2024 was the hottest year on record, breaching a critical climate goal and capping 10 years of unprecedented heat

By Laura Paddison, CNN

(CNN) — It’s official: 2024 was the hottest year on record, breaking the previous record set in 2023 and pushing the world over a critical climate threshold, according to new data from Europe’s climate monitoring agency Copernicus.

Last year was 1.6 degrees hotter than the period before humans began burning large amounts of fossil fuels, Copernicus found. It makes 2024 the first calendar year to breach the 1.5-degree limit countries agreed to avoid under the Paris climate agreement in 2015.

Scientists are much more concerned about breaches over decades, rather than single years — as above that threshold humans and ecosystems may struggle to adapt — but 2024’s record “does mean we’re getting dangerously close,” said Joeri Rogelj, a climate professor at Imperial College London.

The Copernicus analysis points to a slew of climate records falling last year: The planet endured its hottest day on record in July; each month from January to June was the warmest such month on record; and levels of planet-heating pollution reached unprecedented highs.

Last year is part of a pattern of off-the-charts heat. Every single one of the world’s 10 hottest years happened in the last decade, according to Copernicus data.

Behind these statistics lies a huge toll. “Every fraction of a degree … brings more harm to people and ecosystems,” Rogelj said.

The extreme weather that swept the globe last year shows just how dangerous life in a warmer world already is.

Back-to-back hurricanes in the US, fueled by ultra-warm ocean temperatures, killed hundreds of people. In Spain, more than 200 people died in catastrophic floods. Amazon rivers fell to unprecedented lows during the region’s worst drought on record and the Philippines experienced an extraordinary typhoon season, with six in just 30 days.

The climate crisis played a role in all of these extreme events, according to scientific analyses.

Scientists are still trying to fully understand why global heat has been so extreme for the past two years.

The main driver is clear: the human-caused climate crisis, boosted by El Niño, a natural climate pattern that tends to have a warming influence, which began in 2023 and ended earlier this year. But it doesn’t explain all of the heat.

Scientists have also pointed to a recent drop in shipping pollution following regulations — a win for human health, but, in a cruel twist, this type of pollution also helps cool the planet by reflecting sunlight back into space.

The eruption of a huge underwater volcano in the South Pacific in 2022, which sent plumes of water vapor — a potent greenhouse gas — into the atmosphere may have also contributed.

Then there are the clouds. A December study found a dearth of sun-reflecting clouds over the ocean may be another factor.

Scientists believe it’s unlikely 2025 will be another record-breaking year. La Niña, a natural climate pattern that tends to have a global cooling influence, was declared Thursday.

“But people shouldn’t think that’s climate change hitting pause or plateauing,” said Paulo Ceppi, a climate scientist at Imperial College London. “A small dip doesn’t change the clear upward trajectory we’re on,” he added.

Scientists say the decades to come are likely to be hotter still as humans continue to burn planet-heating coal, oil and gas.

“The world doesn’t need to come up with a magical solution to stop things from getting worse in 2025,” said Friederike Otto, a climate scientist at Imperial College London. ‘We know exactly what we need to do to transition away from fossil fuels.”

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