France, Sept. 24 -- The Climate Impact Lab, a research group based at the University of Chicago, predicts there will be 66,800 extra deaths across the Sahel, the dry belt along the southern edge of the Sahara, between September and February compared with a normal year.

Nigeria alone accounts for 31,400 of these, followed by Sudan with 17,500, Niger with 10,000 and Chad with 8,000.

Worldwide, around 239,000 more heat-related deaths are likely to be seen over the same six months. Counting from June, when the current El Nino began, the estimated global toll rises to 451,000 by the end of February.

"This is such a large number that it can be numbing, but it is made up of parents and children, grandparents and neighbours, people going to wo...