Solar geoengineering is a drastic idea for cooling Earth, but it has its own set of problems with the major one being massive damage to Ozone layer; however, researchers have now identified an aerosol for solar geoengineering that may be able to cool the planet while simultaneously repairing ozone damage.
The study published in Proceedings of the National Academy of Sciences puts forward the case of deviating from the search of a non-reactive aerosol for solar geoengineering and instead looking for an aerosol that is highly reactive but in a way that would avoid ozone destruction.
Studies have shown that injecting light-reflecting sulfate aerosols into the stratosphere could be the way to cool down our Earth. However, there is a negative aspect of this. Sulfate aerosols tend to produce sulfuric acid in the stratosphere and this effective damages the ozone. Since the ozone layer absorbs ultraviolet light from the sun, ozone layer depletion can lead to increased rates skin cancer, eye damage and other adverse consequences.
If solar geoengineering is the solution to our global warming problems, then there is a need to engineer aerosol particles that effectively neutralize sulfuric, nitric, and hydrochloric acid on their surface. Researchers from Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) first eliminated all the toxic elements from the periodic table while searching for such a particle. They also got rid of the rare metals so as to keep the costs low. The choices left with them were Alkali and Alkaline Earth Metals, which included sodium and calcium carbonate.
Researchers than carried out modeling of stratospheric chemistry and eventually came to the conclusion that calcite, which is a constituent of limestone and one of the most common compounds found in the earth’s crust, could be the material they are looking for. Scientists determined that calcite could counter ozone loss by neutralizing emissions-borne acids in the atmosphere, while also reflecting light and cooling the planet.
The researchers have already begun testing calcite in lab experiments that mimic stratospheric conditions. However, scientists are quick to caution that anything introduced into the atmosphere may have unanticipated consequences. The researchers emphasize that even if all the attendant risks could be reduced to acceptable levels, solar geoengineering is not a solution to climate change.