$1/ton CO2 warming offset for a year. The math on stratospheric SO2 injection vs. everything else in the EA climate portfolio.
The longtermism debate running through this sub right now is partly about whether we're counting future lives correctly. Here's a concrete version of that question.
Current best estimates for cost-effective climate interventions:
- Clean cookstoves (Gold Standard): ~$5–15/ton CO2e reduced.
- High-quality carbon offsets (avoided deforestation, Blue Carbon): ~$10–50/ton.
- Direct air capture: ~$300–1,000/ton at current scale.
- Stratospheric SO2 injection via balloon: $1/ton CO2 warming offset for one year.
The mechanism is volcanic eruptions, Mt. Pinatubo temporarily cooled Earth by ~0.5°C by injecting ~20 million tons of SO2 into the stratosphere. You're replicating that effect at a fraction of the cost using weather balloons.
The $1/ton figure comes from the Tomas Pueyo deep-dive on the mechanism and cost structure: https://unchartedterritories.tomaspueyo.com/p/so2-injection
The honest EA framing here isn't "SO2 injection instead of emissions reduction." It's: given a fixed budget and the goal of reducing near-term warming, what's the expected value per dollar? At 25x–100x lower cost than most alternatives, SO2 injection buys time on the temperature curve while renewables scale.
The objections I'd expect: termination shock (real, manageable with gradual phase-down), regional precipitation effects (real, modeled, geographically concentrated), ozone chemistry (sulfate aerosols alone don't cause ozone damage — that requires CFCs, which we've massively cut). Moral hazard, not real, alternative energy is getting too cheap to meter and will be more accessible than burning fossil fuels. Each of these is a legitimate engineering constraint, not a veto.
If you're allocating climate dollars and haven't stress-tested SO2 injection against your other bets, that seems like an oversight worth correcting. Would love pushback and counter-arguments.