Atmospheric carbon dioxide (CO₂) levels climbed to unprecedented levels in 2024, rising by the largest annual margin ever recorded and locking the planet into more long-term warming and extreme weather, the World Meteorological Organization (WMO) reported.
In its latest Greenhouse Gas Bulletin, the UN weather agency said the surge was driven by continued human emissions, widespread wildfires, and a weakening ability of land and ocean “sinks” to absorb carbon — a pattern that “threatens to be a vicious climate cycle.”
CO₂ levels tripled since the 1960s
The WMO said the rate of CO₂ growth has tripled over the past six decades, from an annual average increase of 0.8 parts per million (ppm) in the 1960s to 2.4 ppm per year between 2011 and 2020.
Between 2023 and 2024, global CO₂ concentrations spiked by 3.5 ppm — the largest jump since monitoring began in 1957 — reaching an average of 423.9 ppm. When the WMO first published the bulletin in 2004, the concentration stood at 377.1 ppm.
About half of all CO₂ released each year remains in the atmosphere, while the rest is absorbed by forests, soils, and oceans. But those natural storage systems are weakening, the report warned, as rising temperatures reduce the ocean’s ability to absorb carbon and prolonged droughts disrupt land-based sinks.
The record growth in 2024, the WMO added, was likely intensified by wildfire emissions and a decline in carbon uptake during what became the warmest year on record, worsened by a strong El Niño pattern. Drier conditions and widespread fires — particularly in the Amazon and southern Africa — further reduced the efficiency of land carbon sinks.
‘Turbo-charging our climate’
“The heat trapped by CO₂ and other greenhouse gases is turbo-charging our climate and leading to more extreme weather,” said Ko Barrett, WMO Deputy Secretary-General.
“Reducing emissions is therefore essential not just for our climate but also for our economic security and community well-being,” Barrett added.
Methane and nitrous oxide also hit record highs
The report noted that methane and nitrous oxide — the second and third most significant long-lived greenhouse gases — also reached record levels in 2024.
Global methane concentrations rose to 1,942 parts per billion (ppb), 166 percent above pre-industrial levels, while nitrous oxide climbed to 338 ppb, a 25 percent increase.
Methane is responsible for about 16 percent of the warming effect caused by long-lived greenhouse gases, with roughly 60 percent of its emissions coming from human activities such as livestock, rice cultivation, fossil fuel extraction, and waste.
Nitrous oxide, meanwhile, comes from sources including fertilizer use, industrial processes, and biomass burning.
“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 senior scientific officer.
Tarasova said the Sustained and strengthened greenhouse gas monitoring “is critical to understanding these loops.”
Call for stronger monitoring ahead of COP30
The WMO issued the report ahead of the UN Climate Change Conference (COP30) in Belém, Brazil, which opens in November.
The agency said the findings were intended to guide policymakers as they seek to strengthen climate action.
“Sustaining and expanding greenhouse gas monitoring are critical to support such efforts,” added Tarasova, who coordinates the WMO’s flagship scientific bulletin, now in its 21st issue.
WMO reports record rise in CO₂ levels in 2024, warning weakened natural sinks could accelerate global warming.
