Energy analyst and author Michael Klare has the plot for the prequel to Avatar all written out,

It’s the torrid summer of 2144, just a decade before Avatar begins.  (That movie takes place in summer 2154, after a flight from Earth that, we’re told, involves six continuous years of sleep, which helps us backdate Jake Scully’s Venezuelan combat tours.)  As it has been for decades, the world is at war, with competing power blocs fighting bitterly over a diminishing pool of vital resources.

Three great power centers dominate the global resource struggle, all located in the northern latitudes where the climate still remains tolerable and the land still receives sufficient rainfall to support agriculture.  The first of these, in whose legions both Scully and Quaritch fight, is the North American Federation, founded after the United States, facing desertification in its southern half, invaded and absorbed Canada.  The second, Greater China, incorporating northern China, the Korean peninsula, and eastern Siberia (seized from Russia in a series of wars), dominates what’s left of Asia; the third, the North European Alliance, encompassing Germany, Russia (west of the Urals), and Scandinavia, relies heavily on Arctic resources.  As in the world portrayed by George Orwell in 1984, these powers continually jockey for dominance in shifting alliances, while their armies face one another in the torrid, still relatively resource-rich parts of the planet.  In this neo-Orwellian world, warfare and the constant pressure of resource competition are the only constants.

It only gets more depressing if you choose to read on.