BBC: The UN predicts over 50 million people will be forced to leave their homes by 2020 because their land has turned to desert. This is already happening in Senegal, writes Laeila Adjovi.
Cattle herder Khalidou Badara took me up a hill in Louga, northern Senegal, to describe to me how his area has changed.
"When I was a child, I did not even dare to walk up to here because the vegetation was so dense.
"But these past few years, the wind and sand have been taking over.
"There are almost no...