Category Archives: Attribution

by Judith Curry

Is global warming slowing down? – David Appell

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by Shaun Lovejoy

When the International Meteorological Organization defined the first climate normal from 1900 to 1930, the belief was that the climate was constant, and that the newly defined climate ‘normal’ would give a close approximation to the climate.

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by Vaughan Pratt

The title of this post is taken from my AGU Fall Meeting poster presentation on the afternoon of Tuesday Dec. 4 (tomorrow).

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by Judith Curry

The recent articles in the Daily Mail and the Guardian are generating heated reactions – more heat than light.  Lets break down the arguments on both side and assess them systematically.

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by Judith Curry

Better models are needed before exceptional events can be reliably linked to global warming. – Nature

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by Judith Curry

These results support the notion that the enhanced wintertime warming over high northern latitudes from 1965 to 2000 was mainly a reflection of unforced variability of the coupled climate system. Some of the simulations exhibit an enhancement of the warming along the Arctic coast, suggestive of exaggerated feedbacks. – Wallace et al.

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by Judith Curry

Much is being made of Hansen’s ‘loaded dice’ as a metaphor for the changing climate.  I think we should be talking about ‘fuzzy dice.’

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by Judith Curry

Moreover, it appears likely that essentially all of this increase results from the human emission of greenhouse gases. These findings are stronger than those of the Intergovernmental Panel on Climate Change, the United Nations group that defines the scientific and diplomatic consensus on global warming. In its 2007 report, the I.P.C.C. concluded only that most of the warming of the prior 50 years could be attributed to humans.  -  Richard Muller, NYT op-ed

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by Judith Curry

“Climate dice”, describing the chance of unusually warm or cool seasons relative to climatology, have become progressively “loaded” in the past 30 years, coincident with rapid global warming.  We conclude that extreme heat waves, such as that in Texas and Oklahoma in 2011 and Moscow in 2010, were “caused” by global warming, because their likelihood was negligible prior to the recent rapid global warming. – Hansen, Sato, Ruedy

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by Judith Curry

The latest issue of the Bulletin of American Meteorological Society has published a collection of papers that illustrate different methodologies for attributing causes of recent extreme weather events.

Attribution of extreme events shortly after their occurrence stretches the current state-of-theart of climate change assessment. To help foster the growth of this science, this article illustrates some approaches to answering questions about the role of human factors, and the relative role of different natural factors, for six specific extreme weather or climate events of 2011. – TC Petersen, PA Stott, S. Herring

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by Judith Curry

“Our results also serve to highlight the importance of Atlantic multidecadal variability in mediating the rate of global warming, and they suggest that these variations deserve more explicit consideration in twentieth century climate simulations and in attribution studies based on recent observations of the rate of change of [global mean surface temperature]. — Wu et al. (2012)

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by Judith Curry

If Booth and colleagues’ results can be corroborated, then they suggest that multidecadal temperature fluctuations of the North Atlantic are dominated by human activity, with natural variability taking a secondary role. This has many implications. Foremost among them is that the AMO does not exist, in the sense that the temperature variations concerned are neither intrinsically oscillatory nor purely multidecadal.

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by Judith Curry

Nature’s exuberant smashing of daily high temperature records [in the U.S.] in recent weeks can only be described as “Meteorological March Madness”. Conditions more fitting of June than March prevailed east of the Rocky Mountains since the start of the month.  NOAA’s National Climate Data Center reported that over 7000 daily record high temperatures were broken over the U.S. from 1 March thru 27 March. 

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