Scientist dreams up sunblock for planet
Harvard researcher proposes sulfate spray in stratosphere
A Harvard scientist says spraying a sun-blocking aerosol into the stratosphere could do wonders for the planet’s sensitive skin. The ambitious and hypothetical deployment plan crafted by Harvard researcher Gernot Wagner was published in the Journal of Environmental Research Letters on Friday. It involves spraying a sulfate-based aerosol at altitudes as high as 12 miles into the atmosphere that aims to cut the rate of temperature change in half. The sulfates, which need to be redistributed into the air each year for 15 years would be dispersed using a Stratospheric Aerosol Injection Lofter, a novel aircraft that does not yet exist. The lofter would fly on oversized wings and carry up to a 25ton load into the high-altitude areas of the stratosphere. Each mission would last about five hours and the aerosol would be sprayed into specific injection sites north and south of the equator for even distribution. The estimated cost of the launching the system in 2033 comes in at around $3.5 billion with an annual running costs of about $2.25 billion. According to the report, the program is “remarkably inexpensive.” While Wagner admits that the deployment scenario is “purely hypothetical,” he said it could come to fruition in the future as Stratospheric Aerosol Injection offers valuable options for reversing climate change. “SAI should be researched for its possible use as part of a much broader climate policy portfolio. That includes, first and foremost, cutting greenhouse-gas emissions — to zero,” said Wagner. “Solar geoengineering in general and SAI in particular could then be considered as a possible part of such a broad — and ambitious — portfolio to try to keep global temperatures and other climate changes in check,” he said. According to Wagner, the sulfates in the aerosol could pose risks to humans and the environment, “The amount of sulfates is only a small fraction of the sulfates and other pollutants society emits every day,” he said. “There are indeed plenty of potential risks and other consequences that deserve much more research before anyone should want to make any kind of decision as to whether stratospheric aerosols are at all a viable approach,” he added. Wagner said SAI wouldn’t function as a long-term solution to global warming — the report states, “We simply show that a hypothetical deployment program commencing 15 years hence, while both highly uncertain and ambitious, would indeed be technically possible from an engineering perspective.”