A skeleton of a fish lies forgotten on the dry bed of Lake Peñuelas outside Santiago, Chile. Eliseo Fernandez/Reuters
The planet appears to be undergoing a mass extinction: the sixth time in the history of life on Earth that global fauna has experienced a major collapse in numbers.
Historically, mass extinctions have been caused by catastrophic events like asteroid collisions. This time, human activities — including deforestation, mining, and carbon dioxide-emissions — are to blame.