If you haven't noticed, winter has been especially harsh this year. Much of Northern Europe is in a deep freeze, and any passengers flying through London, Frankfurt or Paris know all too well what this winter has done to travel plans. The U.S. and Canada have been slammed with major snow storms that have left people stranded and desperate during the holiday season. And it's only December…

Some people are wondering: if the planet is getting warmer, why is it so cold? The New York Times has an interesting op-ed article about the reasons behind this trend. The author, Judah Cohen, says increased snow cover in Siberia actually has a major impact on our climate–but he believes scientists have ignored the region's role in warming and cooling earth.

Cohen says snow cover in Siberia has changed jet stream patterns, pushing more air north and south rather than just east and west. That's why Northern Europe and the U.S. have seen such extreme winter weather in recent years. What do you think? Is Cohen's theory a good explanation?