The least bad would be to widely introduce regenerative farming. We could turn farms from carbon sources back into carbon sinks, reduce fertilizer and pesticide use by orders of magnitude, and grow almost the same amount of crops.<p>At the same time, this would greatly increase the ability of farmland to absorb and retain rainfall, reduce soil temperatures by up to 10 degrees, greatly offsetting the hazards to crops of climate change.
Space Powered Solar Energy at a scale where solar panels shadow 1% of the sunlight. At the same time they solve all energy problems and you will have an awesome amount of potent laser or microwave weapons to keep peace on the surface of our planet.<p>This solves so many problems at once. But who has large enough space ships to bring such a tonnage to space? (looking at you Elon...)