Climate change could bring colder winters
Global climate change could result not only in warmer summers over the long term but also colder winters, according to some climate models.
The reason is average surface temperatures of the Earth are increasing, but it isn't happening uniformly. In some places, such as Eastern Canada, temperatures have actually been dropping, climatologists say.
The colder winter scenario is based on what happens in the Gulf Stream, a major ocean current that brings warmer weather from the tropics up into the North Atlantic.
Normally, the Gulf Stream brings up dense, saline water in a process called deep water formation. When the water cools, it sinks down into the ocean floor, releasing heat at the surface. The heat warms the atmosphere, which is why northwestern Europe is warm for its latitude.
University of Toronto physics Prof. Richard Peltier said a large influx of freshwater into the North Atlantic could reduce the rate of deep water formation during the winter. There's no consensus on whether this will happen, Peltier notes.
If it happens, winters could be "significantly colder" than this year's freeze in Central and Eastern Canada, Peltier said.
- FROM MARCH 11, 2003: Great Lakes ice over in deep freeze
The cold winter is part of the large natural fluctuations we've always seen over decades, he said.