Five last-ditch schemes needed to prevent a global warming disaster have been outlined in a new study by the United Kingdom's Royal Society.
According to National Geographic News, United Kingdom's Royal Society's report is the first from a major scientific body devoted to ranking the various proposals for "geoengineering."
"It is an unpalatable truth that unless we can succeed in greatly reducing (greenhouse gas) emissions, we are headed for a very uncomfortable and challenging climate future," said study leader John Shepherd, an earth scientist at the University of Southampton in England, in a statement.
Should that future arrive, the society reluctantly recommends seriously considering the following five global-cooling ideas.
Volcanic eruptions can quickly cool the planet by spewing tiny droplets containing sulfur dioxide into the atmosphere, where they reflect some of the sun's rays back into space.
Researchers have proposed fighting global warming with their own "flying volcanoes"-jets or balloons that release similar droplets.
Millions of tons of these droplets would need to be sent into the air every year to cancel out current global warming, at a cost of tens of billions of US dollars, the report estimates.
Even so, the flying volcanoes would be one of the most cost-effective types of geoengineering.
Another idea is the use of computer-controlled ships that could ply the remote seas, pumping out seawater mist, which would encourage low, thick clouds to form. The clouds would reflect sunlight back into space.
It would cost more than a billion dollars to launch a fleet of a few hundred of these ships, according to the new study, a relatively small sum, as geoengineering costs go.
Scientists also propose to put huge mirrors or thin, reflective disks in orbit alongside Earth and block solar rays.
The approaches would be safe, with little in the way of side effects, according to the Royal Society.
The study also determined that since trees pull huge amounts of carbon dioxide (CO2) out of the air, planting more forests would be one of the most cost-effective ways of getting the gas out of the air.
Another proposal to prevent a global warming disaster is dissolving mountains of rock, which would speed up the natural process of rock weathering, as a way of absorbing CO2.
A big operation for artificial rock weathering would need big mines, and a lot of electricity to chemically split seawater to make an acid that would be sprayed over the rocks.