Tuesday, November 21, 2006
Cooling Forest Fires
Scientists now think that forest fires could actually decrease global warming.
Forests absorb carbon dioxide in the atmosphere, creating what scientists call carbon sinks. Global warming causes droughts and longer summers, so there are more forest fires, which destroy these sinks and release carbon dioxide back into the atmosphere. But a new study published in the journal Science shows that when there are fewer northern boreal forests, more light is reflected back into space, decreasing the absorption of greenhouse gases in the atmosphere.
After a northern forest burns to the ground, scientists think that evergreen forests will be replaced by deciduous forests when the earth is warmer. These deciduous saplings have lighter green leaves than mature trees, so they reflect more light. They also shed their leaves in the fall and winter, so snow that falls to the ground will also reflect more light.
How's that for an unexpected negative feedback loop? After all this talk about how global warming is going to fuel itself, this study show that we still don't exactly know all the systems in play.