There was a news article by Randolph E. Schmid (AP Science Writer) last Wednesday (September 24, 2008) which highlights another climate forcing [thanks to Ben Herman to alerting us to this news article].
The article is titled
The article starts with the text “Can a plague of beetles change the weather?” and proceeds to answer this question in the affirmative.
The article continues with the text
“Vegetation affects local weather by absorbing or reflecting sunlight and releasing chemicals and moisture. Changes can influence such things as rainfall, temperatures and smog…..’Forests help control the atmosphere, and there’s a big difference between the impacts of a living forest and a dead forest,’ NCAR scientist Alex Guenther, a principal investigator on the project, said in a statement. ‘With a dead forest, we may get different rainfall patterns, for example,’ he added……Indeed, preliminary computer modeling suggests that beetle kills of large forest areas can lead to temporary temperature increases of 2-to-4 degrees Fahrenheit, the researchers said.”
This news article is a useful summary of this local (and mesoscale) climate forcing. The only misimpression in the article is the statement that
”Living forests soak up carbon dioxide, while dead ones release it, potentially contributing to warming.”
Actually, while growing living forests (i.e. those increasing in biomass) can absorb more carbon than they emit during a year, dead trees from beetle kill may or may not release more carbon dioxide since it depends on whether the removal of the forest permits invigorated growth of new vegetation in the understory, as well as how rapidly the dead trees decompose.
Nevertheless, this is yet another example of the first order role of landscape change (both from natural and human management practices) on the climate system, that is summarized in
Pielke Sr., R.A., 2005: Land use and climate change. Science, 310, 1625-1626.