After the puzzling warmth of Earth in 2023 and 2024, what could 2025 have in store?

Nicole Mortillaro · CBC News

· Posted: Jun 20, 2025 4:00 AM EDT | Last Updated: 5 minutes ago

After 12 consecutive months with temperatures 1.5 C above the 1850-1900 average, Earth's temperature has now fallen — thanks in part to the end of a natural cycle.

According to Berkeley Earth, a non-profit climate analysis organization, the global average temperature was 1.33 C above the pre-industrial average in the month of May, and the European Copernicus Climate Change Service (CCCS) found that the monthly average was 1.40 C above the pre-industrial average. (Climate agencies around the world use different methods to analyze global temperatures, hence the difference).

While that may seem like good news, the fact is that 2025 is still on track to be one of the top three warmest years on record, according to Zeke Hausfather from Berkeley Earth.

"With El Niño being firmly over, it is very unlikely at this point that 2025 is going to set a new record, but I still think it's the odds-on favourite to be the second-warmest on record, and it is virtually certain to be a top three warmest year," Hausfather said.

El Niño, a natural, cyclical warming in a region of the Pacific Ocean that, coupled with the atmosphere, can cause global temperatures to rise, began in the middle of 2023 and then peaked in 2024, which could account for some of the record warmth that puzzled climate scientists.

What was particularly interesting about the month of May is that land surface temperatures dropped quite a bit compared to the months prior. However, it was still the second warmest on record, after 2024.

Hausfather said the sharp drop could have been some "internal variability" that had kept the land surface temperatures elevated and that perhaps last month was a result of the end of that variability.

An important thing to also keep in mind when it comes to what we can expect in terms of 2025 making the record books, winter is when we see the greatest temperature anomalies, Hausfather said. So that could push 2025 even higher than what we're seeing now. 

On the road to warming trend of 1.5 C

Ocean temperatures have decreased in part due the end of El Niño, but remain near record highs. In May, the average ocean temperatures were 0.99 C above the 1850-1900 average, according to Berkeley Earth.

"At the moment, we are seeing, or we have just seen, a significant ocean heat wave in the North Atlantic," said Carlo Buontempo, director of Copernicus Climate Change Service (C3S).

"[Ocean temperatures are] cooler than last year and the previous one, but it's warmer than any other years we have in the record. So this is one of these things where it depends [whether] we like to see the glass half full or half empty. It's still a very warm ocean."

Though Earth did hit a 12-month average of 1.5 C, that doesn't necessarily mean failure on the Paris Agreement goal of keeping global warming below a threshold of 1.5 C. That would have to happen over a longer period, though there is no set timeframe set out in the agreement. Climate is looked at over long periods, typically spanning 20 or 30 years.

Carbon budget running out

However, a study published on Wednesday in the journal Earth System Science Data, found that — if emissions continue at 2024 rates — we have only three years until we exhaust our carbon budget to keep warming below that 1.5 C threshold.

"Record-high greenhouse gas emissions are rapidly narrowing the chance of limiting warming to 1.5 C," Joeri Rogelj, professor of climate science and policy at the Centre for Environmental Policy, Imperial College London and co-author of the report, said in a statement.

"The window to stay within 1.5°C is rapidly closing. Global warming is already affecting the lives of billions of people around the world."

Though the that threshold may be breached, climate scientists like to stress that every tenth of a degree matters.

But to keep warming below 2 C — the threshold initially set by the Paris Agreement — there needs to be a concerted effort to drastically cut CO2 emissions, as Antonio Gutteres, secretary-general of the United Nations, has continually stressed.

Buontempo said that he's hopeful that the tools we have today will at least help us deal with dealing with the outcomes of rising temperatures.

"I'm an optimist. I've always been an optimist, and my feeling is that, you know, there are plenty of positives in this terrible situation, including the fact that we never had so much information about our planet," Buontempo said. 

"We never had so much knowledge and tools to model the consequences of what's happening now. I mean, the decision is ours, right?"