| Vol. 6 | No. 4 | Fall 2004 |
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Dialogue
The film The Day After Tomorrow created a controversy over abrupt climate change. How real is this threat? |
While many people have become accustomed to thinking of human-caused climate change occurring over the course of decades or centuries, scientific evidence shows that climate change has occurred much more quickly, in decades or even years. These abrupt climate changes have been linked to changes in the ocean circulation pattern called thermohaline circulation.
As cold, salty water sinks in the North Atlantic Ocean, warmer water is pulled north from the tropics to replace it. This circulation helps warm air temperatures over Europe. Global warming, however, could increase precipitation and melt ice caps and glaciers, releasing more fresh water into the North Atlantic. This less salty water would not be dense enough to sink and pull warm water northward, causing air temperatures in the region to drop significantly. This would not, however, cause an ice age, because any cooling would occur only in regions currently warmed by the ocean circulation, and Earth as a whole is warming.
Along with the possibility of an abrupt temperature shift, climate change makes droughts, torrential rains, heat waves, and other extreme weather events more likely. We can slow global warming and minimize the risk of these potentially disastrous events by reducing our emissions of heat-trapping gases.
For answers to other questions about abrupt climate change, visit the Global Environment section of our website.
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