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Daily Mangle

Classé dans: — group @ 15 février 2010

Yesterday, the Daily Mail of the UK published a predictably inaccurate article entitled “Climategate U-turn as scientist at centre of row admits: There has been no global warming since 1995″.

The title itself is a distortion of what Jones actually said in an interview with the BBC. What Jones actually said is that, while the globe has nominally warmed since 1995, it is difficult to establish the statistical significance of that warming given the short nature of the time interval (1995-present) involved. The warming trend consequently doesn’t quite achieve statistical significance. But it is extremely difficult to establish a statistically significant trend over a time interval as short as 15 years–a point we have made countless times at RealClimate. It is also worth noting that the CRU record indicates slightly less warming than other global temperature estimates such as the GISS record.

The article also incorrectly equates instrumental surface temperature data that Jones and CRU have assembled to estimate the modern surface temperature trends with paleoclimate data used to estimate temperatures in past centuries, falsely asserting that the former “has been used to produce the ‘hockey stick graph’”.

Finally, the article intentionally distorts comments that Jones made about the so-called “Medieval Warm Period”. Jones stated in his BBC interview that “There is much debate over whether the Medieval Warm Period was global in extent or not. The MWP is most clearly expressed in parts of North America, the North Atlantic and Europe and parts of Asia” and that “For it to be global in extent, the MWP would need to be seen clearly in more records from the tropical regions and the Southern hemisphere. There are very few palaeoclimatic records for these latter two regions.”

These are statements with which we entirely agree, and they are moreover fully consistent with the conclusions of the most recent IPCC report, and the numerous peer-reviewed publications on this issue since. Those conclusions are that recent Northern Hemisphere warming is likely unprecedented in at least a millennium (at least 1300 years, in fact), and that evidence in the Southern Hemisphere is currently too sparse for confident conclusions. Mann et al in fact drew those same conclusions in their most recent work on this problem (PNAS, 2008).

Unfortunately, these kinds of distortions are all too common in the press nowadays and so we must all be prepared to respond to those journalists and editors who confuse the public with such inaccuracies.

Update 2/16/10. Phil Jones has confirmed to us that our interpretations of his comments in the BBC interview are indeed the correct ones, and that he agrees with the statements in our piece above. He and his CRU colleagues have also put up an response to some of the false allegations in a previous piece in the UK Guardian. We’ll report further such developments as they happen.

2009 temperatures by Jim Hansen

Classé dans: — group @ 17 janvier 2010 - (English)

C’est le résumé pour 2009 de Hansen et collaborateurs’, (avec quelques modifications mineures).

“Si ça se réchauffe tant, bon sang, pourquoi fait-il si froid?”

par James Hansen, Reto Ruedy, Makiko Sato, and Ken Lo (Traduction par Xavier Pétillon)

Updates to model-data comparisons

Classé dans: — gavin @ 28 décembre 2009

It’s worth going back every so often to see how projections made back in the day are shaping up. As we get to the end of another year, we can update all of the graphs of annual means with another single datapoint. Statistically this isn’t hugely important, but people seem interested, so why not?
More »

Are the CRU data “suspect”? An objective assessment.

Kevin Wood, Joint Institute for the Study of the Atmosphere and Ocean, University of Washington
Eric Steig, Department of Earth and Space Sciences, University of Washington

In the wake of the CRU e-mail hack, the suggestion that scientists have been hiding the raw meteorological data that underpin global temperature records has appeared in the media. For example, New York Times science writer John Tierney wrote, “It is not unreasonable to give outsiders a look at the historical readings and the adjustments made by experts… Trying to prevent skeptics from seeing the raw data was always a questionable strategy, scientifically.”

The implication is that something secretive and possibly nefarious has been afoot in the way data have been handled, and that the validity of key data products (especially those produced by CRU) is suspect on these grounds. This is simply not the case. More »

CRU Hack: More context

Classé dans: — gavin @ 2 décembre 2009

Continuation of the older threads. Please scan those (even briefly) to see whether your point has already been dealt with. Let me know if there is something worth pulling from the comments to the main post.

In the meantime, read about why peer-review is a necessary but not sufficient condition for science to be worth looking at. Also, before you conclude that the emails have any impact on the science, read about the six easy steps that mean that CO2 (and the other greenhouse gases) are indeed likely to be a problem, and think specifically how anything in the emails affect them.

Update: The piece by Peter Kelemen at Columbia in Popular Mechanics is quite sensible, even if I don’t agree in all particulars.

Further update: Nature’s editorial.

Further, further update: Ben Santer’s mail (click on quoted text), the Mike Hulme op-ed, and Kevin Trenberth.