Featured Research

from universities, journals, and other organizations

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

Date:
May 26, 2010
Source:
University of Arizona
Summary:
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 developed the tree-ring-based drought history.

Ramzi Touchan of the University of Arizona's Laboratory of Tree-Ring Research takes a core from an Altas cedar, also known as Cedrus atlantica, in Morocco.
Credit: Photo courtesy of R. Touchan, 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 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."

In most of North Africa, instruments have been recording weather information for 50 years or less, too short a time to provide the long-term understanding of regional climate needed for resource planning, he said.

"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," said Touchan, an associate research professor at UA's Laboratory of Tree-Ring Research.

The team has developed the first systematically sampled network of tree-ring chronologies across northwest Africa, said co-author David Meko, also of UA's Laboratory of Tree-Ring Research.

The network allowed the researchers to analyze the patterns of past droughts over the whole region, said Meko, a UA associate research professor. The width of the annual growth rings on trees in semi-arid environments is highly correlated with the amount of precipitation.

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 is being published in the journal Climate Dynamics. The National Science Foundation funded the research.

The team sampled several different species of conifer and oak trees, because research indicates that testing several different species from the same region provides a better indicator of regional climate.

The current tree-ring chronology builds on previous work in northwest Africa by this team and by other researchers. The chronology incorporates samples from at least 20 trees from each of 39 different sites.

Persistent drought was more widespread across northwest Africa before the year 1500 than for the four centuries following, the researchers found. However, the pattern of widespread regional drought then seems to re-emerge in the late 20th century.

The spatial extent of the new regional tree-ring chronology revealed that drought in Morocco is not driven by the same kinds of oceanic and atmospheric conditions as drought in Algeria and Tunisia.

Drought in Morocco is strongly related to the north/south seesaw of air-pressure anomalies in the North Atlantic Ocean called the North Atlantic Oscillation. However, drought in Morocco is only weakly related to El Nino. By contrast, drought in Algeria and Tunisia appears more linked to a warm tropical Atlantic Ocean.

Touchan hopes to expand the new network's geographic reach to across North Africa, including Libya and additional parts of Algeria.

In addition, he wants to extend the chronology back in time to bridge the gap to archaeological material.

Tree-ring chronologies exist for centuries deep in the past, but they are "floating," meaning that there is no continuous record linking those chronologies to ones that reach back from the present, he said.

"If we can bridge this gap, it will be a discovery for the world," Touchan said.

Touchan and Meko's co-authors are Kevin J. Anchukaitis of Columbia University's Lamont Doherty Earth Observatory in Palisades, N.Y.; Mohamed Sabir of the National School of Forest Engineering in Sale, Morocco; Said Attalah of the University of Ourgla in Algeria; and Ali Aloui of the Institute of Sylvo-Pastoral of Tabarka in Tunisia.


Story Source:

The above story is based on materials provided by University of Arizona. The original article was written by Mari N. Jensen, College of Science. Note: Materials may be edited for content and length.


Journal Reference:

  1. Ramzi Touchan, Kevin J. Anchukaitis, David M. Meko, Mohamed Sabir, Said Attalah, Ali Aloui. Spatiotemporal drought variability in northwestern Africa over the last nine centuries. Climate Dynamics, 2010; DOI: 10.1007/s00382-010-0804-4

Cite This Page:

University of Arizona. "20th century one of driest in nine centuries for northwest Africa." ScienceDaily. ScienceDaily, 26 May 2010. <www.sciencedaily.com/releases/2010/05/100525181012.htm>.
University of Arizona. (2010, May 26). 20th century one of driest in nine centuries for northwest Africa. ScienceDaily. Retrieved July 25, 2014 from www.sciencedaily.com/releases/2010/05/100525181012.htm
University of Arizona. "20th century one of driest in nine centuries for northwest Africa." ScienceDaily. www.sciencedaily.com/releases/2010/05/100525181012.htm (accessed July 25, 2014).

Share This




More Plants & Animals News

Friday, July 25, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Boy Attacked by Shark in Florida

Boy Attacked by Shark in Florida

Reuters - US Online Video (July 24, 2014) An 8-year-old boy is bitten in the leg by a shark while vacationing at a Florida beach. Linda So reports. Video provided by Reuters
Powered by NewsLook.com
Goma Cheese Brings Whiff of New Hope to DRC

Goma Cheese Brings Whiff of New Hope to DRC

Reuters - Business Video Online (July 24, 2014) The eastern region of the Democratic Republic of Congo, mainly known for conflict and instability, is an unlikely place for the production of fine cheese. But a farm in the village of Masisi, in North Kivu is slowly transforming perceptions of the area. Known simply as Goma cheese, the Congolese version of Dutch gouda has gained popularity through out the region. Ciara Sutton reports. Video provided by Reuters
Powered by NewsLook.com
Dogs Appear To Become Jealous Of Owners' Attention

Dogs Appear To Become Jealous Of Owners' Attention

Newsy (July 23, 2014) A U.C. San Diego researcher says jealousy isn't just a human trait, and dogs aren't the best at sharing the attention of humans with other dogs. Video provided by Newsy
Powered by NewsLook.com
Professor Creates Site Revealing Where People's Cats Live

Professor Creates Site Revealing Where People's Cats Live

Newsy (July 23, 2014) ​It's called I Know Where Your Cat Lives, and you can keep hitting the "Random Cat" button to find more real cats all over the world. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

    Health News

      Environment News

        Technology News



          Save/Print:
          Share:

          Free Subscriptions


          Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

          Get Social & Mobile


          Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

          Have Feedback?


          Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
          Mobile: iPhone Android Web
          Follow: Facebook Twitter Google+
          Subscribe: RSS Feeds Email Newsletters
          Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins