What will Africa’s ‘Great Green Wall’ mean for climate change?

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Women walk under filao trees planted to slow coastal erosion along the Atlantic Ocean in Lompoul village near Kebemer, Senegal, on Friday, Nov. 5, 2021. The trees form a curtain that protects the beginning of the Great Green Wall, a project that began in 2007 with a vision for the trees to extend like a belt across the vast Sahel region, from Senegal in the west to Djibouti in the east, by 2030. But as temperatures rose and rainfall diminished, millions of the planted trees died. (AP Photo/Leo Correa)

(KXAN) — Back in the 1970s and 80s, the area just south of the Saharan Desert, known as the Sahel, began to turn barren with worsening drought. The Sahel was known as a fertile stretch of land before this time and brought food security and seasonal monsoon rains to the regions nearby.

But food and water have become a scare commodity since those days — which is why the African Union launched Africa’s “Great Green Wall” initiative in 2007. The goal, which is about 15% complete, is to plant 100 million hectares of trees along the Sahel, or nearly 5,000 miles from Senegal to Djibouti.

The green line across Africa is where the Great Green Wall is being planted

Further goals are to halt the Saharan Desert from expanding south by tapping into the water cycle. More trees means more water cycling from soil to the atmosphere. The darker colors from more trees (as opposed to lighter colors of the sand) means more heat retention. More trees also reduces the amount of dust in the atmosphere, which means more solar radiation can reach the surface, as opposed to being reflected off the dust particles.

In all, the hope is that all of this will lead to a stronger monsoon for Central Africa and reverse the effects of desertification.

Women walk under filao trees planted to slow coastal erosion along the Atlantic Ocean in Lompoul village near Kebemer, Senegal, on Friday, Nov. 5, 2021. The trees form a curtain that protects the beginning of the Great Green Wall, a project that began in 2007 with a vision for the trees to extend like a belt across the vast Sahel region, from Senegal in the west to Djibouti in the east, by 2030. But as temperatures rose and rainfall diminished, millions of the planted trees died. (AP Photo/Leo Correa)

The idea might sound a little farfetched, but the practice has been done before here in the U.S.

From 1935 to 1942, then President Franklin Roosevelt conjured what was known as his “tree army”, or the Civilian Conservation Corps and Works Progress Administration workers. Their goal? To plant as many trees from Canada through Texas, bisecting the nation and prevent the wind erosion that was causing the Dust Bowl.

Francesco Pausata, a climate dynamicist at the Université du Québec à Montréal reports to Sciencenews.org after running several global climate models. Pausata says that model runs with the Great Green Wall in Africa (with current climate change trends) would reduce summertime temperatures by as much as 1.5 degrees Celsius for most of the Sahel. At the same time, the Sahel’s hottest areas would actually see increases in temperatures by about the same rate.

In terms of precipitation, Pausata says that with the implementation of the Great Green Wall would increase precipitation across all of the Sahel and even double in some areas, according to his research.

The simulations also suggest a stronger African Monsoon to have far reaching effects in other global climate patterns, such as shifting the El Niño Southern Oscillation farther west and even having effects on the tracks of tropical cyclones.

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