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The Sahara Desert is expanding—world’s largest desert grew by 10 percent since 1920

Phys.org/news (MARCH 29, 2018 )

Titre : The Sahara Desert is expanding—world’s largest desert grew by 10 percent since 1920

The Sahara Desert has expanded by about 10 percent since 1920, according to a new study by University of Maryland scientists. The research is the first to assess century-scale changes to the boundaries of the world’s largest desert and suggests that other deserts could be expanding as well. The study was published online March 29, 2018, in the Journal of Climate.

Phys.org/news (MARCH 29, 2018 )

Présentation
Deserts are typically defined by low average annual rainfall—usually 100 millimeters (less than 4 inches) of rain per year or less. The researchers analyzed rainfall data recorded throughout Africa from 1920 to 2013 and found that the Sahara, which occupies much of the northern part of the continent, expanded by 10 percent during this period when looking at annual trends.

When the authors looked at seasonal trends over the same time period, the most notable expansion of the Sahara occurred in summer, resulting in a nearly 16 percent increase in the desert’s average seasonal area over the 93-year span covered by the study.

The study results suggest that human-caused climate change, as well as natural climate cycles such as the Atlantic Multidecadal Oscillation (AMO), caused the desert’s expansion. The geographical pattern of expansion varied from season to season, with the most notable differences occurring along the Sahara’s northern and southern boundaries.

The southern border of the Sahara adjoins the Sahel, the semi-arid transition zone that lies between the Sahara and the fertile savannas further south. The Sahara expands as the Sahel retreats, disrupting the region’s fragile grassland ecosystems and human societies. Lake Chad, which sits in the center of this climatologically conflicted transition zone, serves as a bellwether for changing conditions in the Sahel.

Source  : University of Maryland

Annonce (Phys.org/news)

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