The global temperature record in 2023 is partly “mysterious”.

Q: How would you describe 2023?

a: “2023 has been an exceptional year. This is not only a record, it beats the previous record by a record margin itself. In recorded historical data, we have never seen anything like 2023.

We started the year with La Nina, this cold phenomenon in the Pacific Ocean, which was still around until March. Then in May we saw the development of El Niño, the warm phase of this cycle. (…) It usually mainly affects temperatures in the following year, that is, in 2024. But in 2023, temperatures seem to rise with the El Niño phenomenon, much more than we have seen in the past.

We understand the long-term trend, which is driven by greenhouse gases and human impacts. We expect this to continue until we stop emitting greenhouse gases into the atmosphere. (…) But what happened in 2023 is that and something else. This is something else that is much bigger than we expect, or what we can explain at the moment. »

Question: What are the hypotheses that explain the 2023 record?

a: “There have been emails and conversations around the world between scientists. Some are saying: + Let's look at energy imbalances in the Earth, let's look at aerosols, let's look at El Niño, or what's happening in Antarctica, or in the North Atlantic. Everyone has a lot of ideas, but the calculation is not there. (..)

Perhaps El Nino is enough (to explain the recording, editor's note). But if you look at all the previous El Niño episodes, none of them have done that. So either this is very special or the atmosphere reacts to it completely differently. Or there is something else going on. (…)

The long-term trend remains in line with what we have expected for years. But the details of what happened in 2023 are a bit vague.

So we look to future data with great interest, because perhaps it will help us understand what happened last year. But we also try to analyze the past year by compiling all the observations and models. We haven't done that yet, and I think that will happen in the next few months. »

– Q: What do we expect for 2024?

a: He added: “Understanding why 2023 happened this way is important. Does this mean that it will continue? Does this mean that the consequences will begin to accelerate? We do not know! This represents a problem. (…)

It makes us more nervous, because it's no longer just that things will predictably go wrong. There are other things that are unpredictable, and that is worrying. I think this is a cause for broader concern.

The year 2023 did not follow old patterns. If previous patterns return, and 2023 is just a blip, then 2024 will be very close to 2023. If it's not a blip, or if something systematic has changed or is being changed, we can expect 2024 to be warmer. . (…) This has implications for the weather we can expect this year, heatwaves, torrential rains, coastal flooding, and everything in between. »