A new supervolcano would be a great way to fight Global Warming. When Tambora cooked off it threw 40-50 cubic miles of material into the atmosphere. We got the Year of No Summer out of it.
Oddly enough even though volcanoes throw hundreds of millions of tons of CO2 into the atmosphere, the amount of
total CO2 drops dramatically after a supervolcano. I've seen a lot of research like that where scientists struggle to explain why pumping half a billion tons of CO2 in the atmosphere makes the total amount of CO2 drop. Said scientists just need to ask a farmer, I recall after Mt St. Helens erupted everybody was plowing the ash into their fields as fast as they could to get the ridiculous amount of nutrients it contains into the soil. You get one sickly year as the ash blocks out the sun and then every plant on earth or in the sea goes Super-Saiyan.