Dear friends,
A new report from UN Climate Change says that the world might be on track for 2.5 °C of warming by the end of the century, a potentially catastrophic level of warming that’s far above the 1.5 °C target of the 2015 Paris Agreement. I think it is time to seriously consider a specific solution in which AI can play a meaningful role: Climate geoengineering via stratospheric aerosol injection.
Stratospheric aerosol injection involves spraying fine particles that reflect sunlight high in the atmosphere. By increasing the reflectivity (or albedo) of the planet, we can slow down the rate at which sunlight warms it, and thereby buy more time to reduce carbon emissions and develop mitigations. Harvard Professor David Keith explains the science behind this idea is in his book, A Case for Climate Engineering.
AI will be important in this effort because:
- The aerosols will likely be delivered via custom aircraft. Designing the specs for and autonomously piloting high-altitude drones falls well within AI capabilities.
- The details of the aerosols’ impact on the planet’s climate are still poorly understood. Average temperature should decrease, but will some regions cool faster? Will some continue to warm? How will this affect crops, rain acidity, wind currents, and myriad other factors? Machine learning will be critical for modeling the effects.
- In light of the likely impact of stratospheric aerosols on the climate as well as their potential for disparate impact, how can we decide which aerosols to use, where, and when in a way that’s equitable and improves the welfare of the planet as a whole? Optimization techniques akin to reinforcement learning could be useful.
Stratospheric aerosol injection has been criticized on the following grounds:
- Moral hazard: Doing this will reduce the incentive to reduce carbon emissions. This is true, just as requiring seat belts reduces the incentive to drive safely. Nonetheless, we’re better off with seatbelts.
- Unforeseen risks: How can we attempt something as risky as modifying the planet? What if it goes wrong? But we already have modified the planet, and it already has gone wrong. Let’s do it intentionally this time, with careful science that enables us to take baby steps that are safe.
At the current 1.1 °C of warming, the world is already experiencing increased climate-related crises. My heart goes out to the millions whose lives have been disrupted by wildfires, flooding, hurricanes, and typhoons. Just weeks ago, a forest fire came within miles of my house, and area residents were told to be ready to evacuate, a first for me. (Fortunately, the fire has since been largely contained.) It terrifies me that on the planet’s current path, the past summer’s climate — the worst I’ve experienced — might be better than what my children and I will experience for the rest of our lives.
Next week at the UN’s annual COP27 climate summit held in Egypt, government leaders will meet to discuss new agreements aimed at reducing atmospheric carbon emissions. While I hope that this meeting summons the global will to do what’s needed, I would rather count on engineers and scientists, not just politicians, to address the problem. Perhaps some of us in AI can make a critical difference.
Stay cool,
Andrew