This post will cover a lot of ground. I'm writing it having just read a PNAS paper from 2005 about a massive vegetation die-off event being tied to global climate change-type drought in the four-corner states. I have been thinking that such a study should be done as I read and learned about the various pine beetle epidemics afflicting Western North America. The paper, "Regional vegetation die-off in response to global-change-type drought" contains the kind of information that is critical in piecing a number of different threads together to weave a coherent story. The results contained within the paper, which can also be seen at this PNAS website, provide a profound message about the impacts of climate change. Such impacts have already occurred. As I've written recently (here and here, for example), they are growing in number and intensity. We ignore them at our (and the Earth's) peril.
A series of big messages I got from this paper can be summed up as follows. With human-forced climate change, warmer droughts are predicted to occur more often. One such drought has already occurred (and could be continuing to occur) in the southwestern U.S. That drought has had a profound impact on a large region's worth of vegetation. That impact came in two waves: the drought weakened the vegetation which then fell to the beetle epidemic. The beetles were able to spread due to the warmth that characterized this drought. With this and other region-wide die-offs, the potential for large changes in carbon stores is real we will face with their consequences. As a result, carbon-related policies must be prepared to take such die-offs (and their after-effects) into account. The failure of region-wide ecosystems, a disaster on its own, would also present a real danger to our society.
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