2024 first to pass 1.5C warming limit

The planet has taken a big step toward warming by more than 1.5C, new data shows, although world leaders promised a decade ago they would try to avoid that.

Europe’s Copernicus climate service, a leading global data provider, said Friday that 2024 was the first calendar year to cross the symbolic threshold, as well as the world’s hottest on record.

This does not mean that the international target of 1.5°C has been exceeded, as it is a long-term average over decades, but it does bring us closer to this target as fossil fuel emissions continue. to warm the atmosphere.

Last week, UN chief António Guterres called the recent string of temperature records a “climate breakdown.”

“We must get off this path to ruin – and we have no time to lose,” he said in his New Year’s message, calling on countries to reduce their greenhouse gas emissions. greenhouse in 2025.

According to Copernicus data, global average temperatures for 2024 were about 1.6°C higher than in the pre-industrial period – the period before humans began burning large quantities of fossil fuels.

This breaks the record set in 2023 by just over 0.1°C, meaning the last 10 years are now the 10 warmest years on record.

The Met Office, NASA and other climate groups are expected to release their own data later on Friday. Everyone should agree that 2024 was the hottest on record, although the precise numbers vary slightly.

Last year’s heat was mainly due to human emissions of greenhouse gases, such as carbon dioxide, which were still at record levels.

Natural weather phenomena such as El Niño, where the surface waters of the eastern tropical Pacific Ocean become unusually warm, played a lesser role.

“The concentration of greenhouse gases in the atmosphere is by far the greatest contributor to the impact on our climate,” Samantha Burgess, deputy director of Copernicus, told the BBC.

The 1.5°C figure has become a powerful symbol in international climate negotiations since it was agreed in Paris in 2015, with many of the most vulnerable countries seeing it as a matter of survival.

Climate change risks, such as intense heatwaves, sea level rise and wildlife loss, would be much higher at 2°C of warming than at 1.5°C, according to a landmark 2018 UN report.

However, the world is getting closer and closer to the 1.5°C mark.

“It is difficult to predict when exactly we will cross the 1.5°C threshold in the long term, but we are obviously very close to it now,” says Myles Allen of the Department of Physics at the University of Oxford and author of the report. of the UN.

The current trajectory would likely see the world surpass the 1.5°C mark of long-term warming by the early 2030s. This would be politically important, but it would not mean the end of climate action.

“It’s not like 1.49°C is a good thing, and 1.51°C is the apocalypse: every tenth of a degree counts and climate impacts get progressively worse as we get warmer,” explains Zeke Hausfather, climatologist at Berkeley Earth, a research group in the United States.

Even fractions of a degree of global warming can lead to more frequent and intense extreme weather, such as heat waves and heavy precipitation.

In 2024, the world saw scorching temperatures in West Africaprolonged drought in parts of South Americaintense precipitation in central Europe and some particularly severe tropical storms hitting North America and South Asia.

These events were just some of those made more intense by climate change over the past year, according to the World Weather Attribution group.

Even this week, as the new numbers are released, Los Angeles has been overwhelmed by destructive wildfires fueled by high winds and a lack of rain.

Although many factors contributed to this week’s events, experts say fire-prone conditions in California are becoming more likely in a warming world.

It’s not just air temperatures that have set new benchmarks in 2024. global sea surface also hit new daily recordwhile the total amount of humidity in the atmosphere has reached record levels.

That the world is breaking new records is no surprise: 2024 has always been expected to be hot, due to the effect of the El Niño climatic phenomenon – which finished around April last year – in addition to human-caused warming.

But the margin of several records in recent years was less expected, with some scientists concerned that it could represent an acceleration of warming.

“I think it’s safe to say that the temperatures of 2023 and 2024 surprised most climate scientists – we didn’t expect to see a year above 1.5°C so soon,” says Dr Hausfather.

“Since 2023, we have experienced an additional warming of around 0.2°C that we cannot fully explain, in addition to what we expected from climate change and El Niño,” recognizes climate physicist Helge Gößling at the Alfred Wegener Institute in Germany. .

Various theories have been suggested to explain this “extra” heat, such as an apparent reduction in low-level cloud cover that tends to cool the planet, and prolonged oceanic warmth after the end of El Niño.

“The question is whether this acceleration is a persistent phenomenon linked to human activities, which means that we will experience greater warming in the future, or whether it is part of natural variability,” adds Dr Gößling.

“At the moment it’s very difficult to say.”

Despite this uncertainty, scientists emphasize that humans still have control over the future climate and that strong emissions reductions can mitigate the consequences of warming.

“Even if 1.5 degrees is exceeded, we can probably limit warming to 1.6°C, 1.7°C or 1.8°C this century,” says Dr Hausfather.

“It will be much better than if we continue to burn coal, oil and gas relentlessly and end up at 3°C ​​or 4°C – that still really matters.”