We really are doomed because some people like to think of ways that we could kill fewer of each other?
For the last 80 or so years the nuclear weapon has likely reduced the number of deaths in war more than anything else. Of course it's hard to prove a counterfactual. This said, the cost of outright war with nukes is so terrible that the large nations of the world have avoided going toe to toe and instead engaged in smaller proxy wars, that while terrible, have had relatively low population kill rate in relation to what occurred in world wars.