Sahara on EARTH Magazine

Saharan dust a storm killer

Fri, 12 Oct 2018 13:11:29 -0400

NASA satellite imagery shows Saharan dust crossing the Atlantic Ocean into the Gulf of Mexico, where the dust may suppress developing storm systems. Credit: NASA/Texas A&M University.

Each year between 900 million and 4 billion metric tons of dust from the Sahara Desert in Africa is swept into the atmosphere and blown around the world. In places like Texas, the dust often leads to poor air quality. A new study suggests that desert dust may also suppress the formation of severe storms and hurricanes in the southern United States.

Weedy seeds gathered in once-green Sahara

Tue, 05 Jun 2018 16:36:57 -0400

Today, the vast and arid Sahara Desert seems an unlikely place to find early signs of seed gathering and plant cultivation in Africa, but new evidence shows that, 10,000 years ago, people were collecting, sorting and saving seeds near a rock shelter known as Takarkori.

Tropical rainfall shifts resulted in greener Sahara

Tue, 18 Apr 2017 12:14:56 -0400

Thousands of years ago, the Sahara was dotted with lakes and vegetation. Credit: Wonker, CC BY 2.0.

Six thousand years ago, the Sahara — today the world’s largest nonpolar desert, stretching over an area larger than the contiguous United States — was dotted with lakes and vegetation. Rock paintings from that time depict a much wetter landscape, and show elephants, hippos, antelope and many other animals living in the region.

Blogging on EARTH: Second dispatches from EGU

Thu, 05 Jan 2012 06:41:58 -0500

EARTH’s Carolyn Gramling is in Vienna, Austria, at the European Geophysical Union meeting this week. Here are a few more sessions that she has found interesting (for more from the meeting, see her first “Dispatches”).

Differentiating natural from human influence on the Sahel

The Sahel, the semi-arid transition zone south of the Sahara Desert, supports about 50 million inhabitants and is particularly vulnerable to changes in precipitation. In 1975, meteorologist Jule Charney of MIT suggested that desertification in the region — the advance of the Sahara into the Sahel — might be due to overgrazing, through a biogeophysical feedback mechanism. Charney suggested that the removal of vegetative cover would increase the albedo over the region, reflecting more radiative energy back into space. That, in turn, would reinforce the sinking circulation of dry air masses in the troposphere; those dry air masses would produce less rainfall, which in turn would foster even less plant growth.