From Nasa’s Earth Observatory:News: Greenhouse Gases Cause Northern Winter Warming. Greenhouse gases are the main reason why the Northern Hemisphere is warming quicker during wintertime months than the rest of the world. New climate model results published by NASA scientists in the Journal of Geophysical Research show that greenhouse gases increase the strength of the polar winds that regulate northern hemisphere climate in winter. [NASA's Earth Observatory]
It’s remarkable that, despite the overwhelming weight of scientific opinion, people who question global warming still get a hearing in respectable circles (the latest offender is the UK’s Sunday Times, which not long ago also gave credence to the dangerous myth that the HIV virus was not the cause of Aids).