One thing that I have always worried about Antartic ice melting and unleashing some ancient black death like plague for which we dont have any immunity.
It would be extremely unlikely for ancient (millions years old) organism to be better at penetrating human immune system than organisms that evolved in arms race with us.
It's like taking a DOS virus and expecting it to infect iphones :)
Depends how far back "ancient" is. But most sicknesses only infect closely related species, and homo sapiens is here for maybe 100 000 years, so I wouldn't be too worried.
On the other hand I'm very afraid what will happen when people can download, tweak, and 3d-print viruses as a hobby.
I suppose it's how the Earth ecosystem delivers the bill for our damaging behavior.
I still believe the planetary ecosystem has a way of ridding itself of annoying biomass if a tipping point is reached. Who knows what will hit us and how fast it will hit us.
Permafrost viruses, dramatic temperature changes and generally more energy in the weather system due to global warming, catastrophic ocean acidification leading to the death of trillions and trillions of plankton, robbing us of oxygen to breathe.... there's likely a trove of "problems" we will face sooner rather than later.
That is a typical christian thinking where you try to think of humans as sinners. The reality is that modern human is far more sensitive towards wildlife, nature, trees and air quality. A typical modern human is having less babies than ever too. We are not damaging the earth.
It's like taking a DOS virus and expecting it to infect iphones :)