A United Nations scientific panel says global warming could be minimized by burying carbon emissions from power plants and factories before they enter the atmosphere.
One hundred experts from 32 countries report that underground storage of carbon dioxide, the main greenhouse gas blamed for rising temperatures, could play a major role in easing global warming.
The group issued its findings in Montreal, Canada Monday as part of the U.N.'s Intergovernmental Panel on Climate Change. The document was approved by more than 200 delegates from 100 countries.
The U.N. panel had previously concluded that human activities such as fossil fuel burning have raised average global temperatures between half and one degree Celsius in recent decades and that temperatures will continue to increase by one-and-a-half to nearly six degrees by the end of this century.
The new report concludes that storing carbon dioxide below Earth's crust could reduce the amount entering the atmosphere by 20 to 40 percent by the middle of this century. The panel reports that carbon burial could cut the cost of countering climate change by 30 percent or more over the next 100 years.
The head of the U.N. Environment Program, Hans Toepfer, says the most important solutions to climate change remain energy efficiency and cleaner energy sources. But he says carbon capture and storage technologies can supplement these efforts. "We have not a silver bullet solution. We must underline the high importance of energy efficiency development, where we are really saving energy," he said. "And we have to underline the high importance of other energies, not carbon intensive energies, saving this other part of the limited resources of fossil fuel."
The intergovernmental panel says many components of carbon dioxide capture and storage technology already exist, including pipelines and gas injection into geological formations. Three projects are operating in Algeria, Canada, and the North Sea off Norway. Furthermore, the experts say underground storage capacity is likely to be large enough, although the actual size of such reservoirs is uncertain. Other possible applications, such as ocean storage, are still being researched.
The costs of gathering carbon dioxide at the source, transporting it to a burial facility, and injecting it underground are estimated to vary between $17 and almost $200 dollars a ton, depending on the source and methods used.
Mr. Toepfer says the price would be worth it if governments adopt policies making carbon pollution expensive. That's why such policies, he says, are important. "If you have no limitation of CO-2, you don't have the demand for those technologies. So you must, of course, have the demand. Otherwise, you will not have those technologies used," he said.
The new report and the existing carbon storage projects are unconvincing to environmental activists.
They worry that carbon dioxide could leak, or worse, be released in large amounts by an earthquake, worsening global warming. The expert panel says the chance of leakage is not higher than that from existing natural gas and petroleum pipelines. But Greenpeace International says there are still too many questions about environmental risks, safety, and costs for carbon burial to be deployed widely.