Ecosystem carbon loss: increasing risk of ecosystem carbon losses that could substantially raise the atmospheric carbon dioxide level. Measurements have detected emissions of carbon from boreal, temperate and tropical ecosystems in places where increases in wildfire and tree mortality have been attributed to anthropogenic climate change, at GMST increases of 0.6°C-0.9°C above the pre-industrial period. Many factors govern the carbon balance of ecosystems, so changes have not been attributed to climate change. Tropical forests and Arctic permafrost contain the highest ecosystem stocks of above- and below-ground carbon, respectively. Due to deforestation and forest degradation, primary tropical forests currently emit more carbon to the atmosphere than they remove. Wildfires in the Arctic are contributing to permafrost thaw and soil carbon release. An emissions scenario of 2ºC increase could thaw ~15% of permafrost area and emit 20-100 GtC by 2100. Under emissions scenarios of 4℃ global temperature increase, models project possible tipping points of conversion of half the Amazon rainforest to grassland and thawing of Arctic permafrost that could release 11-200 GtC which could substantially exacerbate climate change .
IPCC
Climate Change 2022: Impacts, Adaptation and Vulnerability
IPCC Report