[bryanmgreen]

Lets say the same asteroid hit the same place in Australia today....

How many people would both directly from impact/shockwave and indirectly die (infrastructure collapse, tsunamis on beach towns, climate change, etc) from this, do we think?

[not2b]

This was bigger than the dinosaur-killer, which killed almost all land animals; only a tiny fraction survived. So almost everyone would die, all over the world. The shock wave would be extremely hot and kill pretty much anything that's outside, and the fires would be massive.

[mr_toad]

This is bigger than the KT impactor. Everyone would die. So would almost every other animal and plant on Earth. The lucky ones would die instantly, the unlucky ones in the following global firestorm. The really unlucky ones might live long enough to freeze to death.

[dmbche]

No sunlight for years, no photosynthesis - same pronostic of 95% loss of life id guess