For a global warming world, the Panel on Climate Change has predicted an increase in extreme changes of precipitation levels and global rainfall. While the scientific community is divided over many aspects of the global warming theory, the potential effect of warming on precipitation levels is not one of them. The scientific community generally accepts that, theoretically, higher temperatures would mean more evaporation, which should increase the amount of water vapor in the air. This would not necessarily mean more frequent rainfall, but the storms that do form would have more moisture to wring out. It follows that the rainfall over moist areas would increase and hurricanes would get worse because "the warmer the ocean gets, the meaner the tropical storm," reports A. E. (Sandy) MacDonald of the NOAA in Boulder, Colorado (qtd. in Begley 25). Because hurricanes are temperature-driven, and require a minimum temperature to initiate enough evaporation and condensation to produce a storm, warmer temperatures would thus increase the rate and strength of hurricane formation. Amplifying the current situation, weather satellites have recently observed an increase in ocean temperatures of twice the magnitude previously estimated (Bernard 82).
The United States' Blizzard of 1996 is an example of just what this greenhouse world would create. This storm was born when cold air blew from Canada and struck into a warm, moist air mass hovering over the Atlantic Ocean. In a warming world, this event will become more common due to the fact that "global warming has made the Atlantic an even greater source of moisture [for evaporation]," says James E. Hansen. "As the water vapor condenses," Hansen adds, "the process releases heat, so the warm moist air that feeds blizzards is more likely to be situated over the Atlantic, just waiting for a cold mass" (qtd. in Begley 27). In fact, evidence has shown that the number of intense storms over the North Atlantic and North Pacific Oceans has increased and has doubled since 1900.
Furthermore, climate model studies indicate that global warming resulting from the buildup of greenhouse gases will not be evenly distributed worldwide. This differential warming effect is forecast to "reduce the thermal gradient from equator to poles, shifting traditional patterns of winds and ocean currents" (Mintzer 141). This change in air and ocean currents is sure not only to increase the numbers and severity of storms, floods, and droughts, but also to shift weather patterns to new locales. In such a case, speculates David E. Newton, of the University of San Francisco , "productive farmlands might become deserts and arid regions might become arable" (14).
With or without climate change, the precise timing, frequency, and location of weather-related disasters are among the most difficult events to predict. However, further evidence of the forecasted enhanced hydrological cycle consistent with scientists' predictions can be seen in today's world. Heavy precipitation around the world in 1998 led to what the Red Cross has called "a year of almost unprecedented flood disasters" (qtd in Mohr and Silverthorne 9). For the United States, Thomas R. Karl, director of NOAA's National Climatic Data Center in Asheville, North Carolina reports that the frequency of extreme daily rainfall events (specifically exceeding 2 inches) has increased by about ten percent in the last century. Convincingly enough, analyses of precipitation in Russia, Japan, China, and Australia show similar trends (Karl and Knight 231).
