Yeah we treat our ecosystem pretty badly all those toxins we dump in the ocean and in the atmosphere, they don't disappear, the're all still out there.

Anyway if we're going to be all doom and gloom you don't need a meteorite or the earth for an extinction level event, the right pandemic would do whether man made or naturally occurring.

Not nearly as exciting as the other options though, but it would leave the earth relatively unscathed for the next species to come along.