paper on sea level, claims of another “mistake” by the IPCC are making the rounds of the blogosphere. This time, the issue is the impact of rainfall changes on the Amazon rainforest.

A study in 2007 showed that the forest gets greener when it rains less. A new study, by Samanta et al. in Geophysical Research Letters shows that the earlier work was flawed. Aided by an apparently rather careless press release, this is being used as evidence that the Amazon is less sensitive to rainfall changes than the IPCC claimed. But the Samanta et al. paper actually does not address the central questions at all. It only addresses whether a single anomalous rainfall year had an impact that is measureable and interpretable from a satellite sensor. The conclusion is that they could not detect a change. As noted in a commentary from Simon Lewis, University of Leeds, “the critical question is how these forests respond to repeated droughts, not merely single-year droughts.”

Lewis – a broadly published expert on tropical forests – makes a number of additional important points in his commentary below. Bottom line: IPCC gets it right as usual.
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Open Mind: Still Not

March 16th, 2010
Those who can’t bear to believe that the laws of physics govern global temperature, still want to maintain that it’s a random walk. They base this on the fact that the ADF (Augmented Dickey-Fuller test) doesn’t reject the presence of a unit root, if you refuse to use the BIC (Bayesian Information Criterion) for model selection and you’re willing to ignore the Phillips-Perron unit root test.
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Sunday, March 7, 2010

RealClimate: A mistaken message from IoP?

March 6th, 2010
The Institute of Physics (IoP) recently made a splash in the media through a statement about the implications of the e-mails stolen in the CRU hack. A couple of articles in the Guardian report how this statement was submitted to an inquiry into the CRU hack and provide some background.

The statement calls for increased transparency, and expresses concerns about the public confidence in science if the transparency is absent. The IoP statement, however, fails to note that the issue of transparency is far more general applicable than just to mainstream climate science. It should also involve the critics of climate change, as noted by New Scientist.
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RealClimate: Arctic Methane on the Move?

March 6th, 2010
Methane is like the radical wing of the carbon cycle, in today’s atmosphere a stronger greenhouse gas per molecule than CO2, and an atmospheric concentration that can change more quickly than CO2 can. There has been a lot of press coverage of a new paper in Science this week called “Extensive methane venting to the atmosphere from sediments of the East Siberian Arctic Shelf”, which comes on the heels of a handful of interrelated methane papers in the last year or so. Is now the time to get frightened?
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Friday, March 5, 2010

Open Mind: Message to Anthony Watts

March 5th, 2010
Anthony:

It has now been independenly confirmed, by multiple persons, that my results regarding the impact of station dropout on global temperature are correct. Your claims, in your document with Joe D’Aleo for the SPPI, are just plain wrong.
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Open Mind: Global Update

March 5th, 2010
I’ve finished processing the southern hemisphere GHCN data, and computed the temperature according to the simple procedure for the entire globe.
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