This story was originally published on The Conversation and appears here under a Creative Commons license. Bornean orangutans are one of three orangutan species, all critically endangered. They thrive in carbon-rich peat swamp forests on the Indonesian island of Borneo. These habitats are also the sites of massive wildfires. Indonesian wildfires in 2015 caused some of the worst fire-driven air pollution ever recorded. The fires were driven by an El Niño climatic cycle, which caused especially dry weather in the region. Compared to other wildfires, peatland fires smolder underground and…