Even rainforests can endure droughts, and when that happens, it seems that the usual carbon-sink behavior of the forest goes into reverse full speed. A major study of the 2005 drought in the Amazon has shown that, instead of absorbing 2 billion tons of carbon dioxide in 2005, as it would normally have done, the Amazon *released* about 3 billion tons.
One article on the effects of the drought: http://www.cbc.ca/technology/story/2009/03/05/carbon-sink.html A search for "drought amazon" got over 800,000 hits so there's a lot about this out there. For those of you who, like me, apparently slept through 2005 and were unaware that there even was a drought in the Amazon, here's an old article which talks about it. It was apparently very severe, which seems pretty scary all by itself (I mean, this is a rainforest f'gosh sakes, it's not supposed to have droughts): http://news.bbc.co.uk/2/hi/americas/4344310.stm They had the Brazilian army delivering water to people (taking water to the Amazon!!), boats were stranded when the river level dropped, millions of fish died on the beaches (and no doubt stank to high Heaven) -- big mess. I have to wonder if a drought in that region is a harbinger of future bad changes, possibly caused by cutting too much of the forest and passing some ill-perceived "tipping point"...?
