geoengineering explained: the benefits and challenges of stratospheric aerosols

Stratospheric aerosols are minute particles suspended in the atmosphere designed for solar radiation management (SRM). When these particles are sufficiently large, their presence becomes noticeable as they scatter and absorb sunlight, which can reduce visibility (haze) and redden sunrises and sunsets. Aerosols interact both directly and indirectly with the Earth’s radiation budget and climate. As a direct effect, the aerosols scatter sunlight directly back into space. As an indirect effect, aerosols in the lower atmosphere can modify the size of cloud particles, changing how the clouds reflect and absorb sunlight, thereby affecting the earth’s energy budget. Aerosols can also act as sites for chemical reactions to take place. Stratospheric aerosols introduce small, reflective particles into the upper atmosphere to reflect some sunlight before it reaches the surface of the Earth. This is accomplished by releasing sulfur dioxide into the stratosphere.



  • Very potent method and could off-set all the warming from the doubling of CO2
  • Affordable and relatively easy
  • Proven effective by large, natural volcanic eruptions
  • As with all sunshade schemes, overall rainfall is reduced
  • Regional weather climates will be dramatically affected which may cause dangerous outcomes, such as famine
  • Doesn’t cool poles to pre-industrial temperatures, so polar ice sheets will continue to melt
  • Will not prevent ocean acidification
  • Sky will become whiter
  • Without efforts to reduce overall CO2 production, the planet would warm rapidly if we stopped injecting SO2 into the stratosphere

see also:

Question: What is geoengineering?

Albedo Enhancement

Space Reflectors
Stratospheric Aerosols

Ambient Air Capture
Bioenergy Capture and Sequestration
Ocean Fertilization
Enhanced Weathering
Ocean Alkalinity Enhancement

LePage, M. (2012, September 20). The pros and cons of geoengineering. Retrieved from New Scientist: