Stratospheric Aerosol Injection
proposed geoengineering method · solar radiation management research (2026)
Stratospheric aerosol injection (SAI) is a proposed form of solar geoengineering that involves dispersing reflective particles—typically sulfur dioxide—into the middle atmosphere to scatter incoming sunlight and cool the Earth’s surface. Modeled after the cooling effects of large volcanic eruptions, SAI is being studied as a potential emergency response to slow rapid global warming while decarbonization efforts continue.
Core Concepts
The Problem
Rising global temperatures are pushing Earth systems toward irreversible tipping points, yet emissions reductions alone may not be fast enough to avoid severe climate impacts.
The Claim
Intentional injection of sulfate aerosols into the stratosphere could lower global temperatures by reflecting a fraction of sunlight, buying time for a transition to a zero‑carbon economy.
Key Evidence
- •Eruption of Mount Pinatubo in 1991 injected about 20 million tons of SO₂ into the stratosphere, causing a temporary global cooling of approximately 0.5°C over the following year.
- •Climate models consistently show that SAI could offset some of the warming from doubled CO₂, though regional effects on precipitation and ozone remain uncertain.
Practical Implication
SAI represents a high‑stakes technological gamble: it might blunt the worst near‑term climate harms, but it would not address ocean acidification and could create a dependency on continuous deployment for decades or centuries.
Nuance & Limits
The technique does not solve the root cause of climate change—greenhouse gas accumulation—and carries risks such as uneven cooling, altered monsoons, and potential for rapid warming if injections were suddenly halted (termination shock).
Source Material
Citation Density
emerging
Gaps
- ⚠ The long‑term impacts on regional climate, agriculture, and biodiversity remain largely unknown.
- ⚠ Governance frameworks for deployment, monitoring, and liability are nearly nonexistent.
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