Planes would not be required for stratospheric injection of SO2. It could in theory be done much more cheaply with balloons: https://caseyhandmer.wordpress.com/2023/06/06/we-should-not-let-the-earth-overheat/
Planes would not be required for stratospheric injection of SO2. It could in theory be done much more cheaply with balloons: https://caseyhandmer.wordpress.com/2023/06/06/we-should-not-let-the-earth-overheat/