Global warming poses awful threats to many poor parts of the world (for example, Bangladesh). For Britain and Ireland, however, a more direct threat is the possibility that the Gulf Stream might switch off or reverse — something that could happen relatively quickly (and has happened before). In which case my beloved Kerry would start to resemble Sweden. So this report is scary.

Scientists have uncovered more evidence for a dramatic weakening in the vast ocean current that gives Britain its relatively balmy climate by dragging warm water northwards from the tropics. The slowdown, which climate modellers have predicted will follow global warming, has been confirmed by the most detailed study yet of ocean flow in the Atlantic.

Most alarmingly, the data reveal that a part of the current, which is usually 60 times more powerful than the Amazon river, came to a temporary halt during November 2004…