A team of 60 international scientists report that by early 2028 society will have emitted enough greenhouse gases that the Earth will be pretty much locked into hitting the internationally agreed upon preferred limit for global warming

WASHINGTON — Humans are on track to release so much greenhouse gas in less than three years that a key threshold for limiting global warming will be nearly unavoidable, according to a study to be released Thursday.

The report predicts that society will have emitted enough carbon dioxide by early 2028 that crossing an important long-term temperature boundary will be more likely than not. The scientists calculate that by that point there will be enough of the heat-trapping gas in the atmosphere to create a 50-50 chance or greater that the world will be locked in to 1.5 degrees Celsius (2.7 degrees Fahrenheit) of long-term warming since preindustrial times. That level of gas accumulation, which comes from the burning of fuels like gasoline, oil and coal, is sooner than the same group of 60 international scientists calculated in a study last year.

“Things aren’t just getting worse. They’re getting worse faster,” said study co-author Zeke Hausfather of the tech firm Stripe and the climate monitoring group Berkeley Earth. “We’re actively moving in the wrong direction in a critical period of time that we would need to meet our most ambitious climate goals. Some reports, there’s a silver lining. I don’t think there really is one in this one.”

That 1.5 goal, first set in the 2015 Paris agreement, has been a cornerstone of international efforts to curb worsening climate change. Scientists say crossing that limit would mean worse heat waves and droughts, bigger storms and sea-level rise that could imperil small island nations. Over the last 150 years, scientists have established a direct correlation between the release of certain levels of carbon dioxide, along with other greenhouse gases like methane, and specific increases in global temperatures.

In Thursday’s Indicators of Global Climate Change report, researchers calculated that society can spew only 143 billion more tons (130 billion metric tons) of carbon dioxide before the 1.5 limit becomes technically inevitable. The world is producing 46 billion tons (42 billion metric tons) a year, so that inevitability should hit around February 2028 because the report is measured from the start of this year, the scientists wrote. The world now stands at about 1.24 degrees Celsius (2.23 degrees Fahrenheit) of long-term warming since preindustrial times, the report said.

The report, which was published in the journal Earth System Science Data, shows that the rate of human-caused warming per decade has increased to nearly half a degree (0.27 degrees Celsius) per decade, Hausfather said. And the imbalance between the heat Earth absorbs from the sun and the amount it radiates out to space, a key climate change signal, is accelerating, the report said.

“It’s quite a depressing picture unfortunately, where if you look across the indicators, we find that records are really being broken everywhere,” said lead author Piers Forster, director of the Priestley Centre for Climate Futures at the University of Leeds in England. “I can’t conceive of a situation where we can really avoid passing 1.5 degrees of very long-term temperature change.”

The increase in emissions from fossil-fuel burning is the main driver. But reduced particle pollution, which includes soot and smog, is another factor because those particles had a cooling effect that masked even more warming from appearing, scientists said. Changes in clouds also factor in. That all shows up in Earth’s energy imbalance, which is now 25% higher than it was just a decade or so ago, Forster said.

Earth’s energy imbalance “is the most important measure of the amount of heat being trapped in the system,” Hausfather said.

Earth keeps absorbing more and more heat than it releases. “It is very clearly accelerating. It’s worrisome,” he said.

The planet temporarily passed the key 1.5 limit last year. The world hit 1.52 degrees Celsius (2.74 degrees Fahrenheit) of warming since preindustrial times for an entire year in 2024, but the Paris threshold is meant to be measured over a longer period, usually considered 20 years. Still, the globe could reach that long-term threshold in the next few years even if individual years haven’t consistently hit that mark, because of how the Earth’s carbon cycle works.

That 1.5 is “a clear limit, a political limit for which countries have decided that beyond which the impact of climate change would be unacceptable to their societies,” said study co-author Joeri Rogelj, a climate scientist at Imperial College London.

The mark is so important because once it is crossed, many small island nations could eventually disappear because of sea level rise, and scientific evidence shows that the impacts become particularly extreme beyond that level, especially hurting poor and vulnerable populations, he said. He added that efforts to curb emissions and the impacts of climate change must continue even if the 1.5 degree threshold is exceeded.

Crossing the threshold “means increasingly more frequent and severe climate extremes of the type we are now seeing all too often in the U.S. and around the world — unprecedented heat waves, extreme hot drought, extreme rainfall events, and bigger storms,” said University of Michigan environment school dean Jonathan Overpeck, who wasn’t part of the study.

Andrew Dessler, a Texas A & M University climate scientist who wasn’t part of the study, said the 1.5 goal was aspirational and not realistic, so people shouldn’t focus on that particular threshold.

“Missing it does not mean the end of the world,” Dessler said in an email, though he agreed that “each tenth of a degree of warming will bring increasingly worse impacts.”

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Earth recorded its hottest year ever in 2024, with such a big jump that the planet temporarily passed a major climate threshold, weather monitoring agencies announced Friday.

It’s the first time in recorded history that the planet was above a hoped-for limit to warming for an entire year, according to measurements from four of the six teams. Scientists say if Earth stays above the threshold long-term, it will mean increased deaths, destruction, species loss and sea level rise from the extreme weather that accompanies warming.

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And that would come on top of a year of deadly climate catastrophes — 27 billion-dollar disasters in the U.S. alone in 2024 — and as 2025 begins with devastating wildfires in southern California.

Last year’s global average temperature easily passed 2023’s record heat and kept going. It surpassed the long-term warming limit of 1.5 degrees Celsius (2.7 degrees Fahrenheit ) since the late 1800s that was called for by the 2015 Paris climate pact, according to the European Commission’s Copernicus Climate Service, the United Kingdom’s Meteorology Office, Japan’s weather agency and the private Berkeley Earth team.

Only two U.S. government agencies had Earth below that 1.5 mark. The National Oceanic and Atmospheric Administration and NASA had last year at 1.46 degrees Celsius (2.63 degrees Fahrenheit) and 1.47 degrees Celsius (2.65 degrees Fahrenheit).

The Copernicus team calculated 1.6 degrees Celsius of warming, Japan 1.57 and the British 1.53. Berkeley Earth — originally funded by a climate change skeptic — came in the hottest at 1.62 degrees.

“The primary reason for these record temperatures is the accumulation of greenhouse gases in the atmosphere” from the burning of coal, oil and gas, said Samantha Burgess, strategic climate lead at Copernicus. “As greenhouse gases continue to accumulate in the atmosphere, temperatures continue to increase, including in the ocean, sea levels continue to rise, and glaciers and ice sheets continue to melt.”

Last year was the hottest year for the United States, NOAA said. It was not only the hottest in recordkeeping that goes back to 1850, but likely the hottest for the planet in 125,000 years, Burgess said.

“There’s nothing to indicate that it won’t continue,” NOAA monitoring chief Russ Vose said Friday. “When there’s more heat in the system that has a cascading effect on other parts of the system. Sea level goes up. Warmer air can hold more moisture which tends to equate to more extreme storms. There’s a lot of impacts that go along with a warmer world.”

By far the biggest contributor to record warming is the burning of fossil fuels, several scientists said. A temporary natural El Nino warming of the central Pacific added a small amount and an undersea volcanic eruption in 2022 ended up cooling the atmosphere because it put more reflecting particles in the atmosphere as well as water vapor, Burgess said.

Alarm bells are ringing

“Climate-change-related alarm bells have been ringing almost constantly, which may be causing the public to become numb to the urgency, like police sirens in New York City,” Woodwell Climate Research Center scientist Jennifer Francis said. “In the case of the climate, though, the alarms are getting louder, and the emergencies are now way beyond just temperature.”

Comparing it to a car’s dashboard warning light, University of Georgia meteorology professor Marshall Shepherd said, “Hurricane Helene, floods in Spain and the weather whiplash fueling wildfires in California are symptoms of this unfortunate climate gear shift.”

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There were 27 weather disasters in the United States that caused at least $1 billion in damage, just one fewer than the record set in 2023, according to NOAA. The U.S. cost of those disasters was $182.7 billion. Hurricane Helene was the costliest and deadliest of the year with at least 219 deaths and $79.6 billion in damage.

“In the 1980s, Americans experienced one billion-plus weather and climate disaster on average every four months,” Texas Tech climate scientist Katharine Hayhoe said in an email about NOAA’s inflation-adjusted figures. “Now, there’s one every three weeks —and we already have the first of 2025 even though we’re only 9 days into the year.”

World breaches major threshold

Scientists were quick to point out that the 1.5 goal is for long-term warming, now defined as a 20-year average. Warming since pre-industrial times over the long term is now at 1.3 degrees Celsius (2.3 degrees Fahrenheit).

“The 1.5 degree C threshold isn’t just a number — it’s a red flag. Surpassing it even for a single year shows how perilously close we are to breaching the limits set by the Paris Agreement,” Northern Illinois University climate scientist Victor Gensini said in an email. A 2018 massive United Nations study found that keeping Earth’s temperature rise below 1.5 degrees Celsius could save coral reefs from going extinct, keep massive ice sheet loss in Antarctica at bay and prevent many people’s death and suffering.

Francis called the threshold “dead in the water.”

Burgess called it extremely likely that Earth will overshoot the 1.5-degree threshold, but called the Paris Agreement “extraordinarily important international policy” that nations around the world should remain committed to.

More warming is likely

European and British calculations figure with a cooling La Nina instead of last year’s warming El Nino, 2025 is likely to be not quite as hot as 2024. They predict it will turn out to be the third-warmest. However, the first six days of January — despite frigid temperatures in the U.S. East — averaged slightly warmer and are the hottest start to a year yet, according to Copernicus data.

Scientists remain split on whether global warming is accelerating.

There’s not enough data to see an acceleration in atmospheric warming, but the heat content of the oceans seem to be not just rising but going up at a faster rate, said Carlo Buontempo, Copernicus’ director.

“We are facing a very new climate and new challenges — climate challenges that our society is not prepared for,” Buontempo said.

This is all like watching the end of “a dystopian sci-fi film,” said University of Pennsylvania climate scientist Michael Mann. “We are now reaping what we’ve sown.”

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Open this photo in gallery: Tourists shade themselves with an umbrella as they walk in front of the Parthenon at the ancient Acropolis in central Athens, on June 12.Petros Giannakouris/The Associated Press

We have arrived at the place where climate scientists say we shouldn’t be.

For the first time, the world’s average annual temperature has exceeded 1.5 degrees Celsius above preindustrial levels during a calendar year.

A report released Thursday by Europe’s Copernicus Climate Change Service show that not only was 2024 the hottest year ever measured – easily beating a record set just 12 months earlier – but it marks the planet’s entry into a heat regime that the Paris climate agreement explicitly aims to avoid.

People need scarcely look for signs that rising temperatures are having their predicted effect. Fires raging in the suburbs of Los Angeles this week are just the latest example of a series of extreme weather events that have racked up damage and death around the globe.

“These high global temperatures, coupled with record global atmospheric water vapour levels in 2024, meant unprecedented heatwaves and heavy rainfall events, causing misery for millions of people,” Samantha Burgess, the service’s deputy director, said in a statement accompanying the release.

If there is a caveat, it is that the global figure represents a combination of factors. Climate change spurred by fossil-fuel use is the primary driver of the warming. But the first part of last year was also affected by the tail end of the previous year’s El Nino, a Pacific Ocean phenomenon that can raise temperatures globally.

The European organization also updated its running five-year average, which offers a more smoothed-out view of what the global temperature is doing. This puts the planet at about 1.3 degrees warmer than it was between 1850 and 1900. But it still shows 2024 as the warmest year yet. And there is little doubt about where things are heading.

“It’s basically a clear signal that we’ve arrived or we’re very close to arriving at the threshold we were trying to stay under,” said Frédéric Fabry, a meteorologist and professor at McGill University in Montreal. “In a few years we will hit that 1.5-degree warming regularly.”

While such shifts may seem modest when expressed as a global average, they disguise the increasing frequency with which extreme weather is affecting life around the world.

“Exceptional events that we’re not equipped to deal with because they are so rare are becoming more common – and we’re starting to see it,” Dr. Fabry said.

A list of extreme weather events Canada has seen over the past 12 months includes serious flooding in Toronto and Montreal, a record-breaking hailstorm in Calgary and a devastating wildfire that consumed a third of Jasper, Alta.

On Tuesday, Environment and Climate Change Canada released its own look back over the previous year and noted that temperatures were “above normal” in every region of the country.

Canada is a signatory to the 2015 Paris Agreement, an international treaty that was established with the goal of keeping global warming “well below” two degrees while pursuing efforts to limit the temperature increase to 1.5 degrees.

But Canada has struggled for years to meet its own climate goals in support of the agreement. Indeed, the politics of the moment suggests the country could soon be heading in the opposite direction, potentially following the United States, where president-elect Donald Trump has consistently voiced support for expanding domestic fossil-fuel production and dismantling climate measures enacted by the Biden administration.

And while the fires in Los Angeles offer a stark warning about where such a policy is projected to lead, the burden of climate change is now unequivocally being felt around the planet.

The European release noted that at maximum last year, 44 per cent of the globe was affected by “strong to extreme heat stress.” The total amount of water vapour in the atmosphere also reached a new record value, with high humidity levels contributing to the health risk of high heat and the likelihood of extreme precipitation events.

“It is clear we are now living in a very different climate from that which our parents and our grandparents experienced,” said Dr. Burgess during an online press briefing.

The conclusions of the report were confirmed by the UK MET Office in a separate release on Thursday. Similar results are expected from a briefing scheduled for Friday by NASA and the National Oceanic and Atmospheric Administration.

This year won’t just be the hottest on record—it could be the first to surpass 1.5 degrees Celsius. The Paris climate accord aims to keep warming below that level when looking over multiple years

Editor’s Note (12/9/24): This story is being republished after the Copernicus Climate Change Service released global temperature data from November. The data confirmed that it is “effectively certain” that 2024 will be the warmest year on record and will surpass 1.5 degrees Celsius above preindustrial temperatures.

It is “virtually certain” that 2024 will be the first year to be more than 1.5 degrees Celsius (2.7 degrees Fahrenheit) hotter than in the preindustrial era, before heat-trapping fossil fuels began accumulating in the atmosphere, the European Union’s Copernicus Climate Change Service (C3S) announced today.

These dubious distinctions mean 2024 will surpass the remarkable record annual temperatures set just last year, one of the clearest markers of the unfolding planetary climate catastrophe. “This marks a new milestone in global temperature records and should serve as a catalyst to raise ambition for the upcoming Climate Change Conference, COP29,” Samantha Burgess, deputy director of C3S, said in a news release.

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Amanda Montañez; Source: Copernicus Climate Change Service (data)

The likelihood of that happening is placed in doubt, though, with the news that former U.S. President Donald Trump has won reelection. Trump has promised to increase U.S. fossil-fuel production and to weaken federal rules that limit the emissions of planet-warming greenhouse gases. Over the past four years, the Biden-Harris administration took the most action to address the climate crisis of any U.S. presidential administration—primarily through enacting the Inflation Reduction Act. The continuation of funding for renewable energy and other climate-related provisions in that and other laws is now up in the air.

Trump has also said he will once again remove the U.S. from the Paris climate accord, under which countries agreed to try to limit warming to under 1.5 degrees C and “well under” 2 degrees C (3.6 degrees F). Those limits would not officially be reached until the global temperature averaged those temperatures over multiple years. The world will see several individual years periodically surpass those milestones before such long-term averages are achieved.

Already several months have surpassed the 1.5 degree C mark. This October was 1.65 degrees C (3 degrees F) above the preindustrial period, generally defined as the late 19th century.

Climate scientists have said these temperature records are overwhelmingly the result of ever rising levels of greenhouse gases such as carbon dioxide. The World Meteorological Organization (WMO) confirmed last month that CO 2 reached a record high of 420 parts per million last year. CO 2 levels in the preindustrial period were around 280 ppm.

Thousands of climate studies have shown that the more—and faster—the world can bring emissions down to zero, the more humanity can avoid the harmful impacts of warming, such as harsher and more frequent heat waves, larger destructive floods, and crop damage that can drive up food prices.

Firefighters work on the zone of a forest fire in the Valparaiso region in Chile on Feb. 3, 2024. Javier Torres | Afp | Getty Images

A weather arm of the United Nations on Wednesday warned that within the next five years, the world will likely surpass a critically important warming threshold, reinforcing the urgent need to slash planet-heating greenhouse gas emissions. In a landmark report timed to coincide with World Environment Day, the World Meteorological Organization said there is now an 80% chance that global average temperatures will exceed 1.5 degrees Celsius, or 2.7 degrees Fahrenheit, above pre-industrial levels for at least one year between 2024 and 2028. That prediction marks a stark change from 2015 when the WMO considered the prospect of temporarily overshooting 1.5 degrees Celsius close to zero. The 1.5-degree Celsius limit is the aspirational target of the landmark 2015 Paris Agreement, an international treaty on climate change. Scientists say that exceeding this temperature threshold over the long term will lead to increasingly frequent and catastrophic extreme weather events.

“We need an exit ramp off the highway to climate hell. And the truth is we have control of the wheel.” António Guterres United Nations Secretary-General

Even at current levels of global warming, there are already devastating climate change impacts. These include record-breaking heatwaves, extreme rainfall events and droughts, accelerating sea level rise and ocean heating and dramatic reductions in ice sheets and sea ice. “We are playing Russian roulette with our planet,” U.N. Secretary-General António Guterres said in a speech on Wednesday. “We need an exit ramp off the highway to climate hell. And the truth is we have control of the wheel.” Guterres said that the battle to limit long-term temperatures to 1.5 degrees Celsius will be won or lost in the 2020s under the watch of today’s world leaders.

U.N. Secretary-General Antonio Guterres delivers a special address on climate action at the American Museum of Natural History in New York City on World Environment Day, June 5, 2024. Charly Triballeau | Afp | Getty Images

Speaking at the American Museum of Natural History in New York City, Guterres called for much more ambitious action to tackle the climate crisis ahead of the G7 summit in Italy from June 13 to June 15. “All depends on the decisions those leaders take — or fail to take — especially in the next 18 months. It’s climate crunch time,” he added.

‘Sounding the alarm’

Extreme heat is fueled by the climate crisis, which is chiefly driven by the burning of fossil fuels. The WMO said in its report that global average temperatures for each year between 2024 and 2028 were expected to be between 1.1 degrees Celsius and 1.9 degrees Celsius higher than the 1850 to 1900 baseline. The agency said there is a roughly 50/50 chance that global average temperatures over the entire five-year period will exceed 1.5 degrees Celsius compared with the pre-industrial era — up from a 32% likelihood from last year’s report assessing the period from 2023 to 2027. At least one of the years through 2028 will likely set a new temperature record, the report said, which would beat 2023, currently the hottest year on record.

A couple sits on Tourkovounia Hill in Athens as southerly winds carry waves of Saharan dust, April 23, 2024. Angelos Tzortzinis | Afp | Getty Images