which of those have we actually done anything about? weve made some modest efforts on global warming but not enough to actually solve the issue, overpopulation was never really a serious issue in the first place, nuclear weapons still exist and still could be used someday, and the space stuff we have only the beginnings of an idea about how maybe deal with someday, except maybe asteroids and comets, which we have an idea of what to do but not the infrastructure to launch a big enough craft to redirect a big one in time.