The one good thing about Donald Trump’s failed bid to buy Greenland is that it softens up America’s allies for what is to come. This weekend Mr Trump will join his G7 counterparts in Biarritz for what promises to be one of the most bizarre meetings in its history. Summits are supposed to make global problems easier to manage. The G7 — and others of its kind, notably the G20 — are reaching a point where they result in the opposite: a world less manageable than if the leaders had never met. Mr Trump’s lunge for Greenland was the amuse-bouche before the meal.

It had all the relevant ingredients. First it showcased Mr Trump’s transactional approach to diplomacy. A country has a piece of real estate that Mr Trump covets, so he offers to buy it. Perhaps it could work both ways. Russia has long had its eye on Alaska, for example. Second, it underlined that Mr Trump loathes alliances. By cancelling his trip to Denmark over its refusal to consider the sale, Mr Trump left a close ally in no doubt that its friendship meant nothing. Fifty Danish soldiers lost their lives fighting alongside US troops in Afghanistan. This death toll is a considerably higher ratio to population than the US.

Third, Mr Trump’s motive for buying Greenland undercuts a crucial aim of the other members of the G7: to fight global warming. The territory’s attraction is that its receding ice sheets will open its land for mineral extraction. Mr Trump does not accept that global warming is taking place, except when it offers a chance to make money. Emmanuel Macron, the French president, would have found it impossible to find a choice of words on global warming to which Mr Trump could have signed up. Little surprise then that Mr Macron announced that the G7 would no longer bother with a communiqué at all. Another day in the Trump era. Another precedent dies.