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Science

Trees give Insight into Northwest Africa’s Dry Past

New research of trees in northwest Africa has revealed droughts in the latter part of the 20th century are some of the fiercest experienced in that area.

[social_buttons]The research looked at tree rings in Morocco, Algeria and Tunisia and found that there have been frequent and severe droughts during the 13th and 16th centuries, as well as in the latter part of the 20th century.

A team of scientists from several countries used the information provided by tree rings to look back to the year 1179. One tree from Morocco dates all the way back to the year 883, while many of the oldest trees sampled contain climate data dating all the way back to the medieval period.

Much of North Africa has been recording weather information for some 50 years or less, but these research databases are far too short a time to provide any long-term understanding of regional climate. “Water issues in this part of the world are vital,” said lead researcher Ramzi Touchan, an associate research professor at University of Arizona ‘s Laboratory of Tree-Ring Research. “This is the first regional climate reconstruction that can be used by water resource managers.”

“One of the most important ways to understand the climate variability is to use the proxy record, and one of the most reliable proxy records is tree rings.” (A proxy record is a record of history obtained through observing natural phenomena, such as looking at the information provided by tree rings.)

The team is the first to provide a network of tree-ring chronologies across northwest Africa, analysing the patterns of past droughts over the whole region by looking at the tree rings of several different tree species. The width of the annual growth rings found inside a tree bear a very close relation to the amount of precipitation that has fallen. The team sampled various species of conifer and oak trees to give a better indicator of regional climate over the past thousand years, and found that the region’s 20th century drying trend matches what many climate models predict will happen as a result of climate change warming.

“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 added, “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.”

Touchan hopes to expand the teams network of samples to include Libya and additional parts of Algeria as well as expanding the chronology back through time using archaeological material. “If we can bridge this gap, it will be a discovery for the world,” Touchan said.

Source: University of Arizona

Image Source: Mossaiq




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