A couple issues

All the disputed science here or there about ice caps, oil, ammo, cigarettes and all is kind of entertainingly acceptable situation setup that could be possibly explained over years of backstory or whatever. But
How can a one eyed guy get dropped into the water from hundreds of feet climb onto a rocking jet ski out of breath and hit the little girl way above him on a moving airship with a garbage pistol without sights. Also their entire goal and focus is to get the girl and stop the mariner so deacon shoots him earlier in the movie. Mariner is laying there bleeding but alive. I winged him he says and hands over the gun. Why would he not just kill him with a couple more shots. It would be nice if this were explained like they needed him alive for some reason.