FAO warns of humanitarian disaster as a result of shrinking Lake Chad. The agency says the crisis in Lake Chad, which is surrounded by Cameroon, Chad, Niger and Nigeria should be urgently addressed. According to FAO, the lake, which was once one of the world's largest water bodies, has shrunk by 90 per cent, from 25,000 square kilometers in 1963 to less than 1,500 in 2001. It says this is due to climate variability, climate change and population pressure.