the african great green wall

ScientificAmerican | Yacouba Sawadogo was not sure how old he was. With a hatchet slung over his shoulder, he strode through the woods and fields of his farm with an easy grace. But up close his beard was gray, and it turned out he had great-grandchildren, so he had to be at least sixty and perhaps closer to seventy years old. That means he was born well before 1960, the year the country now known as Burkina Faso gained independence from France, which explains why he was never taught to read and write.

Nor did he learn French. He spoke his tribal language, Mòoré, in a deep, unhurried rumble, occasionally punctuating sentences with a brief grunt. Yet despite his illiteracy, Yacouba Sawadogo is a pioneer of the tree-based approach to farming that has transformed the western Sahel over the last twenty years.

"Climate change is a subject I have something to say about," said Sawadogo, who unlike most local farmers had some understanding of the term. Wearing a brown cotton gown, he sat beneath acacia and zizyphus trees that shaded a pen holding guinea fowl. Two cows dozed at his feet; bleats of goats floated through the still late-afternoon air. His farm in northern Burkina Faso was large by local standards—fifty acres—and had been in his family for generations. The rest of his family abandoned it after the terrible droughts of the 1980s, when a 20 percent decline in annual rainfall slashed food production throughout the Sahel, turned vast stretches of savanna into desert, and caused millions of deaths by hunger. For Sawadogo, leaving the farm was unthinkable. "My father is buried here," he said simply. In his mind, the droughts of the 1980s marked the beginning of climate change, and he may be right: scientists are still analyzing when man-made climate change began, some dating its onset to the mid-twentieth century. In any case, Sawadogo said he had been adapting to a hotter, drier climate for twenty years now.

"In the drought years, people found themselves in such a terrible situation they had to think in new ways," said Sawadogo, who prided himself on being an innovator. For example, it was a long-standing practice among local farmers to dig what they called zai—shallow pits that collected and concentrated scarce rainfall onto the roots of crops. Sawadogo increased the size of his zai in hopes of capturing more rainfall. But his most important innovation, he said, was to add manure to the zai during the dry season, a practice his peers derided as wasteful.

Sawadogo's experiments proved out: crop yields duly increased. But the most important result was one he hadn't anticipated: trees began to sprout amid his rows of millet and sorghum, thanks to seeds contained in the manure. As one growing season followed another, it became apparent that the trees—now a few feet high—were further increasing his yields of millet and sorghum while also restoring the degraded soil's vitality. "Since I began this technique of rehabilitating degraded land, my family has enjoyed food security in good years and bad," Sawadogo told me.