Scientists weigh up stratospheric sunlight barrier to curb warming

Some researchers say the geo-engineering technique known as stratospheric aerosol injection (SAI) could limit rising temperatures that are causing climate change. Total costs to launch a hypothetical SAI effort 15 years from now would be $3.5 billion, scientists at Harvard University said in a report published in the journal Environmental Research Letters, adding that average annual operating costs would be about $2.25 billion a year over 15 years. The scientists emphasized that this is merely a hypothetical scenario.