At long last the northern hemisphere is beginning to thaw out after a desperately cold spell. From Beijing to Miami, the northern continents are breathing a sigh of relief as the big freeze releases its grip, at least for the time being. As everyday life returns to near normality, oil and gas prices are easing — energy use had soared during the cold period. However, new problems could emerge this weekend in the US as a severe storm sweeps the Gulf states and threatens to disrupt oil production.
The lurch in the winter weather across these vast land masses is caused by a seesawing of pressure systems between them and the Arctic. Mild temperatures across the Arctic created far less sea ice than usual this winter. But waves of frigid Arctic air swept farther south than normal, leading to intense cold, snow and ice across temperate regions.
In spite of the current thaw, northern countries should not be lulled into a false sense of security — the pressure could easily swing back again. Severe winters in the past were often punctuated by brief milder spells, followed by more intense cold. The cold weather has not all been bad news. The deep snow has been an unexpected boost for ski resorts in Scotland, where snow has been in short supply in recent years. Even the handful of ski slopes in northern England are enjoying a vintage season.
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Those who believe the cold winter signals the end of global warming should cast an eye over the southern hemisphere. Much of Australia is enduring an intense heat wave. Bushfires have swept through large areas of southern Australia and Melbourne recorded its equal hottest night on Monday, with temperatures reaching 34C (93F).