In the afternoon of August 20th this year, the sky over Brazil’s largest city, Sao Paulo turned dark. The cause of this premature night was the smoke from fires burning thousands of kilometres away in the Amazon rainforest.

The scale of the fires caught the attention of the world, but the Amazon is one story among many. The global community has long worried about deforestation, five years ago nations agreed to work to halve global tree loss by 2020 and end it by 2030. This month, those targets were acknowledged to be missed.

This week we investigate what tactics are being used to preserve forests around the world, and ask if any of them are effective.

image: View of a burnt area of forest in Para state, Brazil, in the Amazon basin. Credit Joao Laet/Getty Images.