Explainer: Why are the Amazon fires sparking a crisis for Brazil - and the world?

A record number of fires ravaging the Amazon has drawn international outrage because of the rainforest's importance to the global environment and prompted Brazilian President Jair Bolsonaro to dispatch the military to assist in firefighting. WHY DOES THE AMAZON MATTER? The Amazon - 60% of which is in Brazil - is the world's largest tropical rainforest.