OCEAN WARMTH
Last month, Copernicus said that global temperatures averaged across 2023 and 2024 exceeded 1.5 degrees Celsius for the first time.
This did not represent a permanent breach of the long-term 1.5 degrees Celsius warming target under the Paris climate accord – but a clear sign that the limit was being tested.
Scientists warn that every fraction of a degree of warming above 1.5 degrees Celsius increases the intensity and frequency of extreme weather events like heatwaves, heavy rainfall and droughts.
Copernicus said Arctic sea ice in January hit a monthly record low, virtually tied with 2018. Analysis from the United States this week put it at the second-lowest in that dataset.
Overall, 2025, is not expected to follow 2023 and 2024 into the history books: scientists predict it will rank the third hottest year yet.
Copernicus said it would be closely monitoring ocean temperatures throughout 2025 for hints about how the climate might behave.
Oceans are a vital climate regulator and carbon sink, and cooler waters can absorb greater amounts of heat from the atmosphere, helping to lower air temperatures.
They also store 90 per cent 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 this what has been happening over the past couple of years?”
Sea surface temperatures have been exceptionally warm over 2023 and 2024, and Copernicus said readings in January were the second highest on record.
“That is the thing that is a little puzzling – why they remain so warm,” Nicolas said.
