a) what the sun does

or b) a potential (though IMO somewhat nutty) geoengineering project to simply reflect a bunch of sunlight back into space before it heats us up.

What you're describing sounds like maybe "resolation"? (Though also sounds like it's increasing the total amount of insolation, and thus would accelerate climate change...it's actually very similar to the soletta mirror designed to do exactly that, described in Lois Bujold's _Komarr_, part of the Vorkosigan space-opera saga.)