London: Spraying highly regulated chemicals from the sun above Earth to slow global warming can be "incredibly cheap," costing about $ 3.1 billion a year over a 15-year period, according to a study by US scientists .
Some researchers say that the technique of geoengineering known as stratospheric aerosol injection (SAI) could limit the rising temperatures that are causing climate change.
Still unproven and hypothetical, it would involve the use of huge hoses, cannons or aircraft specially designed to spray large amounts of sulfate particles into the upper atmosphere to act as a reflective barrier against sunlight.
The total costs to launch a hypothetical SAI effort 15 years from now would be $ 4.8 billion, Harvard University researchers said in a report published in the journal. Environmental Research Letters, adding that annual average operating costs would be about $ 3.1 billion per year over 15 years.