In 1986, a freshwater lake in Cameroon released a cloud of carbon dioxide that killed 1,746 people in a single night, and that lake is one of only three on Earth known to be capable of this, the largest of which sits beneath roughly two million people."

In 1986, a freshwater lake in Cameroon released a cloud of carbon dioxide that killed 1,746 people in a single night, and that lake is one of only three on Earth known to be capable of this, the largest of which sits beneath roughly two million people."

On the evening of 21 August 1986, in a remote part of northwestern Cameroon, the surface of a small crater lake known as Lake Nyos exhibited a brief disturbance. A fountain of water and foam rose, by later reconstruction, approximately a hundred metres above the lake. The disturbance lasted for a short period and subsided. The lake returned to stillness. What had happened, in those few minutes, was that approximately 100,000 to 300,000 tons of c…