February 19, 2009
Forests Absorb One Fifth Of Fossil Fuel Emissions
Researchers found that tropical forests are absorbing nearly a fifth of the CO2 released by burning fossil fuels, taking 4.8 billion tons of CO2 emissions from the atmosphere each year.
The British scientists found tropical trees have grown bigger over the past 40 years and are able absorb more fossil fuel emissions from the atmosphere, highlighting the need to preserve threatened forests.
The team used data collected from nearly 250,000 trees in the world's tropical forests over the past 40 years.
"To get an idea of the value of the sink, the removal of nearly 5 billion tons of carbon dioxide from the atmosphere by intact tropical forests, based on realistic prices for a ton of carbon, should be valued at around 13 billion pounds per year," said Lee White, Gabon's chief climate change scientist, who co-led the study.
Researchers suspect extra carbon dioxide in the atmosphere may be acting like a fertilizer and causing trees to get bigger and mop up more carbon.
However, scientists warned that while nature has provided a free subsidy for dealing with carbon emissions, it is one that won't last forever because trees can only grow so much bigger, said Simon Lewis, an ecologist at the University of Leeds who led the study.
"The trees are growing just a bit bigger but they make a big difference because there are so many trees and half their mass is carbon," Lewis said.
"Our study gives us another reason why it is really important to conserve tropical rain forests."
The U.N. Intergovernmental Panel on Climate Change reports that humans produce 32 billion tons of carbon dioxide worldwide each year.
However, only about 15 billion tons actually stays in the atmosphere and affects climate change. The new research reveals where some of the missing 17 billion tons are going.
"It's well known that about half of the 'missing' carbon is being dissolved in to the oceans, and that the other half is going somewhere on land in vegetation and soils, but we were not sure precisely where. According to our study about half the total carbon 'land sink' is in tropical forest trees," said Lewis.
The study coincides with a movement gaining worldwide support that protecting tropical forests is likely to be a key theme of the upcoming negotiations to limit carbon emissions in Copenhagen later this year.
Greenhouse gases are blamed for warming temperatures, which experts say will spark heat waves, droughts, more powerful storms, and higher sea levels.
Lewis said understanding what happens to the carbon dioxide pumped into the atmosphere will help researchers better understand future climate change.
"This is all about what is happening with the trees but we still don't know what is happening with the soils," said Lewis, who noted that oceans absorb about 8 billion tons of carbon dioxide each year.
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