NCPA - National Center for Policy Analysis


May 27, 2004

Contrary to media reports and the scenario presented in the upcoming movie--"The Day After Tomorrow"-- global warming will not create another ice age, say scientists. This idea of a New Ice Age is based on studies of the last interglacial period, when there were abrupt climate changes.

The prevailing theory in media articles is that as global warming speeds up the hydrological cycle, additional freshwater would flow into the North Atlantic, shutting down the ocean circulation that transports heat to Arctic regions. As a result, Europe would cool and glaciers would form.

Scientists, however, dispute the extent to which ocean circulation patterns would be affected by an increase in greenhouse gases. Climate models put forth by the 2001 Intergovernmental Panel on Climate Change show that:

  • During the last glacial event 8,200 years ago, the Laurentide Ice Sheet drained into the North Atlantic, flooding it with fresh water; however, there is no evidence that such an event slowed Atlantic circulation
  • Predicted freshwater increases will likely be less than that caused by flows from the melting Laurentide Ice Sheet in North America; current freshwater flows in the Arctic are a hundred times less.
  • If carbon dioxide levels are elevated, as would be the case in global warming, there would be no permanent snow in August, which is necessary for glaciers to form in the Northern Hemisphere.

Additionally, the climate models show increased levels of greenhouse gases over Europe would be sufficient to prevent glacier formation. At worst, the transfer of heat via ocean currents in the Labrador Sea might slow down, which would create only minor changes to Europe's climate.

Source: Andrew J. Weaver and Claude Hillaire-Marcel, "Global Warming and the Next Ice Age," Science, April 16, 2004 and "Climate Change 2001: The Scientific Basis," 2001 IPCC Working Group 1.

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