Planet-warming gas levels to rise higher than ever in 2024

Scientists say levels of the most important planet-warming gas in our atmosphere have risen faster than ever recorded last year, putting a key global climate goal in limbo.

The concentration of carbon dioxide (CO2) is now more than 50% of what it was before humans began burning fossil fuels in large quantities.

Last year, fossil fuel emissions hit record highs while the natural world struggled to absorb more CO2, causing more to accumulate in the atmosphere due to factors including wildfires and drought.

The Met Office says the rapid rise in CO2 is “inconsistent” with an international pledge to limit global warming to 1.5C above pre-industrial levels.

Nearly 200 countries agreed to this ambitious goal at a historic UN meeting in Paris in 2015, in the hope of avoiding some of the worst impacts of climate change.

This was confirmed last week 2024 was the hottest year on recordand the first calendar year in which the annual average temperature was 1.5C above pre-industrial levels.

It did not break the Paris target, which refers to a long-term average over decades, but the continued increase in atmospheric CO2 effectively prompted the world to do so.

“To limit global warming to 1.5C CO2 rise would have to be slowed, but in fact the opposite is happening,” says Richard Bates of the Met Office.

The long-term CO2 increase is undeniably due to human activities, primarily burning coal, oil and gas and cutting down forests.

According to the United Nations, records of Earth’s climate in the distant past obtained from ice cores and marine sediments show that CO2 levels are currently at their highest in at least two million years.

But the increase varies from year to year, due to differences in the way the natural world absorbs carbon as well as fluctuations in humanity’s emissions.

CO2 emissions from fossil fuels reached new highs last year, according to preliminary data from the Global Carbon Project team.

also had an impact natural El Nino phenomenon – Where surface waters in the eastern tropical Pacific Ocean become unusually warm, affecting weather patterns.

The natural world has absorbed about half of humanity’s CO2 emissions, for example through additional plant growth and more of the gas dissolving in the oceans.

But that extra burst of heat from El Nino against the backdrop of climate change means that natural carbon sinks on land took up no more CO2 than last year.

Large-scale wildfires, including in areas not normally affected by El Niño, also released additional CO2.

“Even without the stimulus of last year’s El Niño, CO2 increases driven by fossil fuel burning and deforestation would now exceed the (UN climate body’s) IPCC’s 1.5C scenarios,” says Professor Bates.

These factors mean CO2 levels could rise by about 3.6 parts per million (ppm) of air molecules to a new high of more than 424 ppm between 2023 and 2024.

This is a record annual increase since atmospheric measurements were first taken at Hawaii’s remote Mauna Loa Research Station in 1958. Located on the edge of a volcano in the Pacific Ocean, the station’s remote location away from major pollution sources makes it ideally suited for monitoring global CO2 levels.

Professor Ralph Keeling, who leads the measurement program at the Scripps Institution of Oceanography in the US, says: “These latest results confirm that we are moving into uncharted territory faster than ever before as the growth continues to accelerate “

The record increase has raised concerns that the natural world may become less able to absorb planet-warming gases in the long run.

According to US science group NOAA, the Arctic tundra is turning into an overall source of CO2 due to warming and frequent fires.

The ability of the Amazon rainforest to absorb CO2 It is also being affected by drought, forest fires and deliberate deforestation.

“It’s an open question, but it’s something we need to keep a close eye on and look at very carefully,” Professor Bates tells the BBC.

The Met Office estimates that the increase in CO2 concentrations in 2025 will be less than in 2024, but still a long way from meeting the 1.5C target.

La Nina conditions – where surface waters in the eastern tropical Pacific Ocean are cooler than normal – have replaced El Nino, allowing the natural world to take in more CO2.

“Although there may be temporary relief with slightly cooler temperatures, warming will resume as CO2 is still building up in the atmosphere,” says Professor Bates.