Another summer, another record

The season's headline number arrived in late August: the warmest summer on record for the northern hemisphere, by a margin that surprised even the forecasters who had predicted it.

The practical effects were felt in power grids, in hospital admissions and in the price of vegetables. Cities that had invested in shade, water and cooling centres coped; those that had not learned an expensive lesson.

Meteorologists are careful to separate a single hot summer from the long-term trend. But when the same record falls three years in a row, the distinction starts to feel academic.