Scientists have come up with a new idea to save Earth from global warming. Geo-engineers from Harvard University believe that spraying "sun-dimming" into the stratosphere above the Earth could slow down global warming. They also say their would be "remarkably inexpensive," costing in the of $2.25 billion a year over a 15-year . The technique is known as stratospheric aerosol injection (SAI). It is still in its infancy and is to be proven. It would involve the use of gigantic or high-powered chemical cannons to spray chemicals into the stratosphere to act as a barrier against sunlight and harmful UV rays.
The scientists have admitted that their is currently still in the planning . They said: "We make no judgment about the of SAI. We simply show that a hypothetical deployment program commencing 15 years hence, while highly uncertain and ambitious, would indeed be technically from an engineering perspective." Not all scientists think the idea is a good . Some think it is somewhat in the sky. They say it would require a fleet of 100 specially-designed to make 4,000 missions a year, crossing most of the globe's airspace. This would require from over 100 governments. There are also concerns it could increase droughts and extreme .