Have we exceeded 1.5°C of warming in 2024? It depends on who you ask

Today, six climate agencies from around the world confirmed what we knew was coming: Earth once again experienced its hottest year on record.

But whether or not the temperature has exceeded 1.5°C above the pre-industrial average depends on which climate agency you look at.

According to the European Union’s Copernicus Climate Change Service, 2024 was the warmest year on record since 1850, at 1.6°C above the pre-industrial average (1850-1900). It surpassed 2023 as the hottest year on record, which was 1.48°C warmer than the pre-industrial average.

However, according to NASA, 2024 was 1.47°C warmer than the pre-industrial average, hovering near 1.5°C.

The National Oceanic and Atmospheric Administration (NOAA) found that the temperature was 1.46 degrees Celsius warmer.

Berkeley Earth, a nonprofit climate analysis organization, also found that 2024 was 1.62 degrees Celsius warmer than the pre-industrial average.

The numbers vary between agencies because of the way climate agencies collect historical data.

However, the World Meteorological Organization looked at all these analyses, as well as those from the UK Met Office and the Japan Meteorological Agency, and found that we will “most likely” exceed 1.5°C of warming in 2024.

But what is agreed upon is that the past ten years have been the hottest on record.

Although this may be the first calendar year to exceed the 1.5°C threshold set in Paris AgreementThis does not mean that we have violated this agreement. This threshold – a pledge by 195 countries to keep global warming below 1.5 degrees Celsius of the pre-industrial average – applies to many years in which the Earth’s temperature is consistently higher than that, not just one or two years.

This also does not mean that there is no hope of preventing temperature increases from exceeding this target. As climate scientists often say, “Every part of the grade is important“.

This is not the first 12-month period in which warming has risen above this threshold. From mid-2023 to mid-2024, the planet was 1.5 degrees Celsius warmer. It’s just that it didn’t happen within a calendar year.

Does 1.5 really matter?

While there may be some disagreement about the exact degree of temperature rise — in just hundredths of a degree — the message is the same: the Earth is getting warmer.

“I think what we can say is that 2024 will likely exceed the 1.5 limit,” said Gavin Schmidt, director of NASA’s Goddard Institute for Space Studies. “However, the effects that we see, if it’s like 1.48 or 1.52 or 1.6, they’re pretty similar.”

“We’re seeing increased rainfall intensity, we’re seeing increased heatwaves, we’re seeing sea levels rising. All of these things don’t really depend on the small details of that last decimal point,” he said. Schmidt.

According to the World Weather Attribution (WWA), climate-related disasters contributed to the deaths of at least 3,700 people and the displacement of millions in 26 weather events studied in 2024.

In its December report, WWA noted that “these were just a small portion of the 219 events that met our criteria, used to determine the most impactful weather events. The total number of people killed in extreme weather events likely exacerbated by climate “The change this year is in the tens or hundreds of thousands.”

When will we know that we have crossed the threshold of the Paris Agreement?

While 2024 started with high temperatures, fueled by El Niño — a natural, cyclical warming phenomenon in a region of the Pacific Ocean, which, along with the atmosphere, can lead to higher global temperatures — that is not the case for 2025.

“This year, 2025, we’re going to start off with kind of a moderate down year, kind of on the cool side,” Schmidt said. “So the contrast between 2025 and 2024 will be: we started at a cooler level. So we expect 2025 to be cooler than 2024 but maybe not by much,” he added.

Instead of El Niño, we started with a warning of La Niña, which could cause global temperatures to cool slightly.

Even if 2025 brings a colder year, the trend is for Earth’s temperature to move steadily upward.

But knowing when we exceed the 1.5 degrees Celsius threshold stipulated in the Paris Agreement is difficult.

“This has generally been interpreted, including the latest (Intergovernmental Panel on Climate Change) report, as pre-industrial meaning 1850 to 1900, and achieving the target means the 20-year average exceeds 1.5 degrees,” Zeke said. Hausfather, a research scientist at Berkeley land.

“The problem with that definition, of course, is that we won’t actually know when we have exceeded 1.5 degrees until 10 years after we have exceeded 1.5 degrees, which is not a very useful definition,” he said.

But Hausfather noted that there are climate scientists trying to come up with a better way to make this decision sooner.

However, he said, “We will likely exceed 1.5 degrees strongly in the next five to 10 years.”

And while it may be tiring to hear that another year will be in the record books no matter where it is, Schmidt said there’s a reason for that.

“It’s the same story every year or so, because the long-term trends are driven by our fossil fuel emissions, and they haven’t stopped,” he said. “Until they stop, we’re just going to keep having the same conversation. Do I sound like a broken record? Yes, I do, because we keep breaking records.”

For Hausfather, he’s also concerned about the continuing upward trend in temperatures.

“The climate is an angry monster,” he said. “We should stop poking him with sticks.”