NEW YORK, Oct. 31 (UPI) -- No viable alternatives are available to replace fossil fuels, and environmental regulations won't be enough to reduce carbon dioxide emissions that cause global warming, researchers said Thursday. That puts pressure on scientists to find new, less toxic energy sources, they said.
A research team comprised of government, energy industry and academic representatives examined several alternative energy sources to determine if any were viable replacements for fossil fuels.
The study, funded by the U.S. Department of Energy, appears in Friday's issue of the journal Science.
Fossil fuels, such as oil, coal, and natural gas, make up 85 percent of global energy sources. The remaining 15 percent comes from hydropower, nuclear power and even firewood.
There is no current alternative to fossil fuels that would maintain world economic growth while generating fewer environmental toxins, the team found.
"We don't have those energy sources off the shelf right now, but we have some time to develop them," the report's lead author, Martin Hoffert, a professor of physics at New York University in New York City, told United Press International.
"We have about 50 years. However, 50 years is not a long time."
Carbon dioxide emissions have contributed to global warming by trapping energy in the atmosphere. This energy, which would usually be sent from Earth back into space, is blocked and has been slowly heating the planet.
Latest projections show temperatures rising over the coming century by 2.5 degrees Fahrenheit to 10.4 degrees Fahrenheit.
Population growth and industrialization have increased carbon dioxide in the atmosphere from 275 parts per million to 370 ppm over the past century, Hoffert explained. That figure is expected to surpass 550 ppm in this century.
"The point of our paper is not to say it's not impossible," he said. These alternative energy sources are "all promising and they all have very big defects."
Some of the technologies the team studied included wind power, nuclear fission and fusion, and fossil fuels from which carbon had been removed. They also considered solar power satellites, which involve collecting power in outer space via satellite and beaming it to countries lacking power, such as developing nations.
Another intriguing technology examined was geo-engineering, which would have mirrors in space deflect solar radiation to prevent Earth from getting too warm.
But many of these technologies, especially wind power, solar power and nuclear fission, were found to be more expensive than fossil fuels -- especially if being implemented on a large scale.
Another avenue, called carbon capture and sequestration, involves trapping carbon dioxide and storing it elsewhere, such as in trees, oceans or reservoirs. The team found, however, that this technology is still in its infancy and researchers are unclear if it is viable.
Susanne Mosier, a staff scientist of climate change for the Union of Concerned Scientists in Cambridge, Mass., said while she supports the paper's call for a renewed research commitment to curb global warming, the solution could be right under our noses.
"There's not any one technology that's going to solve this daunting problem," Mosier told UPI. "Any one (technology) may not do it, but a combination may and they don't discuss that. There's no silver bullet here."
Although debate continues on the best technology to replace fossil fuels and stabilize -- and perhaps even minimize -- carbon dioxide emissions, scientists applauded the paper for sounding an alarm.
"I think this is a very important research finding because it brings home very clearly the huge magnitude of the problems associated with the burning of fossil fuels," Jim Terri, professor emeritus and former director of the Global Exchange Project at the University of Michigan in Ann Arbor, told UPI.
"I don't think the public appreciates, as much as they should, the huge severity of this problem."
William Schlesinger, dean of the Nicholas School of Environment and Earth Sciences at Duke University in Durham, N.C., agreed.
"I kind of think the American public responds to things that are immediately dangerous or expensive to them," he told UPI.
"There's this theory in the U.S. there's another valley in the beyond ... with untapped resources."
Americans, Schlesinger added, don't perceive global warming as an immediate threat and the government reflects that attitude.
"There's no question not only has there been a lack of commitment to research on alternative fuels, (but) I would say there's been a complete lack of interest from the (Bush) administration on alternative fuels," he said.
(Reported by Katrina Woznicki, UPI Science News, in Washington.)