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December 09, 2005

Forests and Global Warming.

Now we’re getting weird.

Johannes Feddema of the University of Kansas and six colleagues from the US National Centre for Atmospheric Research report in Science journal that they looked at changes in land use - the growth of cities, clearing of forests for agriculture, and draining of marshes - and their impact on climate change in the next 100 years. They confirmed something environmentalists have predicted for decades - the destruction of the Amazon forest would make the local climate 2C (4F) warmer because trees soak up carbon dioxide from the atmosphere, and burning them releases it. But then the scientists looked at temperate zones and found the opposite.

Simulations predicted the conversion of north American and European forests and grassland to agriculture would cool the region and counteract the effects of global warming by 25%-50%. This is because ripening corn and other staples would reflect more sunlight back into space, and release more moisture into the air, while dark forests would absorb sunlight and send thermometers soaring. Ken Caldeira and a Carnegie Institution team backed the finding in Geophysical Research Letters. "We were hoping to find that growing forests in the US would help slow global warming. But if we are not careful, growing forests could make global warming even worse."

If anyone has access to this paper I’d love to see it. So forests reduce warming because they soak up CO2 but crops reflect more sunlight so no forests reduces global warming.

Have they actually compared the two results to each other? Which effect wins out? Absorbing CO2 or reflecting sunlight?

December 9, 2005 in Climate Change | Permalink

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Comments

Presumably in the long term, it doesn't matter how much sunlight the crops reflect if there is a CO2 greenhouse blanket trapping the heat back in?

Posted by: dsquared | Dec 9, 2005 9:32:59 AM

Interesting.

I am surprised, though, that the mainstream enviro-industry let this one slip out. I mean, anything that hints that things may be a little more complex than their usual simplistic approach must be very damaging.

I'd like to see the report too.

RM

Posted by: The Remittance Man | Dec 9, 2005 11:59:01 AM

Dsquared, the crops would reflect light that can pass through CO2. The supposed issue with CO2 and other greenhouse gasses is trapping of infrared radiation. Otherwise the CO2 blanket wouldn't be an issue supposedly promoting global warming because solar radiation would not get to the surface but would be reflected.

Posted by: ATM | Dec 9, 2005 8:08:56 PM

What happens to the energy that is absorbed? could it by any chance be locked into the trees through photosynthesis and so not be absorbed as heat energy?

Posted by: Max Randor | Mar 13, 2006 9:51:00 PM