When Mount Pinatubo erupted in 1991 it pushed some 20 million tons of SO₂ into the stratosphere reducing global temperatures by ~0.5°C for two years. Make Sunsets is a startup that replicates this effort at small scale to reduce global warming. To be precise, Make Sunsets launches balloons that release SO₂ into the stratosphere, creating reflective particles that cool the Earth. Make Sunsets is cheap compared to alternative measures of combating climate change such as carbon capture. They estimate that $1 per gram of SO₂ offsets the warming from 1 ton of CO₂.
As with the eruption of Pinatubo, the effect is temporary but that is both bug and feature. The bug means we need to keep doing this so long as we need to lower the temperature but the feature is that we can study the effect without too much worry that we are going down the wrong path.
Solar geoengineering has tradeoffs, as does any action, but a recent risk study finds that the mortality benefits far exceed the harms:
the reduction in mortality from cooling—a benefit—is roughly ten times larger than the increase in mortality from air pollution and ozone loss—a harm.
I agree with Casey Handmer that we ought to think of this as a cheap insurance policy, as we develop other technologies:
We should obviously be doing solar geoengineering. We are on track to radically reduce emissions in the coming years but thermal damage will lag our course correction so most of our climate pain is still ahead of us. Why risk destabilizing the West Antarctic ice sheet or melting the arctic permafrost or wet bulbing a hundred million people to death? Solar geoengineering can incrementally and reversibly buy down the risk during this knife-edge transition to a better future. We owe future generations to take all practical steps to dodge avoidable catastrophic and lasting damage to our planet.
I like that Make Sunsets is a small startup bringing attention to this issue in a bold way. My son purchased some credits on my behalf as an Xmas present. Maybe you should buy some too!
See previous MR posts on geoengineering.
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