vWait 'till the next nuke fired in anger goes off.
Within a half hour Earth's viable population will be zero or indistinguishably close to it.
"Indistinguishably" because nobody will be around who will want to do the counting. <smirk>
Antarctica might be a little safer. There might even be someone left down there to observe: "Gaia will out." <grin>
And in, say, 150kA, there might be two little chemical machines called bacteria which happen to collide just right and form a third chemical machine and we're off and running again. <guffaw>
And about 500kA later, somebody will do a relatively trivial calculation that reveals that if you hit a Oungleding235 nucleus with a slow fargelock it will yield a hell of a large amount of Corslagy when the Oungleding235 splits ...to the tune of
Corslagy = (mass unit) multiplied by (light speed)2
And we're off and running again. <rofl>
Terry, 230RN