'Climate Breakdown Has Begun': Summer of 2023 Was Hottest Ever Recorded

Climate scientists across the world have been alarmed over the past three months by fast-spreading wildfires, prolonged and deadly heatwaves, and numerous shattered heat records across the northern hemisphere both in the oceans and on land—and data released Tuesday confirmed that the past three months have been the hottest summer on record, driven by humans' continued emission of heat-trapping gases and compounded by El Niño.

The Copernicus Climate Change Service (C3S), the European Union's climate agency, found that the global average temperature during June, July, and August reached 16.77°C (62.18°F), which was 0.66°C or 1.18°F above the 1991-2020 average.

The previous temperature record was set in 2019 and was 0.29°C (0.5°F) lower than this year's high.

Last month was the hottest August on record "by a large margin," said the World Meteorological Organization, with the average temperature 1.5°C higher than the preindustrial average.

United Nations Secretary-General António Guterres said Wednesday the world is experiencing the consequences of "our fossil fuel addiction," which "scientists have long warned" would be unleashed if humans continue extracting oil and gas instead of rapidly shifting to renewable energy sources.

"Our planet has just endured a season of simmering—the hottest summer on record. Climate breakdown has begun," said Guterres.

"In the southern hemisphere Antarctic sea ice extent was literally off the charts, and the global sea surface temperature was once again at a new record. It is worth noting that this is happening BEFORE we see the full warming impact of the El Niño event."

C3S released the data as the Eastern United States experienced a "dangerous heatwave," with cities including New York and Washington, D.C. announcing heat advisories.

As the World Weather Attribution (WWA) said earlier this summer, the extreme heat felt across North America and Europe in July—the hottest month ever on record, followed by August—would have been "virtually impossible" without planetary heating and the climate crisis.

Scientists at the WWA also found that the hot, dry conditions that allowed wildfires to spread rapidly in Eastern Canada were made twice as likely by the climate emergency, and independent scientists at Climate Central determined that the current heat forecast in the United Kingdom—with temperatures over 33°C or 91°F expected in London on Saturday—was made five times more likely.

Friederike Otto, a senior lecturer on climate change and the environment at Imperial College London, toldThe Guardian that "breaking heat records has become the norm in 2023."

"Global warming continues because we have not stopped burning fossil fuels," said Otto. "It is that simple."

Scientists last observed a powerful El Niño warming event, which is marked by very high temperatures in the Pacific Ocean near the equator, in 2016, which currently holds the record for the hottest January-August period, followed by this year.

El Niño is still developing this year, and experts have warned that next summer could see even more intense heatwaves and wildfires as the effects of the warming phenomenon are typically observed the year after it develops.

"The northern hemisphere just had a summer of extremes—with repeated heatwaves fueling devastating wildfires, harming health, disrupting daily lives, and wreaking a lasting toll on the environment," said Petteri Taalas, secretary-general of the WMO. "In the southern hemisphere Antarctic sea ice extent was literally off the charts, and the global sea surface temperature was once again at a new record. It is worth noting that this is happening BEFORE we see the full warming impact of the El Niño event."

Mark Maslin, professor of earth system science at University College London, told The Guardian that the news from C3S "is a wake-up call to international leaders that we must rapidly reduce carbon emissions now."

"Let us hope this message hits home at COP28... this December and action actually happens," Maslin said.

Advocates have raised alarm about the appointment of Sultan Ahmed Al Jaber, CEO of the United Arab Emirates' Abu Dhabi National Oil Company, to lead the United Nations Climate Change Conference, also known as COP28, later this year.

"Surging temperatures demand a surge in action," said Guterres. "Leaders must turn up the heat now for climate solutions. We can still avoid the worst of climate chaos—and we don't have a moment to lose."