Agence France-PresseLevels of the most important greenhouse gases in our atmosphere rose faster than ever recorded last year, scientists say, leaving a major global climate target hanging by a thread.
Carbon dioxide (CO2) concentrations are now more than 50% higher than they were before humans started burning large amounts of fossil fuels.
Last year, fossil fuel emissions reached record levels, while the natural world struggled to absorb a significant amount of carbon dioxide due to factors including bushfires and drought, causing more to accumulate in the atmosphere.
The Met Office says the rapid increase in carbon dioxide is “inconsistent” with an international pledge to try to limit global warming to 1.5C above pre-industrial levels.
This was the ambitious goal agreed by about 200 countries at a historic UN meeting in Paris in 2015, in the hope of avoiding some of the worst impacts of climate change.
Last week, this was confirmed 2024 was the hottest year on recordthe first calendar year in which average annual temperatures were more than 1.5°C above pre-industrial levels.
This does not break the Paris target, which refers to a longer-term average over decades, but continuing increases in atmospheric carbon dioxide are already pushing the world to do so.
“Limiting global warming to 1.5°C would require a slowdown in the rise of carbon dioxide, but in fact the opposite is happening,” says Richard Bates of the Met Office.
There is no doubt that the long-term increase in carbon dioxide is due to human activities, especially through burning coal, oil and gas and cutting down forests.
Records of Earth's climate in the distant past from ice cores and marine sediments show that carbon dioxide levels are currently at their highest levels in at least two million years, according to the United Nations.
But the rise varies from year to year, thanks to differences in how the natural world absorbs carbon, as well as fluctuations in human emissions.
Last year, carbon dioxide emissions from fossil fuels reached new highs, according to preliminary data from the Global Carbon Project team.
There were also traces The natural phenomenon of El Niño – Surface waters in the eastern tropical Pacific Ocean become unusually warm, affecting weather patterns.
Nearly half of humanity's carbon dioxide emissions have been absorbed by the natural world, for example through additional plant growth and more of the gas being dissolved in the oceans.
But this extra blast of heat from El Niño on the back of climate change means that Earth's natural carbon sinks are not absorbing as much carbon dioxide as last year.
Raging forest fires, including in areas not normally affected by El Niño, have also released additional amounts of carbon dioxide.
“Even without a boost from last year's El Niño, rising CO2 from fossil fuel burning and deforestation would now exceed the IPCC's 1.5°C scenarios,” says Professor Bates. .
These factors mean that carbon dioxide levels increased between 2023 and 2024 by about 3.6 parts per million molecules of air to a new level of more than 424 parts per million.
This is a record annual increase since atmospheric measurements were first made at the remote Mauna Loa research station in Hawaii in 1958. The station is located high on the side of a volcano in the Pacific Ocean, and its remote location away from major sources of pollution makes it ideally suited. To monitor global carbon dioxide levels.
“These latest results confirm that we are moving into uncharted territory faster than ever before as the rise continues to accelerate,” says Professor Ralph Keeling, who leads the measurement program at the Scripps Institution of Oceanography in the US.
Agence France-PresseThis record increase raises concerns that the natural world may become less able to absorb greenhouse gases in the long term.
The Arctic tundra is turning into a global source of carbon dioxide, thanks to rising temperatures and more frequent fires, according to US science group NOAA.
the The ability of the Amazon rainforest to absorb carbon dioxide They are also exposed to drought, forest fires and deliberate deforestation.
Professor Bates told the BBC: “It's an open question, but it's something we need to monitor closely and look at very carefully.”
The Met Office expects the increase in carbon dioxide concentration in 2025 to be less severe than in 2024, but is still far from on track to meet the 1.5°C target.
La Niña conditions — where surface waters in the eastern tropical Pacific are cooler than normal — have replaced El Niño, which tends to allow the natural world to absorb more carbon dioxide.
“Although there may be a temporary respite with slightly cooler temperatures, warming will resume because carbon dioxide is still accumulating in the atmosphere,” Professor Bates says.
