How does stratospheric aerosol injection cool the planet?

Stratospheric aerosol injection is a proposed geoengineering technique that introduces sulfur-rich particles into the upper atmosphere to reflect sunlight and lower global temperatures. Modelled after the natural cooling effect of volcanic eruptions, it creates global dimming and increases Earth's albedo. While research suggests it could limit warming, it introduces complex political, regional, and environmental risks.

What we know

• Stratospheric aerosol injection is a solar geoengineering method designed to reduce global warming by increasing the reflection of sunlight back into space. [2, 3]
• The cooling mechanism is inspired by natural volcanic winters, utilizing sulfur-rich particles to create global dimming and increase planetary albedo. [1, 2, 4]
• The Intergovernmental Panel on Climate Change identifies it as the most-researched solar radiation modification method capable of limiting warming below 1.5 °C. [2]
• Custom aircraft have been proposed as the leading method of delivering these aerosols into the stratosphere. [2] · medium confidence

Still open

• Scientific understanding of regional climate effects, potential environmental risks, and weather system side effects remains limited.
• There is no leading candidate material agreed upon since existing stratospheric aerosols are not yet well understood.

Where to go next

• what followedWhat are the regional risks of solar radiation modification?
• how it workedHow do large volcanic eruptions create a volcanic winter?
• compared withWhat is marine cloud brightening?
• the bigger pictureWhat is solar radiation modification?
• how we knowHow did historical air pollution cause global dimming?
• an unexpected connectionHow does routine air pollution mask global warming?Pollution-driven global dimming has historically offset significant amounts of global warming, employing the same particulate reflective physics proposed for deliberate geoengineering.

Sources

• [1]stratospheric sulfate aerosols (Wikidata Q7622249) · CC0 1.0
• [2]Stratospheric aerosol injection · CC BY-SA 4.0
• [3]Solar radiation modification · CC BY-SA 4.0
• [4]Global dimming · CC BY-SA 4.0
• [5]Aerosol · CC BY-SA 4.0