Fresh from the garden an hour ago, and more snow to come. Nor are we alone. Temperatures in the northern hemisphere, and especially parts of North America have been plunging to record lows due to a shift of the polar vortex, the icy wind system that usually spends winter over the Arctic. It’s even been snowing in the Algerian Sahara – the fourth time this has happened in 42 years. My computer tells me it’s zero degrees celsius here in the UK, positively tropical compared to Chicago’s –26C with an added wind-chill factor of –53C. Stay warm, everyone.