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:12/15/2016)... Canada and BADEN-BADEN, Germany , ... a leading global financial services provider, today announced an agreement ... passive behavioural biometrics, to join forces. The partnership will enable ... mitigation strategies in compliance with local data protection regulation. ... In order ...
(Date:12/15/2016)... Dec. 15, 2016 Advancements in ... health wellness and wellbeing (HWW), and security ... three new passenger vehicles begin to feature ... recognition, heart beat monitoring, brain wave monitoring, ... monitoring, and pulse detection. These will be ...
(Date:12/12/2016)... -- Researchers at Trinity College, Dublin, are opening up ... material with Silly Putty. The mixture (known as "G-putty") ... sense pulse, blood pressure, respiration, and even the ... The research team,s findings were published Thursday in ... Due ...
Breaking Biology News(10 mins):
(Date:1/19/2017)... and GAITHERSBURG, Md. , ... PIP) and Altimmune, Inc., a privately-held immunotherapeutics company ... a definitive agreement for the merger of PharmAthene ... investors include Novartis Venture Fund, HealthCap, Truffle Capital ... a fully-integrated and diversified immunotherapeutics company with four ...
(Date:1/19/2017)... 2017 AquaBounty Technologies, Inc. (AIM: ABTU; NASDAQ: ... aquaculture and a majority-owned subsidiary of Intrexon Corporation (NYSE: ... the listing of its common shares on the NASDAQ ... "AquaBounty,s listing on NASDAQ represents an important ... to the U.S. markets as we advance plans for ...
(Date:1/19/2017)... ... January 18, 2017 , ... LabRoots , the leading ... the world, was today awarded the "Best Science & Technology Social Networking Service ... and decided upon by a dedicated team of researchers and analysts. , The ...
(Date:1/19/2017)... ... January 19, 2017 , ... ... the full spectrum of drug and device development, and Prism Clinical Research ... and clinicians, today announced Verified Clinical Trials (VCT) has been selected ...
Breaking Biology Technology:
Cached News: