Much fun in the comments to Monbiot's Amazongate posting, with Daniel Nepstad, the activist-scientist behind some of the IPCC claims, having his say:
As the lead scientist on the research that underlies the IPCC statements about the sensitivity of the Amazon forest to reductions in rainfall, and after 25 years studying this question, I can say that the evidence has only grown stronger in support of this statement. I ran an enormous rainfall exclusion experiment in an Amazon forest that identified the rainfall threshold beyond which giant forest trees die quite suddenly (published in the journal Ecology in 2007). During the 2005 Amazon drought, tree mortality spiked up in permanent forest plots across the region (Philips et al. 2009 Science), providing further evidence of the drought threshold. The critics have latched onto two papers that seem to contradict our results, both using the same satellite sensor (MODIS). The forest canopy appears to get a bit greener in some Amazon regions during the dry season. Deeper analyses of the same data have found that these studies probably were seeing leaf-changing episodes and changes in cloudiness (which declines in the dry season) which are not evidence that the forests were not drought stressed. In a recent letter signed by 18 scientists including many of the world's authorities on tropical forest response to climate change, we found the IPCC statement to be sound and the NASA study involving MODIS data to be irrelevent to the IPCC statement. I would be happy to explain the science behind the IPCC statement.
Which is fascinating but still leaves us none the wiser as to where the idea that 40% of the Amazon is at risk from slight changes in rainfall comes from. Several commenters on the thread call Dr Nepstad on this evasion and demand to know in which paper it can be found.
No reply last time I looked.