Pedestrians take a break as they cross the Brooklyn Bridge during a heat wave in New York on June 21, 2024. — Graham Dickie/The New York Times
WITH the addition of 2024, yet another record-hot year, the past 10 years have been the 10 hottest in nearly 200 years of record- keeping, the World Meteorological Organisation (WMO) reports.
“That’s never happened before,” said Chris Hewitt, climate services division director. It marks the first time since record keeping began that all of the 10 hottest years have fallen within the most recent decade.
Last year was the single warmest year on record, surpassing even 2023’s wide lead over other recent years. The planet’s surface was about 1.55°C warmer than its average during a reference period that approximates the preindustrial era, from 1850-1900.
The WMO report includes input from dozens of experts and institutions from around the world and sheds further light on the record-breaking heat of 2024 and places it in the context of Earth’s long-term warming from climate change.
The extra energy in the atmosphere and oceans helped fuel climate-related disasters worldwide. Extreme weather events like drought, storms, and wildfires displaced hundreds of thousands of people, the report says.
Atmospheric levels of greenhouse gases released from fossil fuel combustion continue to rise. In 2024, the concentration of carbon dioxide hit amounts unseen in at least two million years. Con-centrations of two other important greenhouse gases, methane and nitrous oxide, reached levels unseen in at least 800,000 years.
When countries signed the Paris Agreement in 2015, they agreed to try to limit global warming to 1.5°C above pre- industrial levels.
“While a single year above 1.5°C of warming does not indicate that the long-term temperature goals of the Paris Agreement are out of reach, it is a wake-up call that we are increasing the risks to our lives, economies, and to the planet,” Celeste Saulo, secretary-general of the WMO, said in a statement.
The new report estimates that long-term warming has reached 1.25°C to 1.41°C above pre-industrial levels, although the margins of error for some estimates extend beyond 1.5°C. The report authors estimate that last year, El Nino and other factors contributed an additional 0.1 or 0.2 of a degree of temporary warming.
El Nino is a natural climate pattern that tends to slightly raise the overall surface temperature of the planet. Record warmth, however, continued into 2025, even through El Nino’s transition into the opposing pattern, La Nina.
“It’s been really quite extraordinary to see that warmth continue for so long,” John Kennedy, the scientific coordinator and lead author of the report, said during a call with reporters.
This warmth is especially apparent in the oceans, where key indicators of climate change are accelerating.
The oceans have so far absorbed around 90% of the additional heat trapped inside Earth’s atmosphere by greenhouse gases. The oceans’ heat content – a way to measure this warmth throughout different depths – also reached a record high last year. Over the past two decades, from 2005 to 2024, the oceans warmed more than twice as fast as they did from 1960 to 2005, according to the report.
Increased ocean temperatures have had devastating consequences for marine life. By April 2024, warm-water corals had been bleached in every ocean basin where they grow.
Global average sea-level rise also reached a record high in 2024, according to the report. The speed at which the seas are rising has also more than doubled in recent years: 4.7mm per year in the past decade, from 2015 to 2024, compared with 2.1mm per year from 1993 to 2002.
The WMO’s work depends on international cooperation among its 101 member countries, including the United States.
“If you look at how weather has progressed since the initiation of the WMO in 1950, you can now see that you can have the forecast on your smartphone,” said Omar Baddour, the WMO’s chief of climate monitoring.
“You cannot believe how much collaboration is behind this.”
Data from US space agency Nasa and the US National Oceanic and Atmospheric Administration, which recently lost hundreds of staff positions as part of the rapid, large-scale cuts to the federal bureaucracy Donald Trump’s administration undertook beginning this year, are included in the WMO’s new report. – ©2025 The New York Times Company
This article originally appeared in The New York Times.
