2024’s Record-Breaking Heat Puts Earth at Dangerous Risk. Now What?

At midnight on December 31, Earth ended its hottest year in recorded history, scientists said on Friday. The previous hottest year was 2023. And the next one is coming soon: By continuing to burn vast amounts of coal, oil and gas, humanity has confirmed all of this.

Last year’s world record high temperature saw 104-degree-Fahrenheit spring heat waves close schools in Bangladesh and India. It showed the effects of warm ocean water on a tropical cyclone in the Gulf of Mexico and hurricanes in the Philippines. And it featured scorching summer and fall conditions that fueled Los Angeles this week’s most destructive wildfires in its history.

“We are facing a very new climate and new challenges, challenges that our society has not prepared for,” said Carlo Buontempo, director of the Copernicus Climate Change Service, a European Union monitoring agency.

But even within this progression of warmer years and ever-increasing risks to homes, communities and the environment, 2024 stood out in an otherwise unwelcome way. According to the World Meteorological Organization, it was the first year in which global temperatures averaged more than 1.5 degrees Celsius, or 2.7 degrees Fahrenheit, above what the planet experienced at the beginning of the industrial age.

For the past decade, the world has sought to avoid crossing this dangerous border. Countries included the goal in the 2015 Paris Agreement to combat climate change. “Keep 1.5 alive” was the mantra at the United Nations conferences.

However, we are here. Global temperatures will fluctuate somewhat, as they always do, which is why scientists often look at long-term average warming, not just one year.

But even at that rate, staying below 1.5 degrees looks increasingly out of reach, according to researchers who ran the numbers. Globally, despite hundreds of billions of dollars invested in clean energy technologies, carbon dioxide emissions hit a record high in 2024 and show no signs of abating.

A recent study published in the journal Nature concluded that the best humanity can hope for is 1.6 degrees of warming. In order to achieve this, countries will have to start reducing emissions at a pace that will disrupt political, social and economic performance.

But what if we started at the beginning?

“It was guaranteed that we would get to this point where the gap between the reality and the way we needed 1.5 degrees was so big it was ridiculous,” said David Victor, a professor of public policy at the University of California, San Diego.

The question now is what, if anything, should replace 1.5 as a habitat for nations’ climate ambitions.

“These high-level goals are the best compass,” said Dr. Victor. “It’s a reminder that if we don’t do more, we’re facing huge climate impacts.”

(Due to varying data sources and calculation methods, different scientific institutions independently arrived at slightly different estimates of last year’s warming. NASA and the National Oceanic and Atmospheric Administration said it was just under 1.5 degrees Celsius; Copernicus and the UK Met Office said that by combining these estimates with other , the World Meteorological Organization concluded that warming was 1.55 degrees agencies are in strong agreement on the rise in temperature over time long, and the fact that no year on record has been warmer than 2024.)

The 1.5-degree limit was not the difference between safety and destruction, between hope and despair. It was a number negotiated by governments trying to answer a big question: What is the highest global temperature — and the associated level of hazards, be it heat waves or wildfires or avalanches — that our communities should strive to avoid?

The result, as written in the Paris Agreement, was that nations would wish to hold warming to “below” 2 degrees Celsius while “pursuing efforts” to limit it to 1.5 degrees.

Even then, some experts called the latter goal absurd, because it required a deep and rapid reduction in emissions. Nevertheless, the United States, the European Union and other governments take it as a guideline for climate policy.

Christoph Bertram, an associate professor at the University of Maryland’s Center for Global Sustainability, said the urgency of the 1.5 target has prompted companies of all kinds — auto manufacturers, cement makers, electric utilities — to start thinking hard about what it would mean to stop. its release in the middle of the century. “I think that led to serious action,” said Dr. Bertram.

But the higher ambition of the 1.5 target also exposed deep fault lines between the nations.

China and India have never supported this policy, since it required them to stop using coal, gas and oil at a rate that they say will hinder their development. Rich countries struggling to reduce emissions began to squeeze funding from developing countries for economically beneficial fossil fuel projects. Some low-income countries feel that it was unfair to ask them to make climate sacrifices since it was the rich countries – not them – that produced most of the greenhouse gases that are now warming the world.

“The 1.5-degree goal has created a huge gap between rich and poor countries,” said Vijaya Ramachandran, director of energy and development at the Breakthrough Institute, an environmental research organization.

Costa Samaras, an environmental professor at Carnegie Mellon University, compared the warming goals to the guidelines of health officials about cholesterol. “We don’t set health goals for what is real or possible,” said Dr. Samaras. “We say: ‘This is good for you. You can’t get sick like this.’”

“If we were to say, ‘Well, 1.5 is probably out of the question, let’s put it at 1.75,’ it would give people the false assurance that 1.5 wasn’t that important,” said Dr. Samaras, who helped shape it. US climate policy from 2021 to 2024 at the White House Office of Science and Technology Policy. “It’s very important.”

Scientists assembled by the United Nations concluded that limiting warming to 1.5 degrees instead of 2 would protect tens of millions of people from exposure to life-threatening heat waves, water shortages and coastal flooding. It can mean the difference between a country with coral reefs and Arctic sea ice in the summer, and one without.

Each small increase in additional warming, whether it’s 1.6 degrees versus 1.5, or 1.7 versus 1.6, increases the risk. Inger Andersen, executive director of the United Nations Environment Program said: “Even if the world exceeds 1.5 degrees, and the chances of this happening increase every day, we must continue to fight” to bring pollution to zero as soon as possible.

Officially, the sun has not yet set on the 1.5 target. The Paris accord is still in effect, even as President-elect Donald J. Trump vows to withdraw the United States from it a second time. In the UN climate talks, the 1.5 talk has been much quieter compared to previous years. But it hasn’t gone away.

“With the right measures, 1.5 Celsius is still achievable,” said Cedric Schuster, the minister of natural resources and natural resources of the Pacific island of Samoa, at last year’s conference in Azerbaijan. Countries should “rise to the occasion with new, more ambitious policies,” he said.

To Dr. Victor of UC San Diego, it is ironic but predictable that governments keep talking this way about what seems like an unachievable goal. “No major political leader who wants to be taken seriously about climate wants to come out and say, ‘1.5 degrees is not possible.’ Let’s talk about achievable goals,” he said.

Still, eventually the world will need to have that conversation, says Dr. Victor. And it is not clear how it will go.

“It can be constructive, where we start to ask, ‘How much warming are we really in?’ And how do we deal with that?’” he said. “As toxic as it may seem, there’s a lot of political finger-pointing.”