This reminds me of a thought I had about the Boreal forest. It's huge, almost encircling the northern hemisphere. It's growth is sharply limited by the short growing season, but even so it already represents a large carbon sink due to its size. As the climate warms, I wonder how much negative feedback we might get as tree growth accelerates.
But... only if we don't cut it down.
OTTAWA - Canada’s boreal forest is a ticking “carbon bomb” and its continued logging could trigger a massive release of greenhouse gases, says a new report.
A Greenpeace study released Thursday says cutting down trees in the boreal forest is exacerbating climate change by releasing stores of greenhouse gases trapped in soil and vegetation.
It also found that logging makes the forest more susceptible to insect outbreaks and wildfires which, if widespread, could cause a spike in greenhouse-gas emissions - the so-called “carbon bomb.”
http://www.commondreams.org/archive/2008/04/10/8206/