this may sound silly. but i use dropbox to backup my wallpapers. after at least five new machines in the last few years i've always had my papes.
i have 1300 wallpapers or around 3gb, so perhaps cloud storage isn't cost effective. but if you can i would suggest online backups so long as you have the space.
interesting wallpaper btw. gonna post a wallpaper you might like in return>>6760304
beautiful! thank you for the picture