For developing nations, which often host vulnerable ecosystems and communities yet bear the least historic responsibility for emissions, the risks are particularly acute. The decreasing reliability of carbon sinks may mean fewer “buffers” against ongoing climate change.
A dramatic leap in atmospheric carbon dioxide (CO₂) levels in 2024 has signalled a possible intensification of the global climate crisis, according to a new report from the World Meteorological Organization (WMO). The annual rise of 3.5 parts per million (ppm) in CO₂ – the largest single-year jump since systematic measurements began in 1957 – has triggered concerns of a “vicious climate cycle” in which the Earth’s natural carbon-absorbing systems begin to falter.
The findings, published in the WMO’s latest editions of its Greenhouse Gas Bulletin, lay bare how continued fossil fuel emissions and wildfire events have combined with a weakening of carbon sinks – the planet’s forests, soils and oceans – to drive the unprecedented CO₂ spike.
A Record-Breaking Rise
From 2023 to 2024, global average CO₂ concentrations rose by approximately 3.5 ppm – up from a decade average of ~2.4 ppm per year during 2011–2020. In absolute terms, CO₂ levels reached around 423.9 ppm in 2024, placing the planet well above pre-industrial concentrations of ~280 ppm.
“This rapid increase not only locks in further long-term temperature rise, but also signals that natural systems are under extreme stress,” said Ko Barrett, Deputy Secretary-General of the WMO. “The heat trapped by CO₂ and other greenhouse gases is turbo-charging our climate and leading to more extreme weather.”
Why the Surge?
The WMO points to three key factors:
- Continued human emissions from fossil fuels, cement and land use changes remain high.
- Wildfire emissions – particularly in regions affected by drought and heat – have surged, releasing large quantities of carbon into the atmosphere.
- Reduced effectiveness of carbon sinks. Warmer oceans absorb less CO₂ and stressed ecosystems (e.g., drought-hit forests) are absorbing less than before.
WMO senior scientific officer Oksana Tarasova warned: “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.”
The report describes this interplay of emissions and weaker sinks as a potential “vicious climate cycle”. As the planet warms, ecosystems that once removed CO₂ become less efficient – causing more CO₂ to accumulate, which in turn accelerates warming further.
The WMO flagged that about half of human-emitted CO₂ each year is normally absorbed by land and ocean sinks; but the decline in their uptake threatens to shift more of that carbon into the atmosphere.
Broader Greenhouse Gas Context
CO₂ is not the only concern. The WMO’s bulletin indicates that levels of methane (CH₄) and nitrous oxide (N₂O) have also reached record highs – adding to the overall greenhouse-gas burden and warming potential.
Methane, for example, contributes significantly to radiative forcing – the trapped heat energy driving global temperature rise – while nitrous oxide is linked to agriculture and industrial processes. The combined effect strengthens the impetus for urgent action.
The scale of the rise severely hampers hopes of meeting the 1.5 °C target set under the Paris Agreement. Scientists say that once atmospheric concentrations push beyond certain thresholds and sinks degrade further, the margin for limiting global warming shrinks dramatically.
The WMO report arrives just weeks before the COP 30 climate summit in Belém, Brazil, underscoring the urgency of deep emission cuts, strengthened monitoring and robust finance for mitigation and adaptation.
What’s at Stake?
A surge at this level can translate into more frequent and intense weather events – heatwaves, wildfires, droughts, storms – as well as long-term shifts in ecosystems, agriculture and sea-level trends. The WMO warns that CO₂ emitted today will affect the climate for hundreds of years.
For developing nations, which often host vulnerable ecosystems and communities yet bear the least historic responsibility for emissions, the risks are particularly acute. The decreasing reliability of carbon sinks may mean fewer “buffers” against ongoing climate change.
The WMO emphasizes several key responses:
- Rapid and deep reductions in CO₂ and other greenhouse-gas emissions, especially from fossil fuels and land-use change.
- Restoration and protection of natural carbon sinks – forests, wetlands, soils – and improved understanding of how they are changing.
- Strengthened global monitoring systems, to track greenhouse-gas concentrations, sinks and feedback loops more precisely.
- Scaled climate finance, so that vulnerable countries can adapt and transition to low-carbon pathways.
