British Columbia in Canada, during the 2023 wildfire seasonDavid J. Mitchell/Shutterstock
Extreme heat, drought and wildfires caused forests and other land ecosystems to emit almost as much carbon dioxide as they removed from the atmosphere in 2023, nearly canceling out a major natural sink of the greenhouse gas.

Researchers say the temporary decline of this sink – which usually removes about a quarter of our annual CO2 emissions from the atmosphere – bodes ill for how these ecosystems will respond to future climate change.
“It’s pretty grim,” says…