Climate report shows 1.5C limit on global warming will be breached by 2030
More than 70 scientists, including contributors to the United Nations Intergovernmental Panel on Climate Change (IPCC), have raised the alarm over record human-induced global warming and surging marine heatwaves, in an annual study published between IPCC assessments.
“These indicators represent an essential monitoring of the vitals of a patient exhibiting ever increasingly troubling symptoms,” said Peter Thorne, one of the study's authors and deputy chair of the UN-backed Global Climate Observing System (GCOS).
"They all rest upon a suite of global observation capabilities which are, for the first time in my lifetime, systematically either actively degrading or at risk."
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Rapid heating
The study published in the journal Earth System Science Data found that global temperatures reached about 1.39C above pre-industrial levels in 2025, with nearly all of that warming – 1.37C – driven by human activities.
Countries around the world agreed under the 2015 Paris climate accord to limit warming to well below 2C, and preferably 1.5C, to avoid the worst consequences of climate change.
But the report found the world is accumulating heat at a rapid pace, worsening “Earth's energy imbalance” – the rate at which energy enters and leaves the planet.
“Without human influence, it should be close to zero, but it has been growing since the 1970s and is now at a record high, doubling in recent decades,” Piers Forster, the study's lead author and a physical climate change professor at England's University of Leeds, said.
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Record emissions
The high rate of warming is due to a combination of greenhouse gas emissions reaching an all-time high and a reduction in aerosol pollution, which has weakened a cooling effect because the particles reflect sunlight.
CO2 emissions remain the main driver of global warming and are at a record high.
While scientists said emissions are slowing, the “carbon budget” – the amount of CO2 that can still be emitted to keep warming under 1.5C – could be exhausted in around three years.
“Given that greenhouse gas emissions are still on the rise, keeping global warming below this [1.5C] threshold now seems unachievable,” said Aurélien Ribes, a climate scientist at the French meteorological service Meteo France.
The sea rose by around 23cm between 1901 and 2025 and is now rising at a faster pace of 3.84mm per year, due to melting land-based ice and thermal expansion as the ocean warms.
Marine heatwave days, a new indicator added to this year's report, have more than tripled since1991, reaching 65 on average in 2025.
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Monitoring under threat
Launched in 2023, the Indicators of Global Climate Change provides an annual update for policymakers between major IPCC assessments, with the next due in 2028 or 2029.
The report relies on around 40 global datasets from satellites and land, sea and air instruments, including weather stations, ships, buoys and weather balloons.
However, the scientists warned that “future monitoring of these indicators, such as ocean and satellite measurements of the Earth's energy imbalance, [is] threatened by geopolitical and public funding decisions”.
Funding for the UN's World Meteorological Organization has diminished, while the Global Climate Observing System “is also under threat”, the report said.
Several satellite programmes are at risk, including in the United States, where the Trump administration recently decided to remove hundreds of deep-sea instruments.
Scientists also cited falling on-site measurements in Africa, the west Pacific and South America, as well as the recent de-funding of the plane that carries the United Kingdom's atmospheric observation system.
(with newswires)