Scientists from around the world called for stepped-up efforts to use forests to keep global warming to the lowest limit agreed by governments in 2015, as a key report on how to meet that goal is finalized in South Korea this week. “Forests really are the unsung hero of our struggle to address climate change,” said Deborah Lawrence, a University of Virginia professor and one of 40 scientists who backed a statement emphasizing how the Earth’s climate depends on forests.