Record leap in CO2 fuels fears of accelerating global heating | Greenhouse gas emissions

Carbon dioxide levels in the atmosphere have soared from a record high in 2024 to a new high, according to UN data, worsening the climate crisis that is already costing lives and livelihoods across the world.

Scientists worry that natural land and oceans are ‘sinking’ and removing CO₂ air is weakening due to global warming, which could form a vicious cycle and cause temperatures to rise even faster.

The global average concentration of the gas jumped 3.5 parts per million to 424 ppm in 2024, the largest increase since modern measurements began in 1957, according to the World Meteorological Organization report.

Several factors contributed to the increase in CO₂including another year of relentless fossil fuel consumption despite countries around the world pledging in 2023 to “move away” from coal, oil and gas. Another factor has been an increase in wildfires in conditions made hotter and drier by global warming. Wildfire emissions in the Americas reached historic levels in 2024, which was the hottest year on record.

However, scientists worry about a third factor: the possibility that the planet’s carbon sinks will begin to fail. About half of all CO₂ Each year, emissions are removed from the atmosphere by being dissolved in the ocean or absorbed by the growth of trees and plants. But the oceans are warming and can therefore absorb less CO₂ while on land, hotter, drier conditions and more wildfires mean less plant growth.

Carbon sinks were already known to be less effective during El Niño years, such as 2023 and 2024, when changes in Pacific winds and ocean currents cause global air temperatures to rise. But human-caused global warming has already raised average global temperatures by around 1.3C and researchers, who have recorded an “unprecedented failure of the Earth’s well” in 2023 and 2024, fear this could weaken the wells.

Oksana Tarasova, WMO Principal Scientist, said: “There are concerns that terrestrial and oceanic CO₂ wells become less efficient, which will increase the amount of CO₂ which remains in the atmosphere, thus accelerating global warming. Sustained and strengthened greenhouse gas monitoring is essential to understanding these loops.

Increase in CO₂ Emissions not only impact the global climate today, but will do so for hundreds of years due to the gas’s long lifespan in the atmosphere, the WMO says.

Ko Barrett, Deputy Secretary-General of WMO, said: “Heat trapped by CO₂ and other greenhouse gases fuel our climate and lead to more extreme weather. Reducing emissions is therefore essential not only for our climate, but also for our economic security and the well-being of our communities.

Atmospheric concentrations of methane and nitrous oxide – the second and third greenhouse gases linked to human activities – also reached record levels in 2024.

About 40% of methane emissions come from natural sources. But scientists worry that global warming could lead to increased methane production in wetlands, another potential feedback loop. The rest comes from the exploitation of fossil fuels; livestock such as cattle; rotting waste in landfills; and rice fields. Human-caused nitrous oxide emissions include those from the overuse of fertilizers by farmers and some industrial processes.

The WMO released its annual greenhouse gas bulletin a month before Cop30, the United Nations climate change summit in Belém, Brazil, where representatives of the world’s countries will try to step up climate action. The data comes from a network of 500 monitoring stations around the world.