This is a climate era when even the most ferocious records are bound to be broken.

Scientists in Europe Friday confirmed that 2024 had been the hottest year on record — and the first to surpass a dangerous warming threshold of 1.5 degrees Celsius (2.7 degrees Fahrenheit) that nations had pledged not to cross.

But even as experts described the year as unprecedented, they acknowledged that it would ultimately become just one more marker in an upward warming trajectory causing havoc on a growing scale.

A stop sign warns tourists of extreme heat at Badwater Basin in July 2024, in Death Valley National Park, Calif. Daniel Jacobi II/Las Vegas Review-Journal via AP

“As long as people keep burning fossil fuels, this will only get worse,” said Friederike Otto, who leads a scientific group, World Weather Attribution, that assesses the role of climate change in amplifying extreme weather events.

In 2024, according to data from the European Union’s Copernicus Climate Change Service, temperatures reached 1.6 degrees Celsius above preindustrial levels. Aside from Australia and Antarctica, every continent experienced its warmest year on record. So too did sizable parts of the ocean.

It is the second consecutive year in which the world has set a temperature record. In 2023, the arrival of El Niño — a natural phenomenon that is known to boost global temperatures — brought a jolt of warming much earlier than scientists had expected, with a temperature 1.48 degrees Celsius above preindustrial levels. Then in 2024, temperatures predictably remained elevated in the wake of the fading El Niño, and scientists are debating what other factors may have contributed to the margin of record warmth.

Projections suggest that 2025 might not be as hot as the past two years but that it will probably rank in the top five warmest years on record. Despite the year-to-year fluctuations, the general trend is obvious, as is the cause: the emission of greenhouse gases, primarily from fossil fuels. Each of humanity’s 10 hottest years have come over the past decade. At the time, 2016 was seen as an unprecedented scorcher — what one climate scientist called a “wake-up call.” Just nine years later, 2016 is now looking “decidedly cool,” said Adam Scaife, the head of long-range prediction at Britain’s Met Office.

In 2024, so many heat-related events caused death and damage that it was hard to keep up.

It was a year in which an estimated 1,300 religious pilgrims died under 120-degree Saudi Arabian heat. It was a year when a smoke plume stretched diagonally across nearly all of wildfire-stricken South America, when heat-exhausted howler monkeys fell dead out of trees in Mexico, and when the hottest place on earth — California’s Death Valley — registered its hottest month ever.

The heat also transformed the oceans. Marine heat waves, expansive blobs of unusual oceanic heat, covered parts of all ocean basins during the year, reaching extreme levels in the tropical Atlantic, North Pacific and western Indian Ocean. That fostered an atmosphere capable of holding more moisture, which in turn led to one of the year’s most pronounced patterns: intense storms and flooding.

Dubai, a hub of luxury in the arid Persian Gulf desert, was hit by a year’s worth of rain in a single day, flooding highways and grounding flights. For the first time on record, four tropical cyclones formed simultaneously in the western Pacific in November — displacing hundreds of thousands of people in the Philippines. In Spain, an extreme rainfall pattern fed on unusually warm Mediterranean waters, leading to the deadliest floods in a single European country since 1967.

“It was like a tsunami,” said Mario Martinez, a Valencia barbershop owner, who watched the floodwaters break through the glass windows of his shop.

He escaped the rising waters by hopping on a car that had gone into the storefront, and then jumping to a second-floor balcony.

“First, you’re just grateful to be alive,” said Martinez, 50. “And then you realize what has happened and how much it has ruined you.” He said the flood threw him back by “20 or 30 years.” He spent weeks in cleanup mode, and when he reopened a month later — still with mud caking the walls — his was the only remaining business on the block.

WILL THE HEAT CONTINUE?

Though the world broke the 1.5-degree Celsius threshold in 2024, that doesn’t mean the planet has formally breached the most ambitious target set in the Paris agreement. It will take a much longer span for scientists to make that determination.

That’s partly because there are many variables that make some years hotter than others. One of those variables is the natural El Niño-Southern Oscillation, based on shifts in ocean trade winds, which can influence global weather patterns. During El Niño periods, sea surface temperatures across the middle of the Pacific Ocean tend to be higher than average. During La Niña periods, they tend to be cooler.

Right now, cool water in the equatorial Pacific signals that La Niña has developed. But it is expected to be short-lived.

New climate model projections show the cool water in the Pacific eroding and giving way to warmer-than-average seas by the middle part of 2025.

Meanwhile, warmer-than-average seas are predicted to continue across most of the rest of the planet.

This suggests that the planet will have little, if any, reprieve from record warmth in the months ahead — which could be exacerbated further if an El Niño develops later in the year. El Niño events are known for their warming effect, as heat that builds up along the equator spreads outward.

There is some question about what drove the record warmth of 2023 and 2024, besides the emergence of a strong El Niño climate pattern. Scientists have explored contributions from a 2022 volcanic eruption that spewed water vapor into the atmosphere, a spike in solar activity sending more energy toward Earth, and reductions in air pollution around the world, which allowed more sunlight to reach the planet’s surface.

They found a mix of influences. But a full understanding is still lacking, said Gavin Schmidt, director of the NASA Goddard Institute for Space Studies.

That makes it more difficult to predict what trajectory temperatures could take in the years ahead, since some warming factors could be temporary, while others could continue adding to the warmth, said Nick Dunstone, a fellow at the Met Office.

“It really depends what the driver is, as to what happens next,” Dunstone said.

A HIDDEN TOLL

Despite the planetary alarm bells, it was a brutal year for environmental diplomacy. The right-wing shift in many countries, coupled with the victory of former president Donald Trump in the United States, widened divides over who is responsible for climate change and how to deal with it. Several end-of-year events on environmental issues either derailed or failed to make substantial progress. Saudi Arabia used its veto power to push back against the global phaseout of fossil fuels. Wealthy nations offered only a fraction of the money needed by poorer countries to handle the escalating costs of climate change.

And indeed, in 2024, extreme events left the greatest toll in places least equipped to handle it.

Sudan, torn apart by war, saw flooding that inundated crops and displaced scores who had already fled once because of conflict. Across Chad, Mali and Nigeria, extreme rains killed more than 1,000 and upended the lives of people such as Babakura Bukar, who fled his home when the rainfall started and then returned to it in a rented canoe.

The flooding was so vast that in the aftermath, his neighborhood, in the Nigerian city of Maiduguri, resembled a lake.

Bukar paddled toward his home and felt his heart drop. The outer fence of his property had collapsed. His furniture and most of his electronics were destroyed. He managed to salvage a solar panel from the rooftop.

“It was a nightmare,” said Bukar, 58, a retired journalist.

Even several months later, he is still living with his family in the guesthouse of a friend.

He received $200 in government assistance, he said. But rebuilding his home will cost about $6,000, he estimated.

“And I don’t even think I am halfway done,” he said.