Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

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

26.05.2010
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, "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.

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.

Contact information:
Ramzi Touchan, 520-621-2992
rtouchan@ltrr.arizona.edu
languages spoken: English, Arabic
David Meko, 520-621-3457
dmeko@ltrr.arizona.edu
Related Web pages:
Ramzi Touchan
http://www.ltrr.arizona.edu/~rtouchan
David Meko
http://www.ltrr.arizona.edu/~dmeko/
UA's Laboratory of Tree-Ring Research
http://www.ltrr.arizona.edu

Jennifer Fitzenberger | EurekAlert!
Further information:
http://www.arizona.edu

Further reports about: Africa Algeria Morocco Pacific Ocean climate models regional climate

More articles from Earth Sciences:

nachricht GPM sees deadly tornadic storms moving through US Southeast
01.12.2016 | NASA/Goddard Space Flight Center

nachricht Cyclic change within magma reservoirs significantly affects the explosivity of volcanic eruptions
30.11.2016 | Johannes Gutenberg-Universität Mainz

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

Im Focus: MADMAX: Max Planck Institute for Physics takes up axion research

The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.

The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...

Im Focus: Molecules change shape when wet

Broadband rotational spectroscopy unravels structural reshaping of isolated molecules in the gas phase to accommodate water

In two recent publications in the Journal of Chemical Physics and in the Journal of Physical Chemistry Letters, researchers around Melanie Schnell from the Max...

Im Focus: Fraunhofer ISE Develops Highly Compact, High Frequency DC/DC Converter for Aviation

The efficiency of power electronic systems is not solely dependent on electrical efficiency but also on weight, for example, in mobile systems. When the weight of relevant components and devices in airplanes, for instance, is reduced, fuel savings can be achieved and correspondingly greenhouse gas emissions decreased. New materials and components based on gallium nitride (GaN) can help to reduce weight and increase the efficiency. With these new materials, power electronic switches can be operated at higher switching frequency, resulting in higher power density and lower material costs.

Researchers at the Fraunhofer Institute for Solar Energy Systems ISE together with partners have investigated how these materials can be used to make power...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

UTSA study describes new minimally invasive device to treat cancer and other illnesses

02.12.2016 | Medical Engineering

Plasma-zapping process could yield trans fat-free soybean oil product

02.12.2016 | Agricultural and Forestry Science

What do Netflix, Google and planetary systems have in common?

02.12.2016 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>