evidence: In 2021, for example, Russia saw 5.4 million hectares of fire-related tree cover loss, the most recorded for that country in the last 23 years. This was due in part to prolonged heatwaves that would have been practically impossible without human-induced climate change. [...] In addition to climate and land-use changes, wildfire risk in the tropics is further fueled by El Niño events. These natural climate cycles recur every 2-7 years, causing high temperatures and below-average rainfall in certain parts of the world. During the 2015-2016 El Niño season, tree cover loss due to fires increased 10-fold in the tropical rainforests of Southeast Asia and Latin America. The strongest El Niño event since 2015-2016 emerged in June 2023 and officially ended in May 2024. [...] Similar to boreal forests, increasing tree cover loss due to fires in the tropics is causing higher carbon emissions. Previous studies found that in some years, forest fires accounted for more than half of all carbon emissions in the Brazilian Amazon. This suggests the Amazon basin may be nearing or already at a tipping point for turning into a net carbon source.