An imminent return to drought in the western Sahel?

Area of Science:

• Climatology
• Environmental Science
• Meteorology

Background:

• The semi-arid Sahel experienced a severe, uniform drought in the 1970s and 1980s.
• Post-drought recovery patterns show a divergence between the western Sahel and its central and eastern regions.

Purpose of the Study:

• To investigate the drivers of uniform drought variation and the emerging east-west contrast in the Sahel.
• To project future climate trajectories for different Sahelian regions.

Main Methods:

• Analysis of instrumental climate observations.
• Climate simulations using constant and time-varying external forcing models.

Main Results:

• Both uniform variation and east-west contrast patterns are evident in historical data and simulations.
• 20th-century external forcing amplified uniform drought variations.
• Global warming-strengthened monsoons initiated the east-west contrast.
• Projected North Atlantic cooling in the mid-21st century will exacerbate this contrast, leading to a drier west and wetter center/east.

Conclusions:

• The Sahel's climate future is regionally divergent, with the west facing increased aridity.
• Monsoon dynamics and North Atlantic temperature gradients are key factors influencing Sahelian rainfall patterns.