Scientists have 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 finalised in South Korea.The natural processes by which forests suck in and store carbon help reduce levels of planet-warming carbon dioxide in the atmosphere – and forests also underpin key parts of the world’s economy, the scientists said.”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 emphasising how the earth’s climate depends on forests.The statement, signed by researchers mainly from the United States, Brazil and Europe, highlighted the importance of protecting and maintaining healthy forests.The flagship report from the Intergovernmental Panel on Climate Change, due to be published on Monday, will outline ways of limiting global temperature rise to 1.5 degrees Celsius, compared with pre-industrial times, the most ambitious goal in the Paris climate pact.One key route is to protect virgin forests, restore those that have suffered logging, fires or other harm, and expand the amount of land covered by trees, the report is expected to…