Should we abandon the objective of limiting global warming to 1.5°C?

► “It is practically out of reach”

Francois Gemenne, teacher at Sciences Po and member of the IPCC

“We know that limiting the increase in global warming to 1.5°C compared to the pre-industrial era is now practically out of reach. Including this objective in the Paris Agreement was moreover a political rather than a scientific decision, taken above all to obtain universal ratification of this agreement. This requirement had been brought forward by the small island States.

We know that we will reach this threshold of warming around 2035. To prevent it, greenhouse gas emissions would have to stop today and we would have to capture carbon from the atmosphere. To pretend to believe that this objective is achievable is to run after a pipe dream and to expose oneself to serious disappointment. It also means risking the anger of citizens when they realize that they have been lied to. The year 2035 is almost tomorrow, and we are already 1.2°C warmer. A warming that increases by a tenth of a degree every five years.

However, I did not sign the open letter from an international group of scientists called “Scientist Rebellion”, which asked to give up this objective to create an electric shock in public opinion. Making such a request before COP27 was, in my opinion, the equivalent of sabotaging this meeting, which remains symbolically important. Moreover, the countries that are most strongly asking to abandon this 1.5°C objective are the hydrocarbon-producing States, because it suits them.

It is of course necessary to keep objectives, but they must be tenable and understandable by the greatest number. We should no longer talk about long-term temperature goals, because that’s the best way to delay ambitious climate action as much as possible. If I commit to losing ten pounds before 2030, there is a lot of risk that I will continue to eat and drink until 2029.

It would therefore be better to reach agreements with close and measurable objectives year by year so that States are accountable for their commitments, which is a principle of democracy. More than long-term temperature ambitions, it seems to me more effective to have carbon budget commitments each year. Of course, agreements will undoubtedly be more difficult to find, but the signatory countries will have to act, rather than drag things out. What they are likely to do if we continue to set long-term goals. »

► “The climate is not realpolitik”

Lola Vallejo, Director of the climate program at the Institute for Sustainable Development and International Relations (IDDRI)

“It’s hard not to feel some sympathy for the dismay of scientists who have been preaching in the desert for years and hoping that by abandoning the 1.5°C target they will create a burst of mitigation policies and adaptation. However, I fear that the people who plead for this abandonment have little control over the chain reactions that it could cause.

As we know, in terms of climate, uncertainties remain excessively high. According to the IPCC, even if it is shrinking from year to year, the probability that we will stay below 1.5°C is not yet zero.

In these circumstances, we do not really see the point of abandoning this objective, which, it must be remembered, was won with great struggle during the Paris Agreement, at the initiative of the most threatened small island countries by global warming. If today none of these vulnerable countries wishes to go back on it, it is because they know to what extent the climate is not realpolitik: it is not a question of setting objectives that we are capable of to reach, but to know what rise in temperature the planet can withstand. However, at 1.5°C, the consequences on rising sea levels, biodiversity, etc., are already gigantic.

Contrary to what we sometimes hear, the Paris Agreement has enabled some very practical advances, by making it possible to set time horizons for States and industrialists. In 2020, the International Energy Agency, for example, said that to keep 1.5°C, we had to stop all investment in fossil fuels. So, of course, that was not respected, but the objective remains that.

If we were to abandon it, the risk would be to weaken the scope of these very concrete messages, but also to let certain lobbies of the carbon economy defend much less ambitious objectives, by going towards 2 or why not 3°C… Except that between 1.5 and 2°C there are a multitude of scenarios, with gradual impacts on the environment. In the event that we abandon 1.5, it is therefore towards 1.51°C that we should move, which is not necessarily easy to understand for public opinion.

This is why it is essential to maintain the most ambitious objective possible, at the risk otherwise of releasing the pressure on the means implemented to limit global warming. It’s a bit like in road safety: the objective of zero deaths must always prevail, even if we know that zero risk does not exist. »

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