I am favoring thistle seed over that of Cottonwood seed as the reflectant placed in the atmosphere by airplanes in the apogee of their flightpath. Thistle because it is easy to grow and harvest and is more durable and reflective than cottonwood seed.
All we need to do is match the Pinatuba volcano eruption of 1992 with its coolest summer. Pinatuba emitted some sulfur compounds of a 30 km cube into the atmosphere, reflecting sunlight. So all I need is 30,000 meter cube of thistle seed. How much farmland is this? Given some assumptions it is 30,000 farms of 30,000 square meters all in thistle. This is 900,000,000 square meters or 900,000 square kilometers. Now what states in the USA could devote nearly a million square kilometers to growing thistles for their seeds? Now the land area of the whole of the USA is about 9 million square kilometers. So, 1/9 of the land of the USA growing thistle seed could solve Global Warming.
But I think thistle is easy to grow in poor countries such as Africa and Afghanistan, (instead of growing opium, grow thistle). And if the pay were set standard pay of say a few cents per thistle-seed-capsule would mean a large income to poor families of the world.
We would need material scientists to tell us how good of a reflectant. How durable of a reflectant. How long will they last up there. How long would it take for the world's airplanes to deliver 30 cubic kilometers of thistle seed into the atmosphere. Will they clump up there?
Archimedes Plutoniumwhole entire Universe is just one big atom where dots of the electron-dot-cloud are galaxies