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‘Stratospheric Aerosol Injection (SAI)’:
- ‘Stratospheric Aerosol Injection (SAI)’ programme is a proposed type of climate geoengineering to cut global warming.
- So far, SAI is an unverified, hypothetical technology; if implemented in the near future, it would involve use of big cannons, hoses or special types of aircraft to spray huge quantities of sulphate particles into stratosphere – the upper layer of the atmosphere.
- These particles would serve as a reflective barrier against the sunlight to reduce the amount of heat trapped in the atmosphere. Scientists believe the technology could help solve the problem of global warming to some extent.
- The aim would be to half the temperature increase caused by heat-trapping greenhouse gases.
- Theoretically if done at scale and sustained the impact can be large.
- According to Dr. Gernot Wagner of Harvard University (author of the paper promoting this programme), given the potential benefits of halving average projected increases in radiative forcing from a particular date onward, these numbers invoke the ‘incredible economics’ of solar geoengineering.
- This method would mimic what large volcanoes do. The eruptions injected million tons of sulfur dioxide aerosols into the stratosphere dropping the Earth’s lower atmosphere temperature.
- The effect only lasted a couple of years because the sulfates eventually fell to Earth.
- Although controversial, some think that trying to mimic the impacts of a volcano eruption is a viable way to control global warming. This proposed type of climate geoengineering is called stratospheric aerosol injection (SAI).
- The 1-degree temperature drop which accompanied Mount Pinatubo’s eruption of 1991 (the second largest eruption of the 20th century) is equal to about half of the human-caused warming Earth has experienced since the Industrial Revolution began.
- But perhaps the greatest reason to be sceptical of aerosol solar sunlight management is that it’s not a silver bullet. As carbon dioxide continues to increase, the oceans are becoming increasingly acidic. According to NOAA, ocean acidification can cascade through the ocean food chain, reducing the ability of shell fish and reef-building corals to produce their skeletons. Injecting aerosols into the stratosphere simply limits sunshine, it does not tackle the underlying carbon dioxide build up. The ocean would continue to acidify.
- Reflecting sunlight would likely reduce Earth’s average temperature but could also change global circulation patterns with potentially serious consequences such as changing storm tracks and precipitation patterns.
- In other words, the atmosphere is complex. Any band-aid fix is bound to have unintended consequences and possibly cause a new set of problems.