A renewed presidency for Donald Trump is likely to be nowhere more consequential than for climate change. The coming decades will determine whether the threat of damaging and irreversible change is averted, or not. Without active US engagement, success seems inconceivable. Even with it, it would be unlikely. But, crucially, it would be conceivable. We know what to do and we know, too, that it is affordable. What is unaffordable is not to do what we need to do. But will we? That is the question.

It is indicative of the shift in the perspective of the global policy establishment that a chapter of the IMF’s October World Economic Outlook focuses on “mitigating climate change” — that is, preventing it — via “growth-and-distribution-friendly strategies”. In brief, the IMF insists that humanity can have its cake and eat it: both higher incomes and a safe climate.

As a result of rising concentrations of greenhouse gases in the atmosphere, global average temperatures are already about 1C above pre-industrial levels. On present trends, this could reach around 1.5C in a decade and 2C half a decade later. At that point, warn climate scientists, dangerous and irreversible tipping points in the climate are likely to be passed. Most governments do at least pretend to agree. Thus, in the Paris accords of December 2015, they committed themselves to keeping temperatures below these levels, even if their promises fell short of what was needed to achieve this.