As they have every dry season for the last 20 years, once lush tropical peatlands in Indonesia smoldered for weeks this year, leaving the region cloaked in a thick, carbon-rich haze.

The rainy season arrived at the end of October, squelching the flames. Even so, Jack Rieley, a peatland ecologist at the University of Nottingham in the United Kingdom, had no time to sigh in relief. With the rains come the floods.