These are civilization-destroying events that leave little opportunity for disaster recovery. Estimates of the NEO population suggest that, over a period of one million years, about 5 such impacts can be expected. By chance, this is the number produced in the simulation. The blast, equivalent to 3 million megatons of TNT or 60,000 H-bombs, kills 7 million instantly and makes a crater 20 miles across. Within days the skies around the globe darken from the dust injected into the atmosphere.
Sunlight is blocked.
Crops fail and, over the next year, half of the Earth's human population dies, mainly from starvation. In the 621st Millennium a mile-wide comet slams into Mongolia. Some 900 million die from starvation. About 3 million people are killed instantly. During the 11th Millennium a 1.2-mile asteroid hits the southern Atlantic Ocean 400 miles off the coast of southern Argentina.