Read at : Google Alert – images of the Africa Drought
http://summitcountyvoice.com/2011/12/13/global-warming-warmer-drier-climate-kills-sahel-trees/
Global warming: Warmer, drier climate kills Sahel trees
by Bob Berwyn
By Summit Voice
SUMMIT COUNTY — Historic climate records, satellite images, aerial photography and tree-ring studies all tell the same story about trees in the sub-Sahara Sahel — the trees are dying and human-caused climate change is to blame.
“Rainfall in the Sahel has dropped 20-30 percent in the 20th century, the world’s most severe long-term drought since measurements from rainfall gauges began in the mid-1800s,” said researchers Patrick Gonzalez, who conducted the study while he was a visiting scholar at UC Berkeley’s Center for Forestry. “Previous research already established climate change as the primary cause of the drought, which has overwhelmed the resilience of the trees.”
The study, to be published Dec. 16 in the Journal of Arid Environments, focused on six countries in the Sahel, from Senegal in West Africa to Chad in Central Africa, at sites where the average temperature warmed up by 0.8 degrees Celsius and rainfall decreased as much as 48 percent.
They found that one in six trees died between 1954 and 2002. In addition, one in five tree species disappeared locally, and indigenous fruit and timber trees that require more moisture took the biggest hit. Hotter, drier conditions dominated population and soil factors in explaining tree mortality, the authors found. Their results indicate that climate change is shifting vegetation zones south toward moister areas.
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