Scientists want to spray chemicals into the atmosphere to try to stop global warming
- However, they admit in their report that the plan might not work, but say at least it may be possible to achieve and relatively cheap
Spraying sun-dimming chemicals high above the Earth to slow global warming could be “remarkably inexpensive”, costing about US$2.25 billion a year over a 15-year period, according to a study by US scientists.
Some researchers claim the geo-engineering technique known as stratospheric aerosol injection (SAI) could limit rising temperatures that are causing climate change.
As yet unproven and hypothetical, it would involve the use of huge hosepipes, cannons or specially designed aircraft to spray large quantities of sulphate particles into the upper layer of the atmosphere to try to create a barrier that would reflect sunlight.
Total costs to launch a hypothetical SAI effort 15 years from now would be US$3.5 billion, scientists at Harvard University said in a report published in the journal Environmental Research Letters. They said average annual operating costs would be about US$2.25 billion a year over 15 years.
The research assumes a special aircraft can be designed to fly at an altitude of about 20km and carry a load of 25 tonnes.
After input from several aerospace and engine companies, the scientists said they have developed a design that could be suitable and ready in 15 years.
They claim the plan could cut the rate of temperature change in half, but also emphasised it was completely hypothetical so might not work.
“We make no judgment about the desirability of SAI. We simply show that a hypothetical deployment programme commencing 15 years hence, while both highly uncertain and ambitious, would indeed be technically possible from an engineering perspective,” the report said.
Scientists have said SAI could result in negative consequences such as causing droughts or extreme weather, harm crop yields and potential public health and governance issues.
Commenting on the study, Phil Williamson at the University of East Anglia said: “Such scenarios are fraught with problems – and international agreement to go ahead with such action would seem near-impossible to achieve.”