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Amazonian drought

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Translations: (Slovenčina) (English)

There has been a flurry of recent commentary concerning Amazon drought – some of it good, some of it not so good. The good stuff has revolved around a recently-completed interesting field experiment that was run out of the Woods Hole Research Center (not to be confused with the Woods Hole Oceanographic Institution), where they have been examining rainforest responses to drought – basically by using a very large rainproof tent to divert precipitation at ground level (the trees don’t get covered up). As one might expect, a rainforest without rain does not do well! But exactly what happens when and how the biosphere responds are poorly understood. This 6 year long field experiment may provide a lot of good new data on plant strategies for dealing with drought which will be used to improve the models and our understanding of the system.

The not-so-good part comes when this experiment is linked too directly to the ongoing drought in the southern Amazon. In the experiment, older tree mortality increased markedly after the third year of no rain at all (with around 1 in 10 trees dying). Since parts of the Amazon are now entering a second year of drought (possibly related to a persistent northward excursion of the ITCZ), the assumption in the Independent story (with the headline ‘One year to save the Amazon’) was that trees will start dying forest-wide next year should the drought continue. [Read more…] about Amazonian drought

Climate Feedbacks

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Guest Commentary by Brian Soden (RSMAS, Miami)

Current model estimates of the climate sensitivity, defined as the equilibrated change in global-mean surface temperature resulting from a doubling of CO2, range from 2.6 to 4.1 K, consistent with observational constraints (see previous article). This range in climate sensitivity is attributable to differences in the strength of ‘radiative feedbacks’ between models and is one of the reasons why projections of future climate change are less certain than policy makers would like. [Read more…] about Climate Feedbacks

Peter Doran and how misleading talking points propagate

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Peter Doran, the lead author on a oft-cited, but less-often read, Nature study on Antarctic climate in 2002 had an Op-Ed in the NY Times today decrying the misuse of his team’s results in the on-going climate science ‘debate’. As we discussed a while back (Antarctic cooling, global warming?), there is a lot of interesting stuff going on in Antarctica: the complexities of different forcings (ozone in particular), the importance of dynamical as well as radiative processes, and the difficulties of dealing with very inhomogeneous and insufficiently long data series. But like so many results in this field, it has become a politicized ‘talking point’, shorn of its context, that is mis-quoted and mis-used by many who should (and often do) know better. Doran complained about the media coverage of his paper at the time, and with the passage of time, the distortion has predictably increased. Give it another few years, maybe we’ll be having congressional hearings about it…

Disinformation? You want it, IREA’s got it

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RealClimate received a copy of a letter from the General Manager of the Intermountain Rural Electric Association (IREA, an energy cooperative in Colorado), Stanley R. Lewandowski (Jr), to other utilities (G&T’s in the jargon) in the US discussing fundraising and tactics for a new disinformation campaign on climate change (see Seth Borenstein’s piece yesterday).

This is enlightening on a number of levels. Firstly, though we knew that this stuff goes on, it’s rare that we get such a close look at how it happens. Secondly, who is to be the lead on this new campaign? None other than our old friend Patrick Michaels. Additionally, it is useful to see the reasons why some utilties are fighting against the idea of climate change set out more clearly than in their more carefully manicured press briefings. It might actually help people engage on the substance of their concerns rather than simply arguing about the science – which, as we are by now well aware, – is simply a path to gridlock.

We’ll highlight some of the best bits, and discuss what this all might imply below. [Read more…] about Disinformation? You want it, IREA’s got it

The missing piece at the Wegman hearing

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It’s not often that blogs come up in congressional hearings, but RealClimate was mentioned yesterday in the Energy and Commerce hearings on the ‘Hockey Stick’ affair. Of course, it was only to accuse us of being part of tight-knit social network of climate scientists, but still, the public recognition is nice.

There is much that could be said about the hearings (and no doubt will be) and many of the participants (Tom Karl, Tom Crowley, Hans von Storch, Gerry North) did a good job in articulating the big picture on climate change independently of the ‘hockey stick’ study as we’ve highlighted before. But it seems to us that there was a missing element in the discussions. That element was the direct implication of the critique that was the principal focus of Wegman’s testimony and that was mentioned periodically throughout the day. [Read more…] about The missing piece at the Wegman hearing

It’s different in Europe

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Paul Thacker has an interesting interview with a European and a US journalist on the media coverage of climate science in Europe. The standard contrarian line does not get as much attention there as it does in the US (which is good), but whether that means that the journalism there is actually better is a tricky point. So what makes for good climate science journalism and do they do it better over there?

Introducing RC forum

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It’s clear that there is a need to have some posts and discussions that specifically deal with up-to-the-minute articles and issues that we don’t necessarily want to cover in our usual detail. This might be related to a recent op-ed which just repeats the same talking-points as usual, or pointers to good discussions on other sites. To that end, we are introducing a separate category of post, called “RC forum”, where we will post these more minor items. Hopefully, this will help make interesting comment threads, which now sometimes occur under completely unrelated posts, easier to find and reference. The big pieces will still appear on the front page and in the RSS and Google feeds but the RC forum pieces will not. Right now, a notification email is sent out for every post, but we could restrict this to main page items if needed. There is now a link on the top bar to the RC Forum page and recent comments on Forum pieces will appear on the sidebar. Please let us know if you think this is a good idea or if you have ideas to improve it.

‘The Discovery of Global Warming’ update

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If you haven’t already seen the American Institute of Physics website by Spencer Weart on the ‘The Discovery of Global Warming’, we heartily recommend it. It provides both a summary of science, and more importantly, a history of how an obscure speculation from over one hundred years ago has become the scientific consensus of today. It has recently been updated with many more references from 1873 to the present, and so is even more worth reading. Spencer is very keen on getting feedback on the project, so don’t hesitate to let him know what you think.

Medieval warmth and English wine

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Never let it be said that we at RealClimate don’t work for our readers. Since a commenter mentioned the medieval vineyards in England, I’ve been engaged on a quixotic quest to discover the truth about the oft-cited, but seldom thought through, claim that the existence of said vineyards a thousand years ago implies that a ‘Medieval Warm Period‘ was obviously warmer than the current climate (and by implication that human-caused global warming is not occuring). This claim comes up pretty frequently, and examples come from many of the usual suspects e.g. Singer (2005), and Baliunas (in 2003). The basic idea is that i) vineyards are a good proxy for temperature, ii) there were vineyards in England in medieval times, iii) everyone knows you don’t get English wine these days, iv) therefore England was warmer back then, and v) therefore increasing greenhouse gases have no radiative effect. I’ll examine each of these propositions in turn (but I’ll admit the logic of the last step escapes me). I’ll use two principle sources, the excellent (and cheap) “Winelands of Britain” by geologist Richard C. Selley and the website of the English Wine Producers. [Read more…] about Medieval warmth and English wine

Runaway tipping points of no return

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Translations: (Slovenčina) (English)

I wonder if any else has noticed that we appear to have crossed a threshold in the usage of the phrase ‘tipping point’ in discussions of climate? We went from a time when it was never used, to a point (of no return?) where it is used in almost 100% of articles on the subject. Someone should come up with a name for this phenomenon….

Regardless of the recent linguistic trends, the concept has been around for a long time. The idea is that in many non-linear systems (of which the climate is certainly one), a small push away from one state only has small effects at first but at some ‘tipping point’ the system can flip and go rapidly into another state. This is fundamentally tied to the existence of positive feedbacks and is sometimes related to the concept of multiple ‘attractors’ (i.e. at any time two different ‘states’ could be possible and near a transition the system can flip very quickly from one to another). Another ‘tipping point’ in non-linear systems occurs when as some parameter varies, the current attractor changes character or disappears. However it is currently being used interchangeably a number of potentially confusing ways and so I thought I’d try and make it a little clearer.

[Read more…] about Runaway tipping points of no return