Winter Heat Waves and Hottest Ocean Ever

Winter was weirdly warm for half the world’s population, driven in many places by the burning of fossil fuels, according to an analysis of temperature data from hundreds of locations worldwide.

That aligns with the findings published late Wednesday by the European Union’s climate monitoring organization, Copernicus: The world as a whole experienced the hottest February on record, making it the ninth consecutive month of record temperatures. Even more startling, global ocean temperatures in February were at an all-time high for any time of year, according to Copernicus.

Taken together, the two sets of figures offer a portrait of an unequivocally warming world that, combined with a natural El Niño weather pattern this year, has made winter unrecognizable in some places.

The first analysis, conducted by Climate Central, an independent research group based in New Jersey, found that in several cities in North America, Europe and Asia, not only was winter unusually warm, but climate change played a distinctly recognizable role.

Climate Central looked at anomalies in December and January temperature data in 678 cities worldwide and asked: How important are the fingerprints of climate change for these unusual temperatures? That is to say, its researchers tried to isolate the usual variability of the weather from the influence of climate change.

“There’s the temperature,” said Andrew Pershing, Climate Central’s vice-president for science, “and then there’s our ability to really detect that climate signal in the data.”

Cities in the Midwestern United States jumped out for experiencing an extraordinarily warm winter and for the influence of climate change, which is caused mainly by the burning of coal, oil and other fossil fuels that release greenhouse gases into the atmosphere. “Really off the charts,” Dr. Pershing said. “No ice on most of the great lakes. That’s remarkable.”

Minneapolis, for instance, was nearly 5.6 degrees Celsius warmer than average between December and February. The fingerprints of climate change could be detected for 33 days, essentially a third of the winter season.

Tehran was 4.2 degrees Celsius warmer on average during the same three-month period. The effects of human-made climate change could be detected over 68 days of winter.

Milan’s winter average temperature was roughly 2 degrees Celsius higher, but there was a strong climate change signal over 55 days,.

Elsewhere, even though there were a few significantly hot days, winter average temperatures didn’t vary wildly and the climate signal was less pronounced.

The Climate Central report, also published Wednesday, concluded that 4.8 billion people worldwide “experienced at least one day of temperatures that would be virtually impossible without the influence of carbon pollution.”

In some parts of the world, the unusually warm winter weather was overshadowed by other crises, such as war. Several cities in Ukraine were significantly warmer than usual, and there, too, were the fingerprints of climate change. Kyiv, for instance, was nearly 3 degrees Celsius warmer on average this winter, and climate change was seen to have played a role for 33 days. Likewise, in several cities of Iran, Iraq and Afghanistan.

In the tropical belt, where it’s usually much hotter on average, climate signals are easier to detect, though temperature increases can be smaller. Jakarta and Kuala Lumpur for instance were barely 1 degree Celsius warmer on average. But the effects of climate change could be detected for nearly the entire three-month period.

It’s not just individual cities that set records this winter. Globally, February 2024 was the warmest February on record, according to the Copernicus Climate Change Service. It was 1.77 degrees Celsius above the average February temperature in the recent preindustrial era from 1850-1900.

This is the ninth month in a row to break the temperature record for that respective month. Taken together, the past 12 months have been the hottest 12 consecutive months on record: 1.56 degrees Celsius above the average from 1850-1900.

“A year ago, the fact that the global temperature for a particular month would reach 1.5 degrees C above the pre-industrial level would have been considered exceptional,” said Julien Nicolas, a senior scientist at Copernicus, via email. Now, it’s happened repeatedly.

This doesn’t mean we have exceeded the international Paris Agreement goal of stopping global warming at 1.5 degrees Celsius above the preindustrial temperature. For that to happen, the planet would need to be 1.5 degrees warmer for several years, long enough to reflect a more permanent change.

For now, in the short term, the ocean has been particularly hot. The average global sea-surface temperature in February was the warmest recorded for any month, surpassing the previous record set in August 2023.