Forests worldwide are crucial to our fight against climate change but researchers have found that 10 UNESCO World Heritage forests are now emitting more carbon than they absorb. How did the world’s most protected forests get to this stage? Can the damage be reversed to restore them as carbon sinks? What is the impact of national efforts and international commitments like those made at COP26? Jaime Ho speaks to Tales Carvalho Resende, project officer at the Natural Heritage Unit of the UNESCO World Heritage Centre.