Once again, we must unearth a study whose aim is to reinforce the climate cause and its urgency. It has just been published (1) in Nature, one leading scientific journal. It shows that, now that it has finally been acknowledged that the 1.5°C limit is likely to be exceeded, the most rapid and complete reduction in carbon emissions possible should be accompanied just as immediately by massive measures to capture and store CO₂ in order to lower its concentration in the atmosphere. It is also shown that simply adapting to climate change will only postpone the problem and make it worse. Here is a timely advocacy study published to coincide with COP29 in Baku next month.

By designating such a study as militant, it is meant a supposedly scientific work or an expert report whose aim is biased from the outset, since it is designed to persuade, convince or support a cause. No fewer than thirty authors, and not the least in this field, have tackled this task. It should be emphasised from the outset that this is not scientific work, but projections of scenarios into an uncertain future. By using the results of climate models and speculating on the emissions and corrective measures that could be taken in the future, it has been clearly established that the greater the exceedance, the greater the risk of unpleasant events. It would also be more difficult to reduce excessive temperatures than to prevent them from rising in the first place. These findings are far from novel or surprising. In any case, and this is the main point of the article, it would be necessary to achieve net-negative emissions as early as possible and on a very large scale, i.e. to remove CO₂ from the atmosphere much more intensively than nature does.

Yet these experts show a lack of expertise. Of course, they show margins of uncertainty and give all the information needed about the methods and data used, but that’s just a slaughterhouse job. It is their conclusions that will not convince anyone with a modicum of critical thinking.

They explain in very qualitative terms that letting the climate overheat before cooling it would have social and economic impacts. Nobody doubts this and, fortunately, it is written in the conditional tense. However, it is the dimensions that count: it would be useful to know whether we are talking about crumbs or mountains.

According to Nature’s self-indulgent and equally militant summary (2) in its editorial section, up to 400 gigatonnes of carbon should be removed from the atmosphere by the end of the century. Duly noted!

However, the advice given on how to achieve this is not at all good advice. First of all, CO₂ emissions should be stopped immediately. We keep hearing this but, given that measures to reduce the use of fossil fuels are only progressing at a rate of 0.28% per year, it could take 314 years to reach an improbable zero[1].

Next, the dimension of the 400 Gt of carbon to be removed must be addressed, a quantity which, at the current global rate of 11 Gt/year, corresponds to 36 years of emissions. The first option suggested is reforestation, but this has not been evaluated. Let’s do it for theses clerics [2] : between 2.7 and 5.3 billion hectares of new forest would have to be planted and preserved indefinitely. A small problem overlooked by careless experts: the total surface area occupied by forests in the world is already 4.05 billion hectares, or 31% of the planet’s land area.

Perhaps aware of this impossibility – neither the surface nor the conservation ad aeternam are plausible – the authors are quick to point out that solar geo-engineering measures (reducing the intensity of absorbed irradiation) would not solve the problem and would only lead to overconfidence in climate control. For the same reason, simply adapting to a warmer climate does not suit them, as they would find it unbearable to go too far beyond the sacrosanct 1.5°C limit. So, they blithely call for the development of carbon elimination technologies! But without mentioning that current experimental capacities are 11 Mt C per year, an anecdote that is 0.0028 % of the problem they themselves are raising, and without knowing anything about the consumption of resources that this would entail, or the viability of these technologies,

This is yet another case of pseudo-scientific activism designed to impress decision-makers at the next COP29. Nothing in it is wrong, or one would have to delve into the voluminous details to find out, a task that not even peer reviewers undertake. Everything is partial and carefully chosen. This is an abuse of the hegemonic position of experts in the field, made all the more scandalous by the fact that what they advocate is unworkable. Experts like these, playing the little soldier, deserve to be sacked without pay.

1.        Schleussner C, Ganti G, Lejeune Q, Zhu B. Overconfidence in climate overshoot.
Nature [Internet]. 2024;634(August). Available from: http://dx.doi.org/10.1038/s41586-024-08020-9

2.        Carbon dioxide removal will achieve too little, too late.
Nature [Internet]. 2024;634(October):2024.
Available from: https://www.nature.com/articles/d41586-024-03266-9

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[1]     Blog post “Energy in 2023, modest trends confirmed“, https://blog.mr-int.ch/?p=11519&lang=en#

[2]     One of the most productive forest species is the eucalyptus, which can produce 15 to 30 tonnes of wood per year and hectare, and contains around 50% carbon. It reaches maturity in 15 years, which means that the forest thus formed would then remain in carbon balance. Therefore, between 75 and 150 tonnes of carbon would be retained on each hectare. To capture 400 Gt C, we would therefore need to mobilise between 2.7 and 5.3 billion hectares.

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