Levels of heat-trapping carbon dioxide in Earth’s atmosphere surged by the largest margin ever recorded last year.
The finding in a new report from the World Meteorological Organization means the planet remains on track for more long-term warming, as natural systems struggle to keep up with emissions.
The WMO’s Greenhouse Gas Bulletin pins the spike on three key drivers: continued emissions from fossil fuels, increased CO₂ released by wildfires, and weakening carbon sinks like forests and oceans. These sinks normally absorb a large portion of human-made carbon emissions, but in 2024 they fell short and set the stage for a dangerous feedback loop.
The story is in the numbers: Since the 1960s, the pace of CO₂ buildup has tripled: from 0.8 parts per million annually to 2.4 ppm per year in the 2010s. Between 2023 and 2024, however, levels spiked by 3.5 ppm – the sharpest increase recorded since modern monitoring began in 1957.
"The heat trapped by CO2 and other greenhouse gases is turbo-charging our climate and leading to more extreme weather," said WMO Deputy Secretary-General Ko Barrett. "Reducing emissions is therefore essential not just for our climate but also for our economic security and community well-being."
Concentrations of methane and nitrous oxide _ the second and third most important long-lived greenhouse gases related to human activities _ have also risen to record levels.
Since the WMO began publishing its bulletin in 2004, CO₂ pollution levels have climbed steadily. Back then, the global average was 377.1 ppm. In 2024, it hit 423.9 ppm _ a rise of nearly 47 ppm in just two decades.

Natural climate controls are faltering
Roughly half of all CO₂ emissions each year stay in the atmosphere. The rest is temporarily absorbed by land and ocean “sinks.”
But researchers say this natural buffering system is weakening; warmer oceans take up less CO₂, and land-based sinks are increasingly disrupted by drought and ecosystem stress.
Last year _ the hottest year on record _ these systems faltered. A strong El Niño amplified global temperatures, pushing oceans and forests past their capacity to absorb carbon. At the same time, wildfires raged across large sections of the globe, pumping massive amounts noxious gases into the atmosphere and further degrading land-based carbon sinks.
Researchers say this formula for disaster – increased emissions, fewer sinks, and extreme heat – likely explains the record-breaking 3.5 ppm jump in CO₂ from 2023 to 2024.
"There is concern that terrestrial and ocean CO2 sinks are becoming less effective, which will increase the amount of CO2 that stays in the atmosphere, thereby accelerating global warming," said Oksana Tarasova, a WMO researcher. "Sustained and strengthened greenhouse gas monitoring is critical to understanding these loops."
The consequences of today’s emissions will likely haunt humankind. Carbon dioxide lingers in the atmosphere for centuries, WMO emphasized, and the damage we’re doing today will shape the climate for generations.
WMO’s analysis draws on data from monitoring stations worldwide. It shows a stark and steady rise in CO₂ from 1984 to 2024, with each year stacking more carbon into the atmosphere.
While CO₂ gets most of the attention, it’s not the only problem. Methane and nitrous oxide are also rising fast.
Methane is responsible for about 16% of the warming caused by long-lived greenhouse gases. Though it remains only about nine years in the atmosphere, it traps heat far more effectively than CO₂.
In 2024, methane levels hit 1,942 parts per billion, some 166% higher than pre-industrial levels. Around 60% of methane emissions come from human activities like fossil fuel use, agriculture, and landfills. The remaining 40% comes from natural sources like wetlands, which are themselves being altered by climate change.
Nitrous oxide, the third major long-lived greenhouse gas, is also on the rise. Its main sources include fertilizer use, biomass burning, and industrial processes. In 2024, its global concentration reached 338 ppb, a 25% increase since pre-industrial times.
WMO published the bulletin to provide authoritative scientific information for COP 30, the U.N. Climate Change summit, meeting next month in Belém, Brazil.