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:6/14/2017)...  IBM (NYSE: IBM ) is introducing several innovative ... to developing collaboration between startups and global businesses, taking place ... the event, nine startups will showcase the solutions they have ... France is one ... a 30 percent increase in the number of startups created ...
(Date:5/6/2017)... 2017 RAM Group , Singaporean ... breakthrough in biometric authentication based on a ... to perform biometric authentication. These new sensors are based ... by Ram Group and its partners. This sensor will ... chains and security. Ram Group is a next ...
(Date:4/17/2017)... , April 17, 2017 NXT-ID, Inc. (NASDAQ: ... announces the filing of its 2016 Annual Report on Form 10-K ... Commission. ... 10-K is available in the Investor Relations section of the Company,s ... the SEC,s website at http://www.sec.gov . 2016 Year ...
Breaking Biology News(10 mins):
(Date:6/22/2017)... ... June 22, 2017 , ... ... clients throughout the biopharma and life sciences industries, continue to be in demand ... Tunnell’s Kip Wolf will be speaking on “The State of Information Governance in ...
(Date:6/20/2017)... ... June 20, 2017 , ... Biologist Dawn Maslar MS has ... her latest book, Men Chase, Women Choose: The Neuroscience of Meeting, Dating, Losing Your ... physiological effect on men. ”The logical next step, in my estimation, was to scientifically ...
(Date:6/20/2017)... CA (PRWEB) , ... June 20, 2017 , ... ... technology for discovery of antibody therapeutics from millions-diverse immune repertoires, announces launch of ... in San Diego, California. Dave Johnson, PhD, CEO of GigaGen, will present on ...
(Date:6/16/2017)... ... June 16, 2017 , ... ... commercialization, has just announced two more sessions of its “From the Helm” Webinar ... on the world of online templates for design control exercises. Led by David ...
Breaking Biology Technology:
Cached News: