The people who have fully understood the trajectory of CO₂ emissions have already experienced an "Oh shit!" moment – the expression, coined by Australian philosopher Clive Hamilton, aptly describes the moment when everything, in a sort of crystallization of terror, seems pointless and derisory in the face of inescapable global warming. And a study published on August 22 in Science has done nothing to allay the fears of the most worried.

Scientists at the Potsdam Institute for Climate Impact Research have drawn on data from the Organization for Economic Cooperation and Development (OECD) to analyze the effects of 1,500 climate policies implemented in 41 countries between 1998 and 2022. Using artificial intelligence technology, they estimated the impact they have made on CO₂ emissions.

Their conclusions are distressing. They identified just 63 effective measures that reduced emissions by 4.5% to 13% in different sectors, with most improvements occurring in the building sector (24 occurrences), followed by transport (19 occurrences), industry (16 occurrences) and electricity (10 occurrences).

Constraint and inducement

A mere 63 out of 1,500 certainly deserves an "Oh shit" reaction. However, besides extremely dark charts, the study also holds the key to improving public policy. When combined with one or more other initiatives, 70% of the measures proved effective. In 2013, when China introduced an emissions trading scheme it had little effect on industry. But in 2016, emissions fell sharply when this system was coupled with strengthened financing mechanisms for energy efficiency investments, followed by a reduction in fossil fuel subsidies.

In 2015 and 2016 in the UK, the downturn of emissions in the power sector was due to the introduction of a carbon tax in mid-2013, which imposed a minimum price on British electricity producers. The measure strengthened the European Union Emissions Trading Systems.

The authors write that "for transport, 94% of the matched breaks are associated with a policy mix," but cite one exception to the rule: Pricing on its own is effective in the industry sectors dominated by companies that make large profits and by major energy producers. On the other hand, they note that "for the building and partly also the transport sectors, which both include a large share of private consumers subject to documented behavioral factors such as myopia, we found most potential for complementarities between policy instruments."

The study shows how comprehensive and complex environmental policy is. It's not just a question of constraint, but also inducement. Charges must be tempered with subsidization. We must not only rely on the market, but also guide it. It's an approach that should be applied to each sector, as well as on a societal scale, as businesses and households are crucial players. This is a crucial finding, as the environmental cause has too often been seen in terms of nuclear silos, or by focusing on isolated reforms.

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