Record temperatures and devastating wildfires have swept across Europe these past weeks, while Russia’s war on Ukraine continues to be felt far beyond the battlefields. Everyone is feeling the heat, either literally or figuratively, with few exceptions.

It is often said that the European Union only grows in stature and geopolitical power during times of crises, because its constituent parts are normally unwilling to reform or dig deep into their pockets when the sun is shining.

The coronavirus pandemic was a prime example of this. Before Covid-19 brought large swathes of the global economy to a standstill, the prospect of the 27 EU members borrowing billions of euros through joint debt was totally unthinkable.

Now it is established practice. The executive branch of the bloc, the EU Commission, is currently in the process of doling out €800 billion in loans and grants to national governments, to be spent on pre-approved projects.

Borrowing such a large...