Burkhard Bilger travels to sub-Saharan Africa, where he reports on a “thrillingly simple” undertaking by eleven nations to halt desertification. They are planting a “Great Green Wall” of trees, in “a column nine miles wide and almost five thousand miles long.” If completed, “it will be the largest feat of horticulture in human history.”

http://www.newyorker.com/magazine/2011/12/19/the-great-oasis?