The summer’s heat waves baked the eastern United States, parts of Africa and eastern Asia, and above all Russia, which lost millions of acres of wheat and thousands of lives in a drought worse than any other in the historical record.

Seemingly disconnected, these far-flung disasters are reviving the question of whether global warming is causing more weather extremes.

The collective answer of the scientific community can be boiled down to a single word: probably.

‘The climate is changing,