🌧 An unusual shift in the weather has turned the Sahara green

Satellites recently captured plant life blooming in parts of the typically arid southern Sahara after storms moved there when they shouldn’t. It has also caused catastrophic flooding. And scientists say a world warming due to fossil fuel pollution is making both more likely.

Satellite imagery from NASA's MODIS satellite depicts vegetation extent (green coloring) over Africa on September 12, 2024, versus the same day in 2023. Vegetation reaches much farther north in 2024 in places like Niger and Chad and is more lush (darker green) just above the equator in a place like the Central African Republic. NASA

Rainfall north of the equator in Africa typically increases from July through September as the West African Monsoon kicks into gear.

The phenomenon is marked by an increase in stormy weather that erupts when moist, tropical air from near the equator meets hot, dry air from the northern portion of the continent. The focus for this stormy weather – known as the Intertropical Convergence Zone – shifts north of the equator in the Northern Hemisphere’s summer months. Much of it sags south of the equator during the Southern Hemisphere’s warm months.

But since at least mid-July, this zone has shifted farther north than it typically should, sending storms into the southern Sahara, including portions of Niger, Chad, Sudan and even as far north as Libya, according to data from NOAA’s Climate Prediction Center.

As a result, these portions of the Sahara Desert are anywhere from twice as wet to more than six times wetter than they should be.

The transition from El Niño to La Niña has influenced how far north this zone has moved this summer Haustein said. El Niño – a natural climate pattern marked by warmer than average ocean temperatures in the equatorial Pacific – typically leads to drier than normal conditions in the wet portions of West and Central Africa. La Niña, or even a budding one, can have the opposite effect.

A warming world is the other significant factor.

“The Intertropical Convergence Zone, which is the reason for (Africa’s) greening, moves farther north the warmer the world gets,” Haustein explained. “At least, this is what most models suggest.”

🔗 https://edition.cnn.com/2024/09/13/weather/sahara-desert-green-climate/index.html