I have wondered why the whole earth is not covered in feces...Take world population, everyday every one poops, add to that every animal poops daily, where does all the daily poop go, now multiple by every day in a year, year after year, its a wonder anyone could live on earth with all the poop generated..
One hundred years ago, proto-environmentalists welcomed the motorcar because it seemed certain that growing cities would be buried in horse dung pollution from personal transportation. They had slide-rules models to prove it.