The Sahel, one of the hottest regions on Earth ranging from the Atlantic coast south of the Sahara Desert to the Red Sea to the east and the Horn of Africa to the southeast, is getting drier and drier and as a result trees are dying.

According to a Berkeley study due for publication in the Journal of Arid Environments on December 16, climate change is to blame.

In the 20^th century rainfall in the Sahel has dropped by 20 or 30 per cent. Causing the world’s most severe long-term drought since recording began. Previous research already pointed to climate change as the main cause of the drought. The drought-resilient trees of the Sahel are used to severe circumstances, but are overwhelmed by the conditions of the last few decennia.

Temperature rise and drastic rainfall decrease

The researchers found that as much as one in six trees died between 1954 and 2002 and one in five tree species disappeared locally. Especially fruit bearing and timber trees that require more water were affected, which put tremendous pressure on the food-security of the local inhabitants.

During the nearly fifty years that the study covers average temperatures ‘only’ rose by 0.8 degrees Celsius but rainfall dropped by as much as 48 per cent. These hotter and drier conditions formed the major driving factor of tree population development and soil makeup.

Especially the drying out of the soil is dramatic for the trees, not just killing a tree here and there, but eradicating entire species of trees. And it is shifting vegetation zones further south toward moister regions.

© Jorn van Dooren | www.bitsofscience.org