One group that has issued a strong warning is the Intergovernmental Panel on Climate Change (IPCC), which is composed of scientists from all over the world. Since 1988, the IPCC has studied the global climate including why it changes, different factors that influence those changes, how a warming climate will affect living things and the environment, and what can be done to stop it. In March 2001, the IPCC concluded that most of the warming during the past fifty years has been caused by human activities. The group also projected that by the year 2100, the earth's average surface temperature will have increased between
2.5 degrees and 10.4 degrees Fahrenheit from 1990 temperature readings.
Scientists from the Intergovernmental Panel on Climate Change (IPCC) warn of the dire consequences of global warming at a 2001 news conference.
Scientists from the Intergovernmental Panel on Climate Change (IPCC) warn of the dire consequences of global warming at a 2001 news conference.
Some occurrences such as warming ocean waters, disappearing sea ice, melting permafrost, and extreme weather are already happening—and as the climate continues to grow warmer, the IPCC warns that these phenomena will become much worse. For instance, the group projects that in the next hundred years more than 50 percent of the world's glaciers will disappear, and sea levels will rise between 3.5 to 34 inches. If that happens, the result will be erosion of coastlines, destruction of wetlands, and severe flooding. Because as much as 50 percent of the world's population lives in coastal communities, floods could force millions of people to abandon their homes.
NASA offers a more conservative prediction about ocean waters, saying that although sea levels are likely to rise, the results will be nothing like those dramatized in movies: "The Statue of Liberty won't be up to her neck in water, and we won't all be living on flotillas on an endless sea. . . . The rise will mainly be due to seawater expanding from the increased ocean temperatures and run-off from the melting of continental glaciers and a slight melting of the Greenland Ice Sheet." 39 NASA says that for the most part, ice sheets in Antarctica will probably stay in place, and may even grow because of increased precipitation over the next century. The agency adds, however, that if global warming caused unusually rapid melting of polar ice sheets, sea levels would rise dramatically.