Reply To: Global warming threatens biodiversity


Guest commentary on RealClimate by Simon Lewis, a rainforest experts, rebuts claims a recent paper indicates the Amazon rainforest can withstand droughts, and hence won't be real affected by global warming.

[Stands to reason, really, that a rainforest needs, err, rain and plenty of it – but reason is not something Fox News n co are too bothered about.]


Rainforest persists above a threshold of rainfall, below which one finds savanna. If this threshold is crossed a landscape dominated by rainforest can ‘flip’ to savanna. Therefore a ’slight’ reduction can lead to a ‘dramatic’ reaction. Of course, evidence of a shift to a new lower rainfall climate regime is needed, and evidence of large areas of forest close to that rainfall threshold would be required for the IPCC statement to be reasonable; there is ample published evidence for both.

Overall the conclusions in the IPCC 2007 Fourth Assessment Report are strengthened (because the anomalous result of the Saleska et al. 2007 paper appear to be at fault), not weakened, by the new Samanta et al. study as their press release implies.

Up is Down, Brown is Green (with apologies to Orwell)