When European leaders agreed on three climate and energy targets in 2008, and established a set of policies by which to achieve them, the European Union (EU) was widely acknowledged as the world’s first major economic power to tackle the climate-change problem in earnest.

Those landmark ‘20-20-20 targets’ for 2020 aimed for a 20% reduction in greenhouse-gas emissions below 1990 levels while setting a mandatory 20% target for the share of electricity consumption coming from renewable energy sources and a 20% improvement in energy efficiency by that time.

With EU emissions now down by some 18% relative to levels in 1990, Europe is well on its way to exceeding the first and crucial goal. Against that background, the new mid-term emissions target — a 40% reduction on 1990 levels by 2030 — proposed by the European Commission last week has received a lukewarm response from environmental groups, scientists and green-minded politicians (see page 597).

The commission wants to scrap binding national renewable-energy targets and introduce a mere aspirational goal for the EU as a whole. This has led some critics to infer a Brussels-conspired counter-revolution in climate policies, which they say will deal a blow to Europe’s emerging renewable industry and open the door to a renaissance of nuclear power on the continent. But the commission’s proposal has more teeth than its critics would like to admit.

According to state-of-the-art energy-economy models, 40% emissions cuts by 2030 are achievable at reasonable cost and, provided sound investment is made in energy research, do keep Europe on track to cut emissions by at least 80% by mid-century.

Announced just as Europe is surfacing from the most severe economic downturn since the Great Depression, the cost efficiency of the plan is essential to its chances of success. To burden member countries with excessive environmental measures at this time could do more long-term harm than good. An economically weak, socially struggling region is unlikely to produce the wealth and creative power that will be needed to achieve the great transformation to a low-carbon civilization.

Europe’s latest promise on global warming could be essential to building political momentum.

That transformation is a global task. With the EU accounting for little more than 10% of global greenhouse-gas emissions, the bulk of the effort will need to be accomplished elsewhere. But although the focus of global climate policies is increasingly shifting to the world’s rising economies — and to China in particular — both the timing and the content of Europe’s latest promise on global warming could be essential to building political momentum.

With a view to the United Nations climate talks next year in Paris, where nations hope to replace the underachieving 1997 Kyoto Protocol with a more stringent global climate agreement, the EU’s bid is a clear and unambiguous signal. What Brussels has dished up well in advance of the Paris climate gala is a polite but firm invitation to the rest of the world, and one that governments from Beijing to Washington cannot lightly afford to ignore. By the end of the year, at the latest, the EU’s main economic competitors will be expected to lay on the table solid offers for that crucial round of negotiations.

In terms of the magnitude of emissions cuts, the EU’s unilateral proposal is an indication of the minimum level of commitment other developed nations can be expected to make if they take their climate-change responsibilities remotely seriously. But governments — including those of EU member states — must be reminded that gentle pathways to decarbonization such as the EU hopes to follow are by no means a guarantee of a benign future climate. In fact, even the more optimistic scenarios currently under debate would give the world at best a 50% chance of staying below 2 °C of warming, the often-cited threshold to dangerous climate change. The science strongly suggests that reducing this probability to a tolerably small value would require global emissions cuts at least twice as high as those proposed in Brussels last week.

The question of how the substantial global cuts that might be required to safely stay below 2 °C of warming should be apportioned between rich and poor countries is one that science alone cannot answer. This issue requires input from ethics and the theory of justice as much as it does from science and empirical economics. The EU’s latest climate aspirations, whether or not one considers them sufficient, are a timely reminder of the intricacies of the issues at stake.