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