I just started reading Six Degrees: Our Future on a Hotter Planet (thank you Seattle Public Library!) and wanted to share something I ran across last night that I thought was interesting.
Apparently, it is quite common that, during periods of drought, plants act differently regarding absorbing CO2. For example, during the heatwave of 2003 in Europe, not only did scientists see a 30 percent drop in plant growth across the continent (due to high temperatures and drought), but instead of absorbing carbon dioxide from the air, the stressed plants actually began to emit it.
Around a half a billion tons of carbon was added to the atmosphere that summer as a result, which is the equivalent to one-twelfth of the total global emissions from fossil fuels. In fact, during the 1998 - 2002 droughts in the Northern Hemisphere, over a billion tons of extra carbon poured out of the plants and soils in response to the drought and heat. [p. 82]
So, there's another one of those hidden variables that isn't very obvious. It's bad enough that there's such dramatic impact as a result of higher temperatures on the planet, but I still can't get over the fact that 10,000 people died in Paris that summer (2003) from heatstroke. Can you imagine that happening in any one of our American cities? Do you think we are at all better equipped to deal with that many patients than Paris? I doubt it.
I'll share more tidbits with you as I read them!