Levels of carbon dioxide in the atmosphere soared by a record amount in 2024 to hit another high, UN data shows, deepening the climate crisis that is already taking lives and livelihoods across the world.

Scientists are worried that the natural land and ocean “sinks” that remove CO2 from the air are weakening as a result of global heating, which could form a vicious circle and drive temperatures up even faster. The global average concentration of the gas surged by 3.5 parts per million to 424ppm in 2024, the largest increase since modern measurements started in 1957, according to the report by the World Meteorological Organization.

Several factors contributed to the leap in CO2, including another year of unrelenting fossil fuel burning despite a pledge by the world’s countries in 2023 to “transition away” from coal, oil and gas. Another factor was an upsurge in wildfires in conditions made hotter and drier by global heating. Wildfire emissions in the Americas reached historic levels in 2024, which was the hottest year yet recorded.