Can a mighty 'green wall' of trees transform sub-Saharan Africa, hold back the desert, reverse climate change and put a stop to the waves of migration to Europe? Joe Shute meets the people betting $8 billion on it. Photographs by Simon Townsley

Water is life in the Lake Chad basin. For centuries the lake was the largest reservoir in the Sahel – the semi-arid belt spanning Africa south of the Sahara Desert – relied upon by 30 million people.

Naturally shallow and replenished by monsoon rains, the Chari River from the south and the Yobe from the north-west, the lake – which once covered eight per cent of the continent – has always ebbed and flowed. But in recent decades these seasonal variations have stalled. Modern satellite images show an isolated blue dot in the middle of an arid desert. Lake Chad is vanishing.

Adam Abdullah lives on the edge of this dot. He is 75, a rarity in Chad, the country with the world’s lowest life expectancy (53 for men and 54 for women), and has made a home for himself in a conical shelter built from dried rushes above an evaporated part of the lake. He moved to his present accommodation on the outskirts of a village called Melea four years ago, after Boko Haram militants launched a night-time assault on his ancestral home.

‘Many people died and many houses were destroyed,’ he says. A decade ago his cattle died in a famine. Now he is waiting here, hoping for a sliver of land on which to plant crops. Gesturing out over the dried lakebed where swallows dip and dive in pursuit of hatching insects, he tells me: ‘There used to be water all around here, but I have watched it disappear.’ Lake Chad, which spanned 9,652 square miles in 1963, has shrunk by an estimated 90 per cent in recent decades. Climate change is to blame in particular, say experts, with population growth and unplanned irrigation also contributing to what the United Nations Environment Programme calls an ‘ecological disaster’ – one fuelled by the Islamist terrorist group Boko Haram, which 10 years ago sprang up in the Lake Chad basin.

The ongoing conflict has claimed tens of thousands of lives and displaced an estimated 2.5 million people in the region. Families who for generations depended on the lake to sustain them now languish in front of a horizon of sand.

On the other side of Melea, women in brightly patterned cloth and men in long loose-fitting robes gather about the community well. During periods of drought they come here to pray for rain. Today, in holes dug into the sand and lined with goat poo, they are planting seeds of acacia, desert date, guava, citron and mango trees.

‘In five years the sand has come so quickly towards our crops,’ explains Mbodou Mahamat, who is president of the village’s agriculture scheme. ‘Our community has been here for 400 years and now we are watching the lake go down. I’m afraid if there is no water then we will die. Read fiurther the whole article using the link above