[alex_h]

There's some numbers here for what it would take.

https://www.cell.com/joule/pdf/S2542-4351(19)30354-X.pdf

Basically we need 1W/m^2 of cooling for the earth, so if you could get a radiative cooling device with 100W/m^2 you'd need to cover about 1% of Earth's area

[hatsunearu]

I assume the actual radiative power is greater than the cooling capability, since cooling power = radiative power - heat intake from atmosphere - heat intake from sun

so the math works out even better than it seems...?

[davidjytang]

Let's say human inhabit roughly 10% of Earth surface. If we cover all rooftops in the world, that ought to make some effect yeah?