Science

there's still about 2 chances in three that it will end up in the ocean. Now, this is not to say that it wouldn't be devastating (primarily due to earthquakes and tsunamis, but the chance of it hitting a populated area is comparatively small - about 1/20. If it did hit land, it would most likely hit in Siberia. The biggest climate effect would be the equivalent of a nuclear winter, probably followed by the resumption of an ice age. Humans would survive, but it's likely civilization will take a significant step backwards.