The world’s forests are an enormous carbon sink, meaning they absorb
massive quantities of carbon dioxide, through the processes of
photosynthesis and respiration. In normal years the Amazon alone
absorbs three billion tons of carbon, more than twice the quantity
human beings produce by burning fossil fuels. But during the 2005
drought, this process was reversed, and the Amazon gave off two billion
tons of carbon instead, creating an additional five billion tons of
heat-trapping gases in the atmosphere. That’s more than the total
annual emissions of Europe and Japan combined.
If we can restrain global warming, we have a chance, explains environmental author Paul Brown:
Significantly, [Oliver] Phillips also found that the 2005 drought was not the
result of El Niño, the cause of previous smaller episodes, but of a
regional rise in sea temperatures—one of the expected early signs of
global warming. Taken together, these findings suggest that climate
change could trigger the worst kind of vicious cycle, with climbing
temperatures causing the rainforests to dry out and give off massive
quantities of greenhouse gases, which in turn causes the planet to warm
more rapidly—a dynamic with harrowing implications. An article last
year in Proceedings of the National Academy of Science
identified rainforest-wide dieback in the Amazon, along with the
melting of the Arctic sea ice, as among the nine most crucial "tipping
points" that must be staved off to prevent catastrophic climate change.
One wonders if this variability in the Amazon could explain much of the global variability in carbon output, a swing as much as 2.4 gigatons a year.
In any case, here's a scary picture of what drought looks like in the Amazon, when a vast tributary dried up and stranded a ferry, from the Washington Monthly special issue on the Amazon.
Encouragingly, the experts think they have an answer — using money to encourage locals to save their forests, or REDD, for Reducing Emissions from Deforestation and Forest Degradation. It's on the agenda at Copenhagen…