>would certainly cause a mass extinction event That's a bit bigger than Chicxulub. Someone estimated the heat from the re-entry of debris at 20kw/m2 for 7+ min

>would certainly cause a mass extinction event That's a bit bigger than Chicxulub. Someone estimated the heat from the re-entry of debris at 20kw/m2 for 7+ minutes, not close up, but far away. A random study on firefighting I just skimmed said that heat flux will destroy clothing in about 20 seconds and produce 3rd degree burns in another 20 or so. So, uh...ten times 40 seconds over practically the whole world would probably not be good. The collision that produced the Moon is speculated to have left the surface of the Earth approximately as bright as the Sun for a while, so it could be worse, but there's hardly any difference for the forms of life we can relate to. Anerobic organisms deep in the crust would have an easier time of it.