By AFP - Agence France Presse
January heat record “surprising”: EU monitor
Last month was the warmest January on record, Europe's climate monitor said Thursday, despite expectations that cooler La Nina conditions could end a string of global temperature records.
The Copernicus Climate Change Service said January was 1.75°C warmer than the pre-industrial era, extending a persistent run of record highs throughout 2023 and 2024 as man-made greenhouse gas emissions turn up the global thermostat.
Climate scientists had expected this exceptional period to subside after an El Nino warming event peaked in January 2024, and conditions gradually shifted to an opposite, cooling La Nina phase.
But the heat has remained at record or near-record levels ever since, sparking a debate among scientists about what other factors could be pushing warming to the upper limit of expectations.
“That's what makes it a bit surprising... you're not seeing that cooling effect, or at least temporary brake, on global temperatures that we expected to see,” Julien Nicolas, a climate scientist at Copernicus, told AFP.
La Nina is expected to be weak, and Copernicus said that the prevailing temperatures in parts of the equatorial Pacific Ocean suggest “a slowing or halting of the movement towards” the cooling phenomenon.
Nicolas said the phenomenon could disappear completely by March.
- Ocean heat
Last month, Copernicus said that average global temperatures in 2023 and 2024 exceeded 1.5 degrees Celsius for the first time.
This did not represent a permanent breach of the 1.5°C long-term warming target set out in the Paris climate agreement but a clear sign that the limit was being tested.
Scientists warn that every fraction of a degree of warming above 1.5C increases the intensity and frequency of extreme weather events, such as heat waves, heavy rains, and droughts.
Copernicus said that Arctic sea ice in January hit a monthly record low, virtually tied with 2018. An analysis by the US this week put it at the second lowest level in that data set.
Overall, 2025 is not expected to follow 2023 and 2024 in the history books: scientists predict it will be the third warmest year so far.
Copernicus said it will be closely monitoring ocean temperatures throughout 2025 to get clues as to how the climate might behave.
The oceans are a vital climate regulator and carbon sink, and cooler waters can absorb greater amounts of heat from the atmosphere, helping to reduce air temperatures.
They also store 90% of the excess heat trapped by humanity's release of greenhouse gases.
“This heat is bound to resurface periodically,” said Nicolas.
“I think that's also one of the questions: is that what's been happening in recent years?”
Sea surface temperatures were exceptionally warm in 2023 and 2024, and Copernicus said January's readings were the second highest ever recorded.
“That's what's a bit puzzling - why they keep getting so warm,” said Nicolas.
- The debate
Scientists are unanimous that the burning of fossil fuels has been largely responsible for long-term global warming and that natural climate variability can also influence temperatures from one year to the next.
But natural warming cycles, such as El Niño, were unable to explain what was happening in the atmosphere and seas on their own, and the answers were being sought elsewhere.
One theory is that a global switch to cleaner shipping fuels in 2020 accelerated warming by reducing sulphur emissions that make clouds more mirror-like and reflective of sunlight.
In December, another peer-reviewed article looked at whether the reduction in low clouds had allowed more heat to reach the Earth's surface.
“It's still really a matter of debate,” said Nicolas.
The EU monitor uses billions of measurements from satellites, ships, aircraft, and weather stations to aid its climate calculations.
Its records date back to 1940, but other sources of climate data - such as ice cores, tree rings, and coral skeletons - allow scientists to extend their conclusions using evidence from a much more distant past.
Scientists say that the period being experienced now is probably the hottest the Earth has experienced in the last 125,000 years.
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