New climate change study: 1.5-degree target in danger – CO₂ budget could soon be used up

130 billion tons of carbon dioxide (CO₂). This is the remaining amount of CO₂ that can still be emitted to meet the 1.5-degree target. It can't be any higher, otherwise the climate crisis would further worsen. But apparently there isn't much left of the CO₂ budget, at least that's what the "Indicators of Global Climate Change" study suggests.

The new version of the study was published Thursday in the journal Earth System Science Data. Since 2023, international scientists have been examining the most important climate change indicators annually. This time, it was found that, with current historically high CO₂ emissions, the budget could be exhausted in just over three years. The budget for 1.6 or 1.7 degrees Celsius would be exhausted within nine years.

"The window of opportunity to maintain the 1.5-degree limit is rapidly closing," says Joeri Rogelj, study author and research director at the Grantham Institute of Imperial College London. Last year, the 1.5-degree mark was already exceeded for the first time: Compared to pre-industrial levels, the global average temperature rose by 1.52 degrees Celsius. Of this, 1.36 degrees can be clearly attributed to human influence, the study states.

Even if exceeding the 1.5-degree mark does not mean the end of the 1.5-degree target, the temperature trend is alarmingly clear – and will be further accelerated by greenhouse gas emissions.

Europe has experienced an unprecedented year of weather extremes: 2024 was marked by record heat, floods, and melting glaciers. But the new report on the state of the climate in Europe also contains two pieces of positive news.

Over the past ten years, an average of around 53 billion tons of CO₂ were released annually, the study authors write. A large portion of this comes from the combustion of fossil fuels such as oil and natural gas, but also from deforestation. When trees are felled, the CO₂ they have stored is released and can accumulate in the atmosphere. Added to this were emissions from aviation in 2024, which returned to pre-pandemic levels after the quiet years of the coronavirus pandemic.

Experts therefore estimate that CO₂ emissions will reach almost 42 gigatons of CO₂ in 2024, about two percent more than in 2023. Precise data is still pending. The greenhouse gases methane (which is even more harmful to the climate than CO₂) and nitrous oxide are also driving the climate crisis. According to the study, the global average near-surface concentration of methane has increased by 3.4 percent and that of nitrous oxide by 1.7 percent since 2019.

"Emissions over the next decade will determine how quickly the 1.5-degree mark is reached," says Rogelj. "To achieve the climate goals of the Paris Agreement, emissions must be reduced rapidly." The EU, for example, has set itself the goal of achieving net-zero emissions by 2050 – that is, reducing greenhouse gas emissions as much as possible and neutralizing any remaining emissions. According to the EU Commission, the first milestone (EU-wide greenhouse gas emissions are to be reduced by 55 percent by 2030 compared to 1990 levels) could already be achieved, albeit only just.

"If we don't take decisive action against emissions in the coming years, current and future generations will face increasing and dramatic impacts of climate change," warns William Lamb of the Potsdam Institute for Climate Impact Research, who also participated in the study. He and his colleagues have already observed initial effects – for example, in sea levels.

Between 2019 and 2024, global mean sea level rose by about 26 mm. This is more than double the long-term rise of 1.8 mm per year since the turn of the century. Thus, the total sea level rise since 1900 amounts to about 228 mm.

A seemingly small number, admits Aimée Slangen, research director at the Royal Netherlands Institute for Sea Research. But it has "enormous impacts on low-lying coastal areas." "It intensifies storm surges and leads to greater coastal erosion, which poses a threat to people and coastal ecosystems." Around 2.2 billion people, almost a third of the world's population, live within 50 kilometers of the coast.

"What's worrying is that sea level rise in response to climate change is occurring relatively slowly," says Slangen. This means that even if greenhouse gas emissions were to suddenly drop sharply, the oceans wouldn't immediately notice the effects. They would initially continue to warm because they react with a delay to changes in the atmosphere. "This means we can expect further increases in the coming years and decades," warns the marine researcher.