With the evolving global warming and thawing of permafrost, an ancient deadly virus begins to spread from Siberia across Eurasia, affecting domestic animals first and mutating quickly onto the rest of the fauna. First symptoms were found in people too and with insects like bees nearing to extinction, agriculture cannot support our survival much more than dying stock can. It's clear that life does not have a future on this planet anymore.
So, how could we destroy this virus on this large scale?
I kind of liked the idea of automated self-replicating, bio-mass fueled robots, but instead of those being the ones to destroy all life on Earth by getting out of control - could those be the ones saving it by killing the virus (although with taking everything else alive into the oblivion as well?)
Let's assume some of the humanity retreats to Mars to wait out the storm and has some grand idea of re-terraforming our only home. I just need the life melodramatically swept off its feet and to figure out how the Earth could be "safe" again - from that virus at least. Those surviving people or their descendants if cleaning the Earth would take that long, would then broadcast a command to shut those robots down. Marine life might not be threatened by the virus (which, I guess, means it has to be a very specific disease if to attack only terrestrial life...), but by the grey goo - yes. Meaning the robots will wipe clean not only the surface of the Earth but ocean trenches as well.
If the virus survived millennia basically in hibernation and now there is no ice for it to hide in, and the robots devour all life it could possibly host on, plus the Earth's atmosphere is no longer breathable... could there still be ways it could survive?