Transcript of Hottest January on record puzzles climate scientists | BBC News

Now, let's turn to that other headline story, because scientists from the European Union say last month was the hottest January on record. Temperatures last month, 1. 75 degrees celsius above pre-industrial levels and slightly warmer than January 2024. Scientists had initially predicted a slightly cooler start to this year. Here's our climate correspondent, Joner Fisher.

It might have felt a bit chilly here in the UK, but the world has just experienced the hottest January since records began. You can see it on this chart here, how much monthly temperatures are above pre-industrial levels. Now, the great ones here, these are all the years since 1950. Then there, here you can see the last two years, 2023 and 2024. It really has been significantly hotter, 18 of the last 19 months above that global target that we talk so much about of 1. 5 degrees. Look over here, this is It's January of this year, 0. 1 degrees above the level from last year. Why is this interesting, climate scientists? Well, in short, they were not expecting it to be this hot. That's because of a naturally occurring weather phenomena that happens in the tropical Pacific. It's to do with sea temperatures, which have an impact on weather around the world. Now, it had been expected that the end the start of what's known as El Niño, which heats the world, and the start of what's known as La Niña, which has a cooling effect, would mean that temperatures didn't rise as much this year.

But that hasn't happened in January, leaving scientists scratching their heads.

The basic reason we're having records being broken and we've had this uninterrupted decades long warming trend is because we're increasing the amount of greenhouse gasses in the atmosphere. Until we stop doing that and until we, in effect, get to net zero, we're still going to be seeing record warm temperatures coming. The specifics of exactly why 2023 and 2024 and possibly 2025 were so warm, there are other elements involved there. We're trying to pin those down. But the big reason why we're so much warmer than the 19th century is because of carbon dioxide.

Scientists are now trying to work out just why this January was Was it just natural variation? Were other factors at play? Or could we have entered a new phase of accelerated global warming?