As Southern California swelters under its harshest heat wave of the year, International climate officials have confirmed that the summer of 2024 was the hottest on record on Earth.
The average global temperature in June, July and August — known as boreal summer in the Northern Hemisphere — was a record-breaking 62.24 degrees Celsius (141.84 degrees Fahrenheit), according to the European Union’s Copernicus Climate Change Service. The season was marked by explosive wildfires, scorching heat waves and heat-related deaths in California and many other parts of the world.
“Over the last three months of 2024, the planet has experienced the hottest June and August, the hottest day on record and the hottest northern summer on record,” reads a statement from Samantha Burgess, Copernicus Deputy Director. “The temperature-related extremes we have witnessed this summer will only intensify and have more devastating consequences for people and planet unless we take urgent action to reduce greenhouse gas emissions.”
Not only was it a hot summer, but August effectively tied 2023 as the hottest August on record on the planet, with the global average temperature at about 62.28 degrees, the agency said.
In fact, the entire year so far has been so warm that, even with four months to go, 2024 is almost certain to surpass 2023 as the warmest year on record on Earth.
This is because the global mean temperature anomaly from January to August was the highest on record for the period, and 0.41 degrees warmer than the same period last year.
The average anomaly would have to fall by more than half a degree for 2024 to be no warmer than 2023, which has never happened in the entire Copernicus data set, the agency said.
A woman sunbathes in a park in Milan, Italy, during a July heatwave.
(Luca Bruno / Associated Press)
The almost unrelenting series of months of record-breaking temperatures has scientists and climate officials concerned as the planet hurtles toward a dangerous tipping point.
“We are playing Russian roulette with our planet and we need an exit ramp from the highway to climate hell,” said António Guterres, secretary-general of the United Nations, during a speech delivered at the start of a record summer in June.
While rising Earth temperatures are somewhat consistent with the high end of climate model projections, the heat has also defied some expectations, according to Zeke Hausfather, a climate scientist at Berkeley Earth.
“The heat in 2024 has persisted longer than many of us expected, and the past few months have been similar to the extremes we saw in the second half of 2023,” Hausfather said in an email.
This is particularly puzzling because El Niño — a weather pattern associated with warmer global temperatures — dissipated toward the end of May but did not lead to an anticipated decline in global temperatures. There is typically a three-month lag between peak El Niño conditions and the global surface temperature response, “but even with that we should have already started to cool down a bit,” Hausfather said.
The fact that conditions have remained consistently warm without El Niño may be an indication that other factors are at play, he said. Some theories include a change in aerosol-delivery regulations that allowed more sunlight to reach Earth; an uptick in the 11-year solar cycle; and the 2022 eruption of the Hunga Tonga-Hunga Ha'apai volcano, which may have trapped some heat in the atmosphere.
But even those factors “don’t seem to completely match what we’re seeing,” Hausfather said.
Also worrying is the steady rise in temperatures beyond the international limit of 2.7 degrees, or 1.5 degrees Celsius, set by nearly 200 nations in the 2015 Paris climate agreement in an effort to prevent the worst effects of global warming.
The boundary is measured relative to the pre-industrial era, or the period before humans began significantly altering the planet's climate through greenhouse gas and other fossil fuel emissions, and typically uses temperature data from between 1850 and 1900.
August 2024 was the 13th month in a 14-month period to exceed that benchmark, as the global average temperature stood about 2.72 degrees (or 1.51 degrees Celsius) above pre-industrial levels, according to Copernicus. The streak was only broken in July, which fell just below the limit for the first time in a year.
Experts say a single year of warming above the limit does not mean humanity has officially exceeded the limit, but it is a worrying trend that is moving in the wrong direction.
“It’s certainly a worrying sign that global temperatures have been persistently above 1.5 degrees Celsius for so long,” Hausfather said. He calculated that the probability of 2024 overtaking 2023 as the warmest year on record is above 95%, and said it is also very likely to be the first year above 1.5 degrees Celsius in the Copernicus dataset, although other datasets may disagree due to slight differences in measurements.
Tourists walk with umbrellas in front of the Parthenon on the ancient Acropolis in central Athens, in June.
(Petros Giannakouris/Associated Press)
And while summer was marked by sweltering heat on land, the planet’s oceans were also on the boil. Ocean waters reaching record temperatures contributed to a violent start to the Atlantic hurricane season this year, with Hurricane Beryl becoming the earliest Category 5 hurricane on record in the basin when it formed in late June.
In August, Arctic sea ice extent also fell 17% below average, the fourth-lowest level for the month in the satellite record and “clearly further below average than the same month in the previous three years,” Copernicus officials said.
Antarctic sea ice extent was 7% below average, the second-lowest extent for August on record in satellite data.
The report comes as Southern California endures several consecutive days of triple-digit temperatures, including highs of more than 110 degrees in parts of Los Angeles County.
In fact, the summer was remarkably warm across much of the Golden State, with July being considered the warmest month in California. The hottest month on record.
Officials at Death Valley National Park, where two people died from heat-related illnesses, confirmed the park experienced its hottest summer on record, with nine consecutive days of 125 degrees or higher. The park's 24-hour average temperature in June, July and August was 104.5 degrees, surpassing the previous record of 104.2 degrees set in 2021 and 2018.
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Daniel Swain, a climate scientist at UCLA, said the current heat wave will likely break some daily records in Southern California, which has fared much better than the rest of the state during this year's hot summer.
“It is almost certain that [bring] “The hottest day of the year for much of Southern California, and perhaps even the hottest day in several years for parts of Southern California,” Swain said during a news conference. Briefing on Wednesday“This is a significant heat event.”
Large swaths of the region are also likely to experience some of the warmest nights on record for this time of year, he said.
“It may not sound as dramatic as, say, the hottest days on record or the highest afternoon maximum temperatures, but those nighttime temperatures are pretty significant from a human health impact perspective, ecosystem health perspective, and also a wildfire perspective,” he said.
In fact, heat is the deadliest of all weather hazards, and a recent study confirmed that heat-related deaths are on the rise in the United States.
The latest seasonal outlook from the National Oceanic and Atmospheric Administration indicates that above-normal temperatures could persist across much of the country through at least November.
Residents of Phoenix, Arizona, have now endured more than 100 consecutive days of temperatures above 100 degrees, breaking the previous record of 76 days set in 1993, according to the National Weather Service.
