What would happen to us if we suddenly switched our Sun for a red dwarf?

What would happen to us if we suddenly switched our Sun for a red dwarf?
Four exoplanets have been discovered orbiting Sun-like star tau Ceti, two of them are super-Earths residing in the Goldilocks zone
The new world, around Proxima Centauri, has a temperature suitable for liquid water to exist on its surface
The search for habitable, alien worlds needs to make room for a second “Goldilocks,” according to a Yale University researcher