Dear friends,
It’s high time to take geoengineering more seriously as a potential tool to mitigate climate change. 2023 was the hottest year on record, and 2024 is likely to top that. In the United States, Hurricane Helene caused over 200 deaths, and Hurricane Milton's death toll is at least two dozen. It’s well established that the hurricanes are growing stronger as global temperatures rise.
While stratospheric aerosol injection (SAI) — which sprays particles (aerosols) in the atmosphere to provide a small amount of shade from the sun — is far from a perfect solution, we should take it seriously as a possible tool for saving lives. A few months ago, my collaborators and I had released a climate emulator, Planet Parasol, that you can play with to simulate different SAI scenarios to understand its possible impact. By using AI to model its impact and thereby advance our understanding of SAI, we’ll be better prepared to decide if this is a good step.
The key idea of SAI, which is a form of climate geoengineering, is to spray reflective particles into the stratosphere to reflect a little more, say 1%, of the sunlight that otherwise would fall on Earth back into space. This small increase in reflected sunlight would be sufficient to mitigate much of the impact of human-induced warming. For example, in 1991, Mount Pinatubo ejected almost 20 tons of aerosols (sulfur dioxide) into the atmosphere and cooled down the planet by around 0.5 degrees Celsius over the following year. We should be able to induce cooling equivalent to, say, a fraction of Mount Pinatubo, via a fair, international process that’s backed by science.
There are many criticisms of SAI, such as:
- It could have unintended climate consequences, for example, disrupting local weather patterns and creating droughts or floods.
- If it were started and then stopped suddenly, it could lead to sudden warming, known as “termination shock.”
- Depending on the aerosol used (sulfur dioxide is a leading candidate), it could contribute to pollution and/or ozone depletion.
- It might reduce urgency to decarbonize (an example of a “moral hazard”).
In addition, many people have a visceral emotional reaction, as I once did before I understood the science more deeply, against “playing god” by daring to engineer the planet.
All these downsides should be balanced against the reality that people are dying.
I’m moved by meteorologist John Morales’ emotional account of the havoc caused by Hurricane Milton. The New York Times quoted him as saying, “It claims lives. It also wrecks lives.”
Skyfire AI, a drone company led by CEO Don Mathis that my team AI Fund helped to co-build, was recently on the ground in the aftermath of Helene and Milton, deploying drones to help emergency responders survey remote areas and find survivors. Mathis reports that Skyfire was credited with saving at least 13 lives. On Monday, I also spoke about AI applied to renewable energy with AES’ CEO Andres Gluski and CPO Chris Shelton. You can view our conversation here.
While I’m glad that AI can help mitigate these disasters, it saddens me that so many lives have already been lost due to climate-influenced causes. My mind frequently returns to SAI as one of the few untapped tools in our arsenal that can help. We need to be investing in SAI research now.
I’m grateful to my collaborators on the Planet Parasol emulator (a group that includes many climate scientists) including Jeremy Irvin, Daniele Visioni, Ben Kravitz, Dakota Gruener, Chris Smith, and Duncan Watson-Parris. MIT Technology Review’s James Temple wrote about his experience playing with our emulator and also outlines fair criticisms. Much work remains to be done, and making sure our actions are based on science — a task that AI can help with (witness the recent Chemistry and Physics Nobel Prizes going to innovators in AI!) – will help us make better decisions.
If you’re interested in learning more about SAI, check out this recent panel discussion where I spoke alongside climate scientists Chris Field, David Keith, Douglas MacMartin, and Simone Tilmes about the science and possible roadmaps ahead.
Keep learning!
Andrew