Part of me felt a little nostalgic yesterday watching the last Senate hearing on climate change that will be chaired by Sen. James Inhofe. It all felt very familiar and comforting in some strange way. There was the well-spoken ‘expert’ flown in from Australia (no-one available a little closer to home?), the media ‘expert’ from the think tank (plenty of those about) and a rather out-of-place geologist. There were the same talking points (CO2 leads the warming during the ice ages! the Medieval Warm Period was warm! it’s all a hoax!*) that are always brought up. These easy certainties and predictable responses are so well worn that they feel like a pair of old slippers.
[Read more…] about Inhofe’s last stand
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Medieval warmth and English wine
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
A New Take on an Old Millennium
The subject of reconstructions of temperature variations of the past millennium has been discussed many times before on this site (see e.g. here, here, here, and here). Despite the apparent controversy, the basic conclusion–that the global and hemispheric-scale warmth of the past few decades appears anomalous in a very long-term context–has stood up remarkably well in many independent studies (see Figure 1).
Figure 1. Reconstructions of Northern Hemisphere temperatures for the last 1000 years (various colored curves) compared with instrumental record (black curve).
[source: Wikipedia] (click to enlarge)
This is not to say that all estimates agree in their details. Indeed, there is a fair scatter among the various published estimates. [Read more…] about A New Take on an Old Millennium