World’s Forest Carbon Sink Shrank to its Lowest Point in at Least 2 Decades, Due to Fires and Persistent Deforestation

Forests have been quietly cooling the planet for decades, but their role is increasingly under threat.

Forests have historically acted as a reliable planetary thermostat. They regulate Earth’s temperature by removing carbon dioxide (CO2) from the atmosphere and locking it in trees, roots and soil — carbon that is emitted if trees are cut down. In a typical year, forests and other vegetation absorb roughly 30% of the carbon that humans emit from burning fossil fuels — a vital climate service performed at virtually no cost by trees around the world, from tropical rainforests to temperate and boreal forests.

But the past several years have been anything but typical.

New analysis of data from WRI’s Global Forest Watch (GFW) and Land & Carbon Lab reveals that extreme fires caused forests to absorb far less carbon than usual in 2023 and 2024, weakening their cooling effect. During those years, forests absorbed only a quarter of the carbon dioxide they do in an average year. 2023 marked the lowest “forest carbon sink” in over two decades when considering the loss of trees’ stored carbon and greenhouse gases caused by burning.

This recent sharp drop is also part of a longer-term decline, where the margin between forest emissions and carbon removals appears to be narrowing. With emissions from deforestation and other forest disturbances rising, the world’s forests risk shifting from a carbon sink to a carbon source.