The internationally agreed goal to keep the world’s temperature rise below 1.5C is now “deader than a doornail”, with 2024 almost certain to be the first individual year above this threshold, climate scientists have gloomily concluded – even as world leaders gather for climate talks on how to remain within this boundary.
Three of the five leading research groups monitoring global temperatures consider 2024 on track to be at least 1.5C (2.7F) hotter than pre-industrial times, underlining it as the warmest year on record, beating a mark set just last year. The past 10 consecutive years have already been the hottest 10 years ever recorded.
Although a single year above 1.5C does not itself spell climate doom or break the 2015 Paris agreement, in which countries agreed to strive to keep the long-term temperature rise below this point, scientists have warned this aspiration has in effect been snuffed out despite the exhortations of leaders currently gathered at a United Nations climate summit in Azerbaijan.
“The goal to avoid exceeding 1.5C is deader than a doornail. It’s almost impossible to avoid at this point because we’ve just waited too long to act,” said Zeke Hausfather, climate research lead at Stripe and a research scientist at Berkeley Earth. “We are speeding past the 1.5C line an accelerating way and that will continue until global emissions stop climbing.”
Last year was so surprisingly hot, even in the context of the climate crisis, that it caused “some soul-searching” among climate scientists, Hausfather said. In recent months there has also been persistent heat despite the fading of El Niño, a periodic climate event that exacerbated temperatures already elevated by the burning of fossil fuels.
“It’s going to be the hottest year by an unexpectedly large margin. If it continues to be this warm it’s a worrying sign,” he said. “Going past 1.5C this year is very symbolic, and it’s a sign that we are getting ever closer to going past that target.”
Climate scientists broadly expect it will become apparent the 1.5C target, agreed upon by governments after pleas from vulnerable island states that they risk being wiped out if temperatures rise further than this, has been exceeded within the coming decade.
Despite countries agreeing to shift away from fossil fuels, this year is set to hit a new record for planet-heating emissions, and even if current national pledges are met the world is on track for 2.7C (4.8F) warming, risking disastrous heatwaves, floods, famines and unrest. “We are clearly failing to bend the curve,” said Sofia Gonzales-Zuñiga, an analyst at Climate Analytics, which helped produce the Climate Action Tracker (Cat) temperature estimate.
However, the Cop29 talks in Baku have maintained calls for action to stay under 1.5C. “Only you can beat the clock on 1.5C,” António Guterres, secretary general of the UN, urged world leaders on Tuesday, while also acknowledging the planet was undergoing a “masterclass in climate destruction”.
Yet the 1.5C target now appears to be simply a rhetorical, rather than scientifically achievable, one, bar massive amounts of future carbon removal from as-yet unproven technologies. “I never thought 1.5C was a conceivable goal. I thought it was a pointless thing,” said Gavin Schmidt, a climate scientist at Nasa. “I’m totally unsurprised, like almost all climate scientists, that we are shooting past it at a rapid clip.
“But it was extremely galvanizing, so I was wrong about that. Maybe it is useful; maybe people do need impossible targets. You shouldn’t ask scientists how to galvanize the world because clearly we don’t have a fucking clue. People haven’t got a magic set of words to keep us to 1.5C, but we have got to keep trying.
“What matters is we have to reduce emissions. Once we stop warming the planet, the better it will be for the people and ecosystems that live here.”
The world’s decision-makers who are collectively failing to stem dangerous global heating will soon be joined by Donald Trump, who is expected to tear down climate policies and thereby, the Cat report estimates, add at least a further 0.04C to the world temperature.
Despite this bleak outlook, some do point out that the picture still looks far rosier than it did before the Paris deal, when a catastrophic temperature rise of 4C or more was foreseeable. Cheap and abundant clean energy is growing at a rapid pace, with peak oil demand expected by the end of this decade.
“Meetings like these are often perceived as talking shops,” said Alexander De Croo, the Belgian prime minister, at the Cop29 summit. “And yes, these strenuous negotiations are far from perfect. But if you compare climate policy now to a decade ago, we are in a different world.”
Still, as the world barrels past 1.5C there lie alarming uncertainties in the form of runaway climate “tipping points”, which once set off cannot be halted on human timescales, such as the Amazon turning into a savanna, the collapse of the great polar ice sheets, and huge pulses of carbon released from melting permafrost.
“1.5C is not a cliff edge, but the further we warm up the closer we get to unwittingly setting off tipping points that will bring dramatic climate consequences,” said Grahame Madge, a climate spokesman at the UK Met Office, who added that it would now be “unexpected” for 2024 to not be above 1.5C.
“We are edging ever closer to tipping points in the climate system that we won’t be able to come back from; it’s uncertain when they will arrive, they are almost like monsters in the darkness,” Madge said.
“We don’t want to encounter them so every fraction of a degree is worth fighting for. If we can’t achieve 1.5C, it will be better to get 1.6C than 1.7C, which will be better than getting 2C or more.”
Hausfather added: “We aren’t in for a good outcome either way. It’s challenging. But every tenth of a degree matters. All we know is that the more we push the climate system away from where it has been for the last few million years, there be dragons.”