“Global warming will be 1.4°C above pre-industrial levels in 2023,” reports an official from the World Meteorological Organization

In 2015, the countries signatories to the Paris agreement committed to limiting the rise in temperatures. The stated objective? Do everything so that by 2100, the mercury does not exceed 1.5°C above what the planet knew in the pre-industrial era. However, the heat waves observed in 2023 all over the world, on land and in the oceans, send a worrying message.

On the occasion of the COP28 organized in Dubai, in the United Arab Emirates, the World Meteorological Organization (WMO) looked back on the significant events of this extraordinary year, expected to be the hottest on record. The director of the climate branch of this United Nations organization, Chris Hewitt, helps us see more clearly, between symbolic threshold and alarming figures.

Franceinfo: On November 17, the Earth exceeded +2°C of warming for one day. Already in July, global average temperatures were 1.5°C above their pre-industrial average level. Have we already exceeded, in 2023, the thresholds envisaged for the end of the century?

Chris Hewitt: It’s a little more complicated than that, because these were isolated days or weeks. The Paris agreement speaks of warming over decades, over a period of at least twenty years. In 2023 we have seen exceptional warming and, at the moment, we expect this year to be 1.4°C above the pre-industrial baseline. Even if we cross the threshold of +1.5°C, this would, for the moment, only concern a single year. This is not enough to say that the limit described in the Paris agreement has been crossed.

During the heat waves observed across the globe, what can be attributed to the El Ni phenomenon?noto and what can be caused by climate change?

The warming we are witnessing is the work of long-term climate change, caused by the increase in the concentration of greenhouse gases in the atmosphere, linked to human activities. But to this is added natural variability within the climate system, for example El Niño/La Niña variability, which is one of the strongest.

Depending on whether one or the other phenomenon occurs, the global temperature is influenced in one direction or the other. Over the past three years, we have experienced unusually long La Niña conditions. However, La Niña tends to cause global average temperatures to drop slightly. Now that La Niña is over, we have moved into El Niño conditions. This results in warmer waters in the equatorial Pacific, which tend to increase global temperature.

So long-term warming is meeting these warmer conditions and this superposition is one of the main reasons we’ve had a record year for heat.

What are the risks of exceeding these thresholds?

We have the impression that these thresholds correspond to a radical change in the climate system, but this is not the case. Each fraction of a degree of this global average temperature gives rise to different situations. Limiting warming to 1.5°C or 2°C is not like taking sudden actions that immediately cause big changes. On the other hand, as the earth warms, we are also increasingly likely to experience heat waves. Naturally, we’ve seen a lot of that this year. They cause droughts, floods and many changes in weather and climate.

Let’s take the example of the melting of the cryosphere, the frozen surface of the Earth: it is obvious that when you warm the atmosphere, you tend to melt glaciers and ice caps. Unfortunately, we are seeing a pretty dramatic reduction in the amount of ice on the planet and this is directly linked to this warming. Crossing the +1.5°C threshold will not cause any sudden changes, but conditions will only get worse as the planet warms.

With the World Meteorological Organization, you presented your report on the current state of the climate on the first day of COP28. Are the decision-makers gathered in Dubai for the conference taking this data into account?

This is beyond my knowledge! We presented our interim state of the climate on the first day so that policymakers have the factual data they need to make their decisions and lead their discussions. What they do with it is beyond our control.