Strangely warm winter has climate fingerprints all over, study says
Winter was strangely warm for half the world’s population, caused in many places by the burning of fossil fuels, according to an analysis of temperature data from hundreds of locations around the world.
That ties in with the findings published late Wednesday by the European Union’s climate monitoring organization Copernicus: The world as a whole experienced the warmest February on record, marking the ninth month in a row with record temperatures. Even more startling, global ocean temperatures in February were at a record high for any time of year, Copernicus said.
Taken together, the two sets of figures offer a portrait of an undeniably warming world that, combined with a natural El Niño weather pattern this year, has made winter unrecognizable in some places.
The first analysis, carried out by Climate Central, an independent research group based in New Jersey found that in several cities in North America, Europe and Asia, winters were not only unusually warm, but that climate change played a clearly identifiable role.
Climate Central looked at anomalies in December and January temperature data in 678 cities around the world and asked: How important are the fingerprints of climate change for these unusual temperatures? That is, the researchers tried to isolate the usual variability of weather from the influence of climate change.
“There’s the temperature,” says 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 stood out for experiencing an unusually warm winter and for the impact of climate change, which is mainly caused by the burning of coal, oil and other fossil fuels that release greenhouse gases into the atmosphere. “Really off the charts,” said Dr. Pershing. “There is no ice on most of the great lakes. That is remarkable.”
For example, Minneapolis was almost 5.6 degrees Celsius warmer than average between December and February. The fingerprints of climate change could be detected for 33 days, which amounts to a third of the winter season.
Tehran was an average of 4.2 degrees Celsius warmer in the same three-month period. The effects of human-induced climate change could be observed over 68 winter days.
The average winter temperature in Milan was about 2 degrees Celsius higher, but there was a strong signal of climate change for 55 days.
Elsewhere, average winter temperatures did not vary greatly, although there were some significantly warm days, 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 impact of carbon pollution.”
In some parts of the world, unusually warm winter weather was overshadowed by other crises, such as war. Several cities in Ukraine were significantly warmer than normal, showing the fingerprints of climate change there too. Kiev, for example, was almost 3 degrees Celsius warmer on average this winter, and climate change played a role for 33 days. The same goes for several cities in Iran, Iraq and Afghanistan.
In the tropical belt, where temperatures tend to be much hotter on average, climate signals are easier to detect, although temperature increases may be smaller. For example, Jakarta and Kuala Lumpur were barely 1 degree Celsius warmer on average. But the effects of climate change could be observed for almost the entire three-month period.
It’s not just individual cities that are setting records this winter. According to the Copernicus Climate Change Service, February 2024 was the warmest February on record worldwide. It was 1.77 degrees Celsius above the average February temperature in the recent pre-industrial era of 1850-1900.
This is the ninth month in a row in which the temperature record for that month has been broken. All told, the past twelve months were the warmest twelve consecutive months on record: 1.56 degrees Celsius above the 1850-1900 average.
“A year ago, the fact that global temperatures would rise 1.5 degrees Celsius above pre-industrial levels during a given month would have been considered exceptional,” Julien Nicolas, a senior scientist at Copernicus, said via email. Now it has happened repeatedly.
This does not mean that we have exceeded the Paris Agreement’s international target of halting global warming at 1.5 degrees Celsius above pre-industrial temperatures. For that to happen, the planet would have to be 1.5 degrees warmer for several years, long enough to reflect a more permanent change.
For now, the ocean has been exceptionally hot in the short term. Earth’s average sea surface temperature in February was the warmest on record, surpassing the previous record set in August 2023.