HOME >> BIOLOGY >> NEWS
Sahara's abrupt desertification started by changes in Earth's orbit, accelerated by atmospheric and vegetation feedbacks

WASHINGTON -- One of the most striking climate changes of the past 11,000 years caused the abrupt desertification of the Saharan and Arabia regions midway through that period. The resulting loss of the Sahara to agricultural pursuits may be an important reason that civilizations were founded along the valleys of the Nile, the Tigris, and the Euphrates. German scientists, employing a new climate system model, have concluded that this desertification was initiated by subtle changes in the Earth's orbit and strongly amplified by resulting atmospheric and vegetation feedbacks in the subtropics. The timing of this transition was, they report, mainly governed by a global interplay among atmosphere, ocean, sea ice, and vegetation. Their research is published in the July 15 issue of Geophysical Research Letters.

The researchers, headed by Martin Claussen of the Potsdam-Institut fuer Klimafolgenforschung (Potsdam Institute for Climate Impact Research) employed a model of intermediate complexity to analyze climate feedbacks during the past several thousand years of the current, or Holocene, era. Called CLIMBER-2 (for CLIMate and BiosphERe, version 2.1), the model led to the conclusion that the desertification of North Africa began abruptly 5,440 years ago (+/- 30 years). Before that time, the Sahara was covered by annual grasses and low shrubs, as evidenced by fossilized pollen.

The transition to today's arid climate was not gradual, but occurred in two specific episodes. The first, which was less severe, occurred between 6,700 and 5,500 years ago. The second, which was brutal, lasted from 4,000 to 3,600 years ago. Summer temperatures increased sharply, and precipitation decreased, according to carbon-14 dating. This event devastated ancient civilizations and their socio-economic systems.

The change from the mid-Holocene climate to that of today was initiated by changes in the Earth's orbit and the tilt of Earth's axis. Some
'"/>

Contact: Harvey Leifert
hleifert@agu.org
202-777-7507
American Geophysical Union
7-Jul-1999


Page: 1 2

Related biology news :

1. Analysis fingers causes of desertification
2. Scientists re-evaluating the meaning of desertification, Duke ecologist says
3. Battle between bubbles might have started evolution
4. Something got me started
5. UNC scientist finds chief AIDS cancer needs trauma and virus to get started
6. First experiments from NASA Commercial Space Centers get started on International Space Station
7. Adaptive changes in the genome may provide insight into the genetics of complex disease
8. Gene changes linked to increased eye pressure may have implications for glaucoma therapy
9. Study finds plant enzyme function changes with location in cell
10. Protein controls acid in cells by direct detection of volume changes, study finds
11. Gene mutation causes progressive changes to cell structure in children with Progeria

Post Your Comments:
*Name:
*Comment:
*Email:


(Date:3/23/2016)... Massachusetts , March 23, 2016 /PRNewswire/ ... im Interesse erhöhter Sicherheit Gesichts- und Stimmerkennung ... Xura, Inc. (NASDAQ: MESG ), ... bekannt, dass das Unternehmen mit SpeechPro zusammenarbeitet, ... aus der Finanzdienstleistungsbranche, wird die Möglichkeit angeboten, ...
(Date:3/21/2016)... 22, 2016 Unique technology ... for superior security   Xura, ... of secure digital communications services, today announced it is ... offer enterprise customers, particularly those in the Financial Services ... voice authentication within a mobile app, alongside, and in ...
(Date:3/15/2016)... 15, 2016 --> ... Transparency Market Research "Digital Door Lock Systems Market - Global ... 2023," the global digital door lock systems market in terms ... and is forecast to grow at a CAGR of 31.8% ... and medium enterprises (MSMEs) across the world and high industrial ...
Breaking Biology News(10 mins):
(Date:5/25/2016)... ... May 25, 2016 , ... Thailand’s ... at BIO 2016 in San Francisco. Located at booth number 7301, representatives from ... answer questions and discuss the Thai biotechnology and life sciences sector. , ...
(Date:5/25/2016)... ... 2016 , ... Scientists at the University of Athens say they have evidence ... hampering the research that could lead to one good one. Surviving Mesothelioma has just ... , The team evaluated 98 mesothelioma patients who got a second ...
(Date:5/24/2016)... ... 2016 , ... Cell therapies for a range of serious ... at Worcester Polytechnic Institute (WPI) that yielded a newly patented method of converting ... novel method, developed by WPI faculty members Raymond Page, PhD, professor of practice ...
(Date:5/23/2016)... ... 23, 2016 , ... The need for blood donations in South Texas and across the nation ... Blood & Tissue Center, blood donations are on the decline. In fact, donations across the ... 21 percent in South Texas in the last four years alone. , There is no ...
Breaking Biology Technology:
Cached News: