4 hottest days ever observed raise fears of a planet nearing ‘tipping points’

By the end of the week — which saw the four hottest days ever observed by scientists — dozens had been killed in the raging floodwaters and massive mudslides triggered by Typhoon Gaemi. Half of Jasper was reduced to ash. And about 3.6 billion people around the planet had endured temperatures that would have been exceedingly rare in a world without burning fossil fuels and other human activities, according to an analysis by scientists at the group Climate Central.

These extraordinary global temperatures marked the culmination of an unprecedented global hot streak that has stunned even researchers who spent their whole careers studying climate change.

Since last July, Earth’s average temperature has consistently exceeded 1.5 degrees Celsius (2.7 degrees Fahrenheit) above preindustrial levels — a short-term breach of a threshold that scientists say cannot be crossed if the world hopes to avoid the worst consequences of planetary warming.

This “taste” of a 1.5-degree world showed how the natural systems that humans depend on could buckle amid soaring temperatures, said Johan Rockström, director of the Potsdam Institute for Climate Impact Research in Germany. Forests showed less ability to pull carbon out of the atmosphere. Sea ice around Antarctica dwindled to near record lows. Coral bleaching became so extreme scientists had to change their scale for measuring it.

Even as scientists forecast an end to the current record-breaking stretch, they warn it may prove difficult for parts of the planet to recover from the heat of the past year.

“The extreme events that we are now experiencing are indications of the weakening resilience of these systems,” Rockström said. “We cannot risk pushing this any further.”

This week’s broken records come on the heels of 13 straight months of unprecedented temperatures — fueled in part by the planet’s shift into an El Niño climate pattern, which tends to warm the oceans, as well as pollution from burning coal, oil and gas.

The warming neared its apex on Sunday, when data from the Copernicus Climate Change Service, the European climate monitor, showed the global average temperature edging out a record set a little over a year earlier.

But the new benchmark stood for only 24 hours, with Monday hitting a historic 17.16 degrees Celsius (62.89 degrees Fahrenheit). Tuesday was the second hottest on record, and Wednesday tied Sunday as the third warmest.

Though these numbers may not seem extreme, they are the average of thousands of data points taken from the Arctic to the South Pole, in places that are experiencing winter as well as those in the midst of summer. The preliminary data was generated using a sophisticated type of analysis that combines global weather observations with a state of the art climate model — a method that outside researchers said Copernicus’s is highly reliable.

The world’s oceans are also awash in historic heat. Copernicus data shows that the waters around Taiwan are 2 to 3 degrees Celsius (3.6 to 5.4 degrees Fahrenheit) hotter than normal, helping to fuel Typhoon Gaemi’s devastation. Research shows that higher ocean temperatures give more power to tropical cyclones, while a warmer atmosphere can hold more water — and thus produce more rain.

Meanwhile, almost 2,000 weather stations around the planet notched new daily high temperature records over the last seven days, according to the National Centers for Environmental Information.

Although scientists have not yet quantified the role of warming in all of this year’s extreme events, there is abundant evidence that heat waves, storms and fires are made more frequent and intense because of climate change.

“We are running out of metaphors” to describe the unrelenting pace and scale at which the world is breaking records, Copernicus director Carlo Buontempo said.

Sometimes, he said, he feels like the planet’s temperature is a helium balloon drifting inevitably upward. All he can do is stand below and say, “Look, it is higher.”

Scientists have estimated Earth’s average temperature based on observations dating to 1850, and now measure it by pulling data from more than 20,000 land-based stations as well as readings from ships and buoys around the globe.

To convey the severity of Earth’s current heat, other researchers have turned to the planet’s past. By studying tree rings, lake sediments and other records of the ancient climate, paleoclimate researchers have determined that the world is likely now warmer than it has been in more than 100,000 years, since before the start of the last Ice Age.

Humanity faces conditions unlike anything our species has known before. According to a Climate Central analysis of the five-day period ending Friday, almost half of the planet experienced at least one day of “exceptional heat” — temperatures that would have been rare or even impossible in a world without climate change.

United Nations Secretary General António Guterres on Thursday called for improved warning systems, stronger worker protections and other policies to protect people from these scorching temperatures.

“Extreme temperatures are no longer a one day, one week or one month phenomenon,” he said at a news conference.

Buontempo expects that Earth’s record-breaking streak may soon end. The National Oceanic and Atmospheric Administration last month declared an official end to the El Niño, reflecting cooling conditions in the tropical Pacific Ocean. The end of summer in the Northern Hemisphere — where most of the world’s land is — also tends to bring down the planet’s overall temperature.

Yet the unprecedented amount of heat-trapping carbon in Earth’s atmosphere — which is at its highest level in more than 3 million years — will mean that even without El Niño, the world remains perilously warm. Many researchers project that 2024 will end as the hottest year on record, exceeding the benchmark set in 2023.

“The fluctuations we’re seeing are relatively modest on top of a very large, decades-long warming trend,” said climate scientist Kim Cobb, director of the Institute at Brown University for Environment and Society. “We’re dancing about a climate average that is very dangerous for communities and ecosystems around the world.”

The worst of this week’s heat was concentrated in Antarctica, where temperatures were as much as 12 degrees Celsius (21.6 degrees Fahrenheit) above normal.

Lynne Talley, a researcher at the Scripps Institution of Oceanography at the University of California at San Diego, said that anomaly is likely the product of strong winds pushing warm air onto the continent. Those conditions will make it more difficult for the ocean to freeze during what is usually the prime time for sea ice formation.

“It seems like global warming is finally catching up with Antarctica, and that’s pretty frightening,” she said.

The amount of sea ice around Antarctica is already at its second lowest level on record for this time of year — coming in just behind last July. After losing an unprecedented amount of ice cover during the 2023 melt season, Talley said, the region has been unable to rebound.

To Rockström, the decline in Antarctic sea ice is one indication of how the recent global heat may be undermining the planet’s ability to buffer against some of climate change’s worst effects. Sea ice helps keep the poles cool by reflecting much of the sunlight that hits it back into space. When the ice melts, and the sun’s rays can reach the dark open ocean, their energy is absorbed by the planet.

He also pointed to a new analysis that found the wilting and burning forests of the Amazon, Asia and Canada had lost much of their ability to absorb the excess carbon dioxide produced by human activities. The research, which has not yet been published in a peer-reviewed journal, focused on data from 2023 — meaning scientists are still unsure whether the finding represents a short-term blip or a more permanent shift.

This year, the world’s forests are struggling once again. As of Wednesday, Canadian authorities were battling 310 uncontrolled wildfires, including the blaze that ravaged the town of Jasper. Trees turned to tinder by weeks of extreme heat are fueling a fast-moving fire in Northern California. The Amazon is bracing for a second consecutive year of an extreme drought that studies show is fueled by climate change.

Robert Rohde, chief scientist for the climate data nonprofit Berkeley Earth, called these extreme events “suggestive” of what will happen to the planet if global temperatures consistently exceed 1.5 degrees Celsius of warming — something that researchers project will occur in the early 2030s.

Studies indicate that crossing that threshold could trigger irreversible changes in major Earth systems: the collapse of the Greenland ice sheet, complete loss of tropical coral reefs, abrupt thawing of some permafrost.

What the world is seeing now, Rockström said, is a “worrying sign of potentially approaching tipping points.”

And as long as people continue adding carbon to the atmosphere, Cobb said, disasters will continue to happen and records will continue to fall.

“It’s a Russian roulette wheel of climate devastation,” she said. “Whether it’s going to be your community in the line of a hurricane, or your city is going to have a heat wave. The threat is here and it’s now.”