The United States, along with the world, could become a very different place in the 21st century due to the increasing threat of global warming. Global warming is not just a hollow threat from the government, a way of forcing regulations on industry; in fact the average temperature is already rising. Unless measures are taken to reduce or even eliminated greenhouse gases many drastic problems could occur.
Carbon dioxide is the most prominent greenhouse gas. It acts like a blanket in the earth's atmosphere allowing heat to enter but little to escape. The main producers of carbon dioxide are cars, power plants and industries that use fossil fuels (EPA, Emissions). The earth's temperatures change naturally, yet in the past 50 years a measurable amount of warming has occurred. In fact, 2002 was the second warmest year on record, according to NASA (right behind 1998, and just ahead of 2001).
Average temperatures in the U.S. could very well rise another 3 to 9 degrees by this century's end. Sea levels will rise, flooding coastal areas. Heat waves will be more frequent and more intense. Droughts and wildfires will occur more often. Disease-carrying insects will expand their range. And species will be pushed to extinction. (EPA, Impacts).
With warmer temperatures the risk of heat waves will increase. There has been nearly a 4 degree rise in the average U.S. temperature in the last 50 years (Global, Impact). In 2002 none of the lower 48 states have experienced below average temperatures. "The last three 5-year periods (1998-2002, 1997-2001, 1996-2000), have been the warmest in 108 years of national records" (NOAA, Climate). In the second half of the 1990's many places in the United States had their hottest days or even seasons.
Drought is also another consequence of temperatures rising above normal. The 1999 to 2002 drought "peak[ed] in July [of] 2002 [and] when compared to other droughts of the 20th Century, [it] was as extensive as the major droughts of the last 40 years" (NOAA, Drought).