Aircraft (small glinting sprites orbiting near the injection latitude) release SO₂, which oxidizes into fine sulfate aerosol droplets — visualized as the pale haze layer wrapping the globe in the stratosphere. The haze scatters part of the incoming sunlight back to space before it ever reaches the surface, so the sunbeam dims and the fraction reflected away (Earth's albedo) climbs. Less absorbed sunlight means a negative radiative forcing, which a slow-relaxing surface temperature tracks toward a new, cooler equilibrium — the poles visibly whiten as the anomaly drops.
dM/dt = injectionRate − M/τ (stratospheric aerosol mass)
AOD = k₁·M (optical depth ∝ mass)
Forcing = −k₂·AOD (W/m², cooling)
C·dT/dt = Forcing − λ·(T − T₀) (temperature relaxes toward new balance)
- Injection rate — how much SO₂ the fleet disperses per year (Pinatubo 1991 emitted roughly 10 Tg in one eruption, then decayed away — a sustained SAI program must keep re-injecting).
- Injection latitude — the aerosol plume drifts poleward and settles fastest at high latitude; injecting near the equator spreads the haze over more of the globe before it falls out.
- Aerosol residence time (τ) — how long a droplet survives in the stratosphere before gravitational settling and washout remove it; larger particles and lower altitudes fall out faster.
- Temp anomaly — the resulting deviation from the pre-industrial baseline once forcing and the ocean's thermal inertia reach a new balance; note it only cancels warming, it never touches the CO₂ or ocean acidification driving it.
Real-world relevance: SAI is the most-studied solar radiation management (SRM) proposal precisely because volcanic eruptions are a natural analogue — but termination shock (a sudden stop reversing decades of masked warming in a few years) and regional rainfall shifts remain open, actively debated risks.