Scientists suggest an ingenious but still unverified way to tackle climate change: spraying chemicals by eclipse of the sun in the Earth's atmosphere.
CNN reports that research by scientists at Harvard and Yale universities, published in the Environmental Research Letters, suggests using a technique known as the introduction of stratospheric aerosols, which they say could reduce the global warming rate in half.
The technique will involve spraying large amounts of sulphate particles into the lower stratosphere of the Earth at an altitude of up to 12 miles. Scientists suggest the delivery of sulphates with specially designed high-risk aircraft, balloons or large sea pistols.
Although the technology is underdeveloped and there are no existing adaptable aircraft, researchers say "the development of a new, purpose-built tanker with significant loads will not be technologically difficult or too expensive."
They estimate the total cost of opening a hypothetical system for 15 years to about $ 3.5 billion, with ongoing costs of $ 2.25 billion a year over a period of 15 years.
The report, however, acknowledges that the technique is purely hypothetical.
"We do not make a ruling on the desirability of an SAI," the report said. "Simply show that the hypothetical deployment program, which starts from 15 years, hence both, and very uncertain and ambitious, would really be technically possible from an engineering perspective. It will also be incredibly cheap."
Researchers also recognize potential risks: co-ordination between more countries in both hemispheres would be needed, and techniques for stratospheric aerosols intrusion could endanger crop yields, lead to drought, or cause extreme weather.
The proposals also do not address the issue of increasing greenhouse gas emissions, which are the leading cause of global warming.
Despite the authors' conviction of the report, other experts were skeptical.
"From the aspect of the climate economy, solar radiation management is still a much worse solution than greenhouse gas emissions: more expensive and more risky over the long term," said Philip Talman of the Fédérale de Lausanne École Polytechnique, an expert in the climate change economics.
David Archer from the Department of Geophysical Science at the University of Chicago said: "The problem with the engineering climate in this way is that it is only a temporary band-aid that covers a problem that will remain essentially forever, in fact hundreds of thousands of years for fossil fuel CO2 to leave naturally.
"We will be tempted to continue to postpone the cleaning of our energy system, but we will leave the planet in the form of life support. If the next generation does not manage to pay the climate change bill, we will all get our warming up at once."