Pull a gazilion tons of carbon out of the atmosphere, crystallise it into gigantic diamond shards, and drop them from the stratosphere onto the 95th percentile by wealth in each country.
Why not have it drop as graphite. Could be compressed as diamonds or used as base stock for carbon fibers or carbon nanotubes or carbon future-space-filaments. More useful, more stable, and could be a more versatile export.
Per kilo, sure. But in terms of overall impact, I'll lay odds that reducing the CO2 level down to preindustrial levels would be more effective than reducing any other pollutant.