Two new studies suggest Paris climate goal is dead. One scientist is going even further

CNN

10-02-2025

Swaths of the US may be grappling with frigid weather, but for the planet as a whole, heat records are being obliterated — and it spells very bad news. Two new studies conclude it's a signal the planet is likely on track to breach the Paris climate agreement goal of restricting global warming to 1.5 degrees Celsius.
The studies, both published Monday in the journal Nature Climate Change, are the latest evidence the world is failing to tackle the climate crisis, and they come just weeks after an even starker warning from renowned climate scientist James Hansen, who said the planet was on course to shoot past 2 degrees of global warming over the next two decades.
While many scientists have said these levels of warming can be avoided with immediate, rapid emission cuts, the chances of this seem increasingly slim as international climate action falters. One of President Donald Trump's first actions was to pull the US out of the Paris climate agreement and now others, including Argentina and Indonesia, are reportedly mulling withdrawal.
The Paris agreement is hugely symbolic. In 2015, almost every country in the world agreed to keep global warming to well below 2 degrees above the period before humans began burning large amounts of fossil fuels, with the ambition of limiting warming to 1.5 degrees.
Above 1.5 degrees, scientists say increasingly extreme heat, drought, floods and fires will become hard for humans and ecosystems to adapt to. At 2 degrees, millions of more lives would be at risk and the danger rises significantly of triggering tipping points such as ice sheet melting and the death of the world's coral reefs.
Since 2015, 1.5 has become synonymous with staving off more catastrophic climate change. Yet global temperatures have kept rising. Last year was the first calendar year to breach 1.5 degrees.
As Paris goals refer to averages over around two decades, rather than single months or years, this means breaching the agreement can only be confidently confirmed in hindsight, once it's too late.
So scientists behind these two new papers attempted to determine whether the world is already in its first long-term period of 1.5 degree warming. The news is not good.
The study by Alex Cannon, a research scientist at Environment and Climate Change Canada, found there was a 60% to 80% chance the Paris threshold has already been crossed given 12 consecutive months have already been at least 1.5 degrees.
If the world experiences 18 consecutive months at or above the 1.5 degree limit, it will be 'virtually certain' the Paris agreement has been breached, the report found.
The other paper, led by Emanuele Bevacqua, a climate scientist at the Helmholtz Centre in Germany, used real-world climate data and climate modeling. Looking at historical warming trends, it found the first single year to breach a temperature threshold also fell within the first 20-year period in which average temperatures reached the same threshold.
If these trends continue, it is almost certain 2024 will fall within the first 20-year period of 1.5-degree warming, the report concluded.
Both papers stress that rapid and strong climate action can still reduce the likelihood of breaching the Paris agreement goals over the next years and decades.
'To all intents and purposes, breaching the 1.5 degree threshold is a given,' said Richard Allen, a climate science professor at the University of Reading, who was not involved in the studies. 'We need to double down efforts to avoid the even more dangerous 2-degree Celsius threshold by rapidly and massively cutting greenhouse gas emissions.'
For others, however, that ship has already sailed. The climate scientist James Hansen, who was among the first to publicly warn the world about climate change, said last year the 1.5 goal was 'deader than a doornail.'
This month he co-authored a paper which concluded global warming is accelerating faster than expected, due in large part to regulations to reduce shipping pollution. While this pollution is a human health hazard, it also has the effect of reflecting sunlight away from the Earth.
As a result, he said, global heating is likely to exceed 2 degrees in the next few decades with devastating consequences, including ice sheet melt and sea level rise.
The new papers are undoubtedly bad news, said Daniela Schmidt, professor of Earth sciences at the University of Bristol, but she warned against fixating on 1.5 degrees. It 'has the real risk of reducing actions, demotivating all of us,' if it's surpassed, she said.
A lack of ambition will keep the world on its current warming trajectory of around 3 degrees, she added. 'Such warming has immense, and in parts irreversible, consequences for nature and people.'