Scientists have a revolutionary aerosol airspace barrier billion chemicals droughts engineers good huge idea judgment pie planes possible program remarkably simply still stratosphere technique to save Earth from global warming. Geo- aerosol airspace barrier billion chemicals droughts engineers good huge idea judgment pie planes possible program remarkably simply still stratosphere technique from Harvard University believe that spraying "sun-dimming" aerosol airspace barrier billion chemicals droughts engineers good huge idea judgment pie planes possible program remarkably simply still stratosphere technique high above the Earth could slow down global warming. They say this would be " aerosol airspace barrier billion chemicals droughts engineers good huge idea judgment pie planes possible program remarkably simply still stratosphere technique inexpensive," costing about $2.25 aerosol airspace barrier billion chemicals droughts engineers good huge idea judgment pie planes possible program remarkably simply still stratosphere technique a year over 15 years. The aerosol airspace barrier billion chemicals droughts engineers good huge idea judgment pie planes possible program remarkably simply still stratosphere technique is called stratospheric aerosol airspace barrier billion chemicals droughts engineers good huge idea judgment pie planes possible program remarkably simply still stratosphere technique injection (SAI). It is still yet to be proven. It would involve using aerosol airspace barrier billion chemicals droughts engineers good huge idea judgment pie planes possible program remarkably simply still stratosphere technique hoses or high-powered cannons to spray chemicals into the aerosol airspace barrier billion chemicals droughts engineers good huge idea judgment pie planes possible program remarkably simply still stratosphere technique . This would be a reflective aerosol airspace barrier billion chemicals droughts engineers good huge idea judgment pie planes possible program remarkably simply still stratosphere technique against sunlight. The scientists admitted that their idea is aerosol airspace barrier billion chemicals droughts engineers good huge idea judgment pie planes possible program remarkably simply still stratosphere technique in the planning stages. They said: "We make no aerosol airspace barrier billion chemicals droughts engineers good huge idea judgment pie planes possible program remarkably simply still stratosphere technique about the desirability of SAI. We aerosol airspace barrier billion chemicals droughts engineers good huge idea judgment pie planes possible program remarkably simply still stratosphere technique show that a hypothetical deployment aerosol airspace barrier billion chemicals droughts engineers good huge idea judgment pie planes possible program remarkably simply still stratosphere technique , while both highly uncertain and ambitious, would indeed be technically aerosol airspace barrier billion chemicals droughts engineers good huge idea judgment pie planes possible program remarkably simply still stratosphere technique ." Not all scientists think the idea is a aerosol airspace barrier billion chemicals droughts engineers good huge idea judgment pie planes possible program remarkably simply still stratosphere technique one. Some think it is aerosol airspace barrier billion chemicals droughts engineers good huge idea judgment pie planes possible program remarkably simply still stratosphere technique in the sky. They say 100 specially-designed aerosol airspace barrier billion chemicals droughts engineers good huge idea judgment pie planes possible program remarkably simply still stratosphere technique would need to make 4,000 missions a year, crossing most of the globe's aerosol airspace barrier billion chemicals droughts engineers good huge idea judgment pie planes possible program remarkably simply still stratosphere technique . Over 100 governments would need to agree to this. There are concerns it could increase aerosol airspace barrier billion chemicals droughts engineers good huge idea judgment pie planes possible program remarkably simply still stratosphere technique and extreme weather.