What's the science behind The Day After Tomorrow?

- February 2, 2005

The dynamic climate system here on Earth is controlled by many factors, including the concentration of greenhouse gases within the atmosphere. Recently, global temperatures have been rising. In fact, the average global temperature has increased by 0.6 °C over the past century, and this warming trend has been accelerating within the past few decades. If the gradual warming persists, scientists estimate that the global mean temperature will increase 1.4 to 5.8 °C over the next century.

Recently, scientists at Woods Hole Oceanographic Institution have been exploring the possibility of abrupt climate change instigated by global warming. As warming continues, more and more Arctic ice will melt, releasing large amounts of fresh water into the Arctic ocean. These large quantities of fresh water in the polar seas have the potential to slow, or completely disrupt the thermohaline circulation of the oceans, by eliminating the density gradient that drives this circulation. Once the ocean circulation ceases, the North Atlantic region would experience cooling due to the absence of the Gulf Stream. This process could cause a regional climatic shift within a few of decades, which is very abrupt by geologic standards. This type of abrupt climate change was recently brought into the public arena by the movie, The Day After Tomorrow . The movie greatly exaggerates the speed and impact of the climate change to create the dramatic scenes desperately needed to propel the movie to national acclaim. However, the basic premise of the movie is plausible. The magnitude of the cooling event depends on the timing of the thermohaline collapse. If this scenario occurs sooner rather than later, cooling in the Northern Atlantic region may be noticeable and detrimental. If this scenario occurs later, the cooling experienced could simple offset the warming already in progress. The Day After Tomorrow succeeded in bringing global warming to the attention of the public, if only for a few weeks.

Great links on abrupt climate change:

Thomas Rossby: The canary of Atlantic climate change.
This article was recently published in the Providence Journal by a professor of GSO.

What's After the Day After Tomorrow
Be sure to check out the link to common misconceptions about abrupt climate change.

Global Warming
This site has some good links relating to global warming including a review of Michael Crichton's new book State of Fear .