The prolonged drought in northwest Africa from 1999-2002 killed many Atlas cedar trees. This photo is from a site in Algeria where tree-ring researcher Ramzi Touchan took samples to develop a drought history of the region. The trees, also known as Cedrus atlantica, are native to the Atlas Mountains of northwest Africa. Credit: Photo courtesy of R. Touchan, University of Arizona.

(University of Arizona) Droughts in the late 20th century rival some of North Africa's major droughts of centuries past, reveals new research that peers back in time to the year 1179. The first multi-century drought reconstruction that includes Morocco, Algeria and Tunisia shows frequent and severe droughts during the 13th and 16th centuries and the latter part of the 20th century. An international team led by a University of Arizona researcher developed the tree-ring-based drought history.

Droughts in the late 20th century rival some of North Africa's major droughts of centuries past, reveals new research that peers back in time to the year 1179.

The first multi-century drought reconstruction that includes Morocco, Algeria and Tunisia shows frequent and severe droughts during the 13th and 16th centuries and the latter part of the 20th century.

An international research team figured out northwest Africa's climate history by using the information recorded in tree rings. The oldest trees sampled contain climate data from the medieval period. One tree-ring sample from Morocco dates back to the year 883.

"Water issues in this part of the world are vital," said lead researcher Ramzi Touchan of the University of Arizona. "This is the first regional climate reconstruction that can be used by water resource managers." …

The team found the region's 20th-century drying trend matches what climate models predict will occur as the climate warms. The research is the first to compare projections from climate models with tree-ring-based reconstructions of the region's past climate.

The region's trees and dead wood needed to do such research are disappearing rapidly from a combination of a massive die-off of trees, logging and population pressures, Touchan said.

"We have a chance to do what we call salvage dendrochronology," Touchan said. These are areas where we need to get this information now or it's going to disappear."

Pointing to a cross-section of an old tree from Morocco, he said, "This is from 883 -- and this is from a stump. If we don't take them, they're gone. So this is a real treasure."

The team's paper, "Spatiotemporal drought variability in northwestern Africa over the last nine centuries," is now available online and will be published in a future issue of the journal Climate Dynamics. A complete list of authors and their affiliations is at the bottom of this release. The National Science Foundation funded the research. …

20th century one of driest in 9 centuries for northwest Africa

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