Amid continuing warnings that greenhouse gases are driving up global temperatures and raising sea levels, a handful of industries and a small army of scientists are trying to drive those gases underground, where they can't do much harm.
They're using an emerging technology called "carbon capture and sequestration" that has already produced promising results.
In Algeria, for example, gas producers are pumping carbon dioxide back into the Earth, preventing a million tons a year from venting into the air.
In Canada, CO2 piped from a coal gasification plant is being injected into an aging oil and gas field to boost production. Over its lifetime, the operation will keep 20 million tons of CO2 out of the atmosphere.
And in Maryland, scientists are determining how quickly restored marshland can soak up CO2 from the atmosphere and lock it up as organic matter.
Scientists see carbon capture and storage as part of a "portfolio" of solutions to cut emissions and avoid the worst consequences of global warming. Others include conservation, alternative fuels, nuclear and renewable energy and cleaner combustion technologies.
It may be decades before the necessary laws, technologies and infrastructure - such as pipelines and injection wells - are in place. But proponents say carbon storage will expand as a growing global market in "carbon credits" and the expectation of U.S. emissions curbs provide financial incentives.
"It's not a matter of `if.' It's a matter of `when,'" said Bill Lyons, president of climate change and technology development at AES, a global power generator and distributor based in Arlington, Va.
AES has committed $10 billion over the years to develop alternative energy technologies for its industrial customers.
Not everyone is a booster. Some environmental groups see only a limited use for carbon storage. Others see it as political cover for the coal industry.
"Our priorities are to reduce dependence on fossil fuels," said Daniel A. Lashof, of the Natural Resources Defense Council in Washington. "But to the extent we continue to use fossil fuels, we need to capture the CO2 that's produced."
Greenpeace is less accommodating.
"It's being used to greenwash the coal industry in a very despicable way," said John Coequyt, an energy policy specialist with the environmental group. "We should be focusing on energy efficiency and renewables alone to address global warming."
The Energy Department says there's enough storage capacity in the U.S. to handle 1,000 years of CO2 emissions. Meanwhile, large quantities of CO2 already vented to the atmosphere can be soaked up by plant life and stored in the soil, scientists say.
Studies suggest that changes in agricultural practices, along with restoration and replanting of degraded land can enable the soil and plant life to absorb even more.
Carbon storage "really does look like an important technology," said Jim Dooley, a senior scientist with the Joint Global Change Research Institute at the University of Maryland, College Park. It's "important in the sense of helping society reduce the costs of addressing climate change, and important in the sense of its broad-scale applicability."
A by-product of combustion, CO2 is, after water vapor, the most abundant "greenhouse" gas in the atmosphere, a family of compounds that trap solar heat.
Methane, a constituent of natural gas and a byproduct of organic decomposition, is 20 times as potent as a greenhouse gas, but less abundant than CO2.
The "greenhouse effect" is critical in keeping the Earth warm enough to be habitable. But most scientists agree that when humans freed large amounts of ancient carbon by burning fossil fuels, they produced too much of a good thing.
Worldwide emissions of CO2 have grown from insignificant levels at the start of the Industrial Revolution to more than 25 billion tons a year, scientists say.
The result has been unwanted climate change - warming global temperatures, ecological changes and rising sea levels. Continued economic expansion, especially in the developing world, will accelerate the trend.
In combating the problem, power plants equipped for carbon capture would be more costly to operate than current facilities.
But the Intergovernmental Panel on Climate Change, which produced a sobering report on global warming last week, has said that carbon storage, spurred by a system of government carbon "permitting" and financial incentives such as "carbon credit" trading, could reduce power plants' CO2 emissions by 80 percent to 90 percent.
Carbon markets are still voluntary in the U.S., which has not signed the Kyoto treaty on climate change. It sets up a system by which major polluters earn credits by cutting emissions or buy them from cleaner operators.