Greenhouse gas missions have driven 1.44°C of warming since pre-industrial times
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The world could see its first year of warming above 2°C by the end of the decade, leading climate scientists have warned for the first time.
Each year, researchers at the Met Office – the UK’s national weather service – use observational climate data and modelling from institutions around the world to predict the global climate for the coming five years.
Their results suggest the average temperature in a single year could exceed 2°C above pre-industrial times by 2029, a result that would mark a significant and sobering milestone in the fight against climate change.
“That was effectively impossible a few years ago,” Adam Scaife at the Met Office told reporters during a briefing. Such an event would be “completely unprecedented”, he added.
The Paris Agreement of 2015 aims to limit global warming to well below 2°C above pre-industrial levels, with an additional target of keeping warming at or below 1.5°C. Those aims would only be missed if that level of temperature rise is sustained over a couple of decades.
Last year was the first single year to record temperatures above the 1.5°C threshold, driven by rising emissions and a strong El Niño weather pattern. There is an 86 per cent chance that at least one of the next five years will breach the same threshold, according to the Global Annual to Decadal Climate Update, produced for the UN’s World Meteorological Organization (WMO).
Meanwhile, there is a 70 per cent chance that average warming for the entire 2025-2029 period will exceed 1.5°C, the team says. That compares with a 47 per cent chance given in the 2024 report, which covered the period 2024-2028. “These latest predictions suggest that we really are very close now to having 1.5°C years [being] commonplace,” said Scaife. “These are shocking statistics.”
The chances of seeing a year above 2°C of warming are still very slim, with the WMO/Met Office team estimating the probability at 1 per cent. “It’s exceptionally unlikely, but it could happen,” Leon Hermanson at the Met Office said during the briefing. “It’s not something anyone wants to see, but that is what the science is telling us.”
Pushing the annual average temperature above 2°C is likely to require a “perfect storm” of factors, said Scaife. These could include a powerful El Niño pattern that would drive warmth from the Pacific Ocean, alongside a positive Arctic Oscillation, which would increase land warming across Eurasia.
But while the odds are currently slim, the likelihood of a 2°C year is expected to increase dramatically over the coming years unless greenhouse gas emissions fall rapidly.
It has been only a decade since the Met Office and WMO first confirmed the possibility that the world could see a year above 1.5°C of warming. Now the world is hovering perilously close to exceeding the 1.5°C threshold: the report estimates that the long-term average temperature is 1.44°C above pre-industrial levels.
“Where we were in 2015 with 1.5°C is where we are now with 2°C,” said Hermanson. “If things continue the way they are, the chance of that will also increase very steeply.”
Chris Hewitt at the WMO said there is still a window of opportunity to avoid the most dangerous effects of climate change, by radically cutting emissions to hold temperatures as close to the 1.5°C threshold as possible. “Every fraction of a degree matters,” he said.
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