According to https://en.m.wikipedia.org/wiki/Space_sunshade the simplest plan involves a huge cluster of lightweight shades at the Earth-Sun L1 point. Supposedly it would require around twenty years of daily launches of a 100-ton-to-LEO vehicle, which used to sound like science fiction.
But soon we will (fingers crossed) have Starship, a reusable space vehicle capable of 150 tons(?) to LEO and multiple launches per day. With a claimed cost to orbit of $2 million, suddenly we’re talking only around $10 billion in launch costs and five years for a 2% solar shield, which means we can solve global warming quicker and cheaper than we can build an aircraft carrier or a new subway tunnel (let alone a high speed train from Fresno to Bakersfield).
Those are optimistic estimates, yes, but it seems odd that this solution is barely on anyone’s radar.