Scientists who've studied the issue now almost unanimously agree that the ocean levels will likely rise at least a half a meter by 2100, and possibly more if current temperature trends and energy use continue, according to John Harte, professor of energy and resources at the University of California, Berkeley, speaking at the U.S.-China Symposium on Climate Change taking place at the school this week.
The half-meter rise in sea levels, caused by a 3 to 5 degree increase in average global temperature, will lead to the loss of a few small island nations and severe impacts for places like Hong Kong. More intense and longer heat waves will lead to larger death counts than those seen in Europe during the summer in the past few years, Harte predicted. Polar bears will likely die off as their habitat vanishes.
"By 2020, the snows of Kilimanjaro could be no more," he added.
And that's the good news, he pointed out. A broad consensus of scientists also believe the world will experience increased , reduced crop yields and a rash of major fires. More data is needed on these projections, however.
Under more dire projections, tropical diseases like malaria could spread to more developed parts of the globe as temperatures climb, he added. Mass extinction of species on par with what happened prehistorically could occur as animals fail to keep pace with climate change.
Solar power and biofuels could help curb greenhouse gases and temperature increases, but some change is likely unavoidable. Carbon dioxide doesn't leave the atmosphere quickly, and swapping out current industrial technology will take time, noted Inez Fung, a researcher at the Lawrence Berkeley National Laboratory, a lab operated by the University of California for the U.S. Department of Energy.
The ecological chain reaction is also difficult to reverse. The melting of glaciers means darker earth, which absorbs more sunlight, which in turn accelerates the melting of the glaciers. Similarly, warming leads to less rainfall in certain regions. This can lead to forest fires and more warming carbon dioxide.
Today, carbon dioxide exists in a concentration of about 380 parts per million in the atmosphere, Fung said. The Earth's atmosphere had a carbon dioxide level of 275 parts per million prior to the industrial revolution.
If carbon dioxide levels remained constant for the century, a near impossible best case scenario, the temperature will rise about 2 degrees Celsius, said Fung. If normal consumption trends continue and substantial changes aren't made with regard to fossil fuel use, the amount of carbon dioxide in the atmosphere will rise to 580 parts per million, she said. That in turn would lead to a rise in global temperatures of about 3 to 5 degrees Celsius.
Quadrupling emissions would raise temperatures in the U.S. by 6 to 10 degrees Celsius on average and create dire problems, said, director of the Lawrence Berkeley lab.
"Six to 10 degrees is the difference between the temperature today and the temperature of the deepest ice age," Chu said.
Even though solar energy is gaining momentum, and policy leaders even in China have begun to create programs to curb pollution, fossil fuels aren't going away. Several companies have already committed to building new coal plants over the next 25 years. If technology to sequester the carbon dioxide that comes out of these plants underground isn't developed, these new plants will spew 145 billion tons of carbon into the atmosphere.
That's as much as humanity put into the air through coal between 1750 and 2000, said David Hawkins of the Natural Resources Defense Council.
"We can do it if we store the carbon in geologic formations," he said. "Conventional coal plants cannot effectively capture it."
While much of the global warming debate has taken place among scientists, businesses are already looking at ways to calculate the risks of rising warming, added Gary Guzy, senior vice president at Marsh USA, which advises insurers on the future risks.
"If you are about to build a hydroelectric dam, you want to think about the long-term impact on the snow pack," Guzy said.
If the sea levels rise 6 meters, possible under some models, everything south of Ft. Meyers in Florida along with the Orlando-Daytona corridor will be underwater, Guzy added.