Opec and the IEA are keen to stress that the headline numbers in their long term energy outlooks to 2040 are “not forecasts” and “not about making predictions.”

But the distinction is often lost even before the numbers leave the organizations themselves. The press releases and executive summaries are full of “will” and “set to” with conditional phrasing light-to-non-existent.

Opec Secretary General Mohammed Barkindo, speaking in the...