Will NASA actually warn us when one is discovered a day or two out, and will hit us? It seems like they keep discovering these, just before they pass by.
Or will they evacuate the government underground, and let the rest of us fend for ourselves?
An impactor a mile in diameter would destroy our civilization. Naturally the evacuation of our governing bodies to defended underground bunkers would be a necessity for the continuity of that civilization (such as it is).
Even if everyone knew where they were, the facilities are, er, would be expected to be essentially impregnable. And heavily defended.
What’s the matter, you haven’t been wondering why the gubmint has been buying trainloads of ammo?
;’)
Within a couple of hours, the entire surface of the Earth would be in complete darkness, and the clouds would persist for months to years.
The hydrologic cycle would slow to near-zero, thus all the water (which didn’t freeze at altitude) would over a matter of a week or two (for the longest rivers) run down to the oceans and there would be no rain or snow (give or take an impact on water) for months or years.
Anything unable to find water would be dead in a few days.
CO2 levels would rise (this is not even considering CO2 which might be the immediate result of the impact) due to lack of photosynthesis and fires ignited by both the flash from the impact and hot ejecta. Fires might rage for weeks, months, or in some places could at least smoulder for years.
Plant eaters would devour everything, then start to starve.
Nocturnal animals and predators would be out 24/7.
Dead plant eaters (and anything else that died) would be scavenged, repeatedly.
Every wild thing would be hungry, and so would every human when the stored food, game, and carrion ran out.
By the time the cloud cover finally went away for good, the animal and human populations would probably have dropped by over 90%. Some species would have ceased to exist.
If it’s big enough, and there are lots of them that are very big, there won’t be anywhere to hide. The survivors will envy the dead.