Home > Global Warming as a Possible Trigger

Greenhouse gases such as carbon dioxide are accumulating in the Earth's atmosphere and causing surface air temperatures and subsurface ocean temperatures to rise. These gradual changes, along with other human alterations of the climate system (e.g., land-use changes), are producing conditions in the Earth’s climate that are outside the range of recent historical experience. Although it is not known whether these or future changes will trigger more abrupt climate changes, past abrupt climate changes have been especially common when the climate system itself was being altered.

A question of great societal relevance is whether the North Atlantic circulation, including the Gulf Stream, will remain stable under the global warming that is expected to continue for the next few centuries. A shutdown of the circulation would not induce a new ice age, but would cause major changes both in the ocean (major circulation regimes, upwelling and sinking regions, distribution of seasonal sea ice, ecological systems, and sea level) and in the atmosphere (land-sea temperature contrast, and the intensity, frequency, and paths of storms).

Other potential impacts of a global-warming induced abrupt climate change could be associated with increased frequency of extreme events related to land-surface hydrology. Great variability in precipitation patterns, ranging from heavy rainstorms and flooding to persistent drought, might become more common. In particular, some models suggest that greenhouse warming will cause El Niño manifestations to become stronger and more frequent. It is important to note that not all models agree on the potential impacts of global warming on abrupt climate change.