HERE'S the question to put to all those who confidently declare that the recent severe winter conditions prove that global warming is nonsense: "Next time there's a heatwave in summer or an unusually mild spell in winter, will you publicly accept that the 'warmists' were right all along? If not, why not? If a cold snap means the climate is getting colder, surely a spell of hot weather proves it is getting warmer?"
Message Posted: Jan 16, 2010 2:06:04 PM
The point, of course, is that a bout of extreme weather does not prove anything about climate change. Climate is the average weather over decades.
That said, it is perfectly reasonable to ask why, if the world is warming, have so many places in the northern hemisphere been experiencing record lows? The answer is that for the past few decades cold Arctic air has mostly stayed in the Arctic over winter, trapped by strong winds spinning around the pole. This winter the vortex has weakened and in many places cold air is spilling further south than usual.
The result has been freezing weather for places as far afield as Florida, China and the UK. However, the Arctic, Greenland, much of the Mediterranean and southern Asia have been warmer than usual. So overall the northern hemisphere winter may be no colder than in previous years, it's just that the heat is distributed differently. Indeed, the average surface temperature of the entire planet during January may yet turn out to be one of the warmest on record.