UN warns of vicious circle CO2 concentration in the atmosphere is rising drastically
In 2024, theconcentration of CO2 in the atmosphere has risen more than ever before. What this means for our climate - and why the WMO speaks of a vicious circle.
15.10.2025, 15:57
15.10.2025, 16:02
dpa
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- The concentration ofCO2 in the atmosphere rose by 3.5 ppm last year - the highest annual increase since measurements began in 1957.
- In addition to man-made greenhouse gases, forest and bush fires are also responsible for the increase in concentration.
- At the same time, the absorption capacity ofCO2 in forests and oceans is decreasing - itself a consequence of climate change. The WMO speaks of an impending vicious circle.
- The problem was exacerbated last year by the natural weather phenomenon El Niño, which occurs every few years.
- Theconcentration of CO2 has an impact on the climate for centuries because the gas remains there for so long.
The concentration of climate-damaging carbon dioxide (CO2) in the atmosphere rose dramatically in 2024 - more than at any time since modern measurements began in 1957. The annual increase has tripled since the 1960s, the World Meteorological Organization (WMO) reported in its annual Greenhouse Gas Bulletin. The greenhouse gases methane (CH4) and nitrous oxide (N2O) have also risen to record levels.
In the 1960s, the annualincrease in CO2 was 0.8 ppm (parts per million). Between 2011 and 2020, it averaged 2.4 ppm per year. From 2023 to 2024, the concentration rose by 3.5 ppm. TheCO2 concentration in the atmosphere thus reached 423.9 ppm in 2024.
TheCO2 concentration has an impact on the climate for centuries because the gas remains there for so long. Experts estimate that around 15 to 40 percent of it will still be in the atmosphere after 1000 years.CO2 is produced when fossil fuels such as coal, oil and natural gas are burned - for example in electricity and heat generation, in transportation, in industrial production and in households.
WMO speaks of a "vicious circle"
The massive increase in greenhouse gas concentrations in the atmosphere is cause for "serious concern", explained the WMO. In addition to man-made greenhouse gases, forest and bush fires are also causing the increase in concentrations. At the same time, the absorption capacity ofCO2 in forests and oceans is decreasing - this itself is a consequence of climate change. The WMO speaks of an impending vicious circle.
The problem was exacerbated last year by the natural weather phenomenon El Niño, which occurs every few years and causes more droughts in South America and southern Africa, for example, as well as more forest fires. During droughts, ecosystems can absorb lessCO2.
2024 was the warmest year since industrialization (around 1750), with a global average temperature a good 1.55 degrees above pre-industrial levels. The oceans were also warmer than ever before last year, both on the surface and down to a depth of 2,000 meters.
Bad news for the Paris climate target
Around half of thetotal amount of CO2 emitted remains in the atmosphere, while the other half is absorbed by ecosystems on land and in the oceans. "As global temperatures rise, the oceans absorb lessCO2, as solubility decreases at higher temperatures, while land sinks are affected in many ways, including the risk of prolonged droughts," the WMO emphasizes.
Greenhouse gases must be drastically reduced as a matter of urgency, it continues. Otherwise, the organization believes that the Paris climate goal of limiting global warming to well below two degrees and, if possible, 1.5 degrees above pre-industrial levels is at risk.
Although the increase in 2024 was already above 1.5 degrees, the climate target is not about individual annual values. Rather, an increase over a longer period of at least ten years is relevant.
The WMO data that has now been published provides information on the concentration of greenhouse gases in the atmosphere one month before the start of the next UN Climate Change Conference, which begins on November 10 in Bélem, Brazil. A second UN report, to be published in November, will look at the changes that have led to the increased emissions.
