Smoke from the Amazon forest during a fire in Brazil, 23 August 2019. (Image: EPA/Joedson Alves)

In Sao Paulo, on August 19, day turned into night. The sun was blocked as smoke blew in, and the pictures went around the globe.

The fires in the Amazon rainforest are part of the process of land clearing, and they are a regular feature of the dry season, but this year's fires are worse than they have been for several years as land clearing increases under the new regime of Brazilian President Jair Bolsonaro.