Monday, November 17, 2008

Another Point for the Side that Says Boreal Forests Do Cool the Planet



A scientific article raised quite a stir last year when the media coverage in response to it suggested that boreal forests might actually contribute to global warming because the cooling effects of carbon sequestration were overwhelmed by the effect of the heat absorbed by their dark green colour.

The result didn't seem to ring true with people.

Over the past few months, new scientific papers have lent more support to the idea that boreal forests are in fact coolers of the climate. First, a article in the September issue of Nature observed that old growth forests continue to sequester carbon much longer than is conventionally thought, increasing the cooling contribution from sequestration. Now, a new study published in The Philosophical Transactions of the Royal Society suggests that forests also release chemicals called terpenes that contribute to cloud formation, which in turn cool the planet by reflecting the sun's rays. The authors call into question the previous conclusion that dark forests would, on balance, result in atmospheric warming because they ignored factors such as cloud formation. (What the heck is terpene?)

So... a point for the northern-forests-as-climate-shield team (not sure what the score is currently). It's worth remembering though, that none of this scientific debate ever questions the fact that natural, unlogged forests store more carbon than commercial forests... forest protection remains an important climate change mitigation strategy.

Thanks to Carbon Positive, where you can find the original story that inspired this post and to Sean Cadman for passing it on to me.

Photo credit: Terpenes are a major component of conifer resin, shown in this picture from Wikipedia.

2 comments:

TJGray said...

Seems to make sense to me that forests, which pump water vapour into the, slow down water runoff and reduce surface temperatures would be helpful to mitigate the increased temps associated with climate change.

Chris Henschel said...

Well it appears that common sense and science may be starting to converge on this question.