Soar - Poster

So here's the basic plot of this project:
In the distant future a runaway greenhouse effect has rendered the surface of the Earth uninhabitable.
A branch of humanity called the "skylanders" now lives in a skyborne ecosystem above the clouds.
One day our heroine falls to Earth and is taken in by another group of subterraneous humans.
The "underlanders" has one single goal: to terraform the Earth back to its original climate.
However this will destroy the ecosystem in the sky.
Our heroine vows to escape and stop the terraforming project which will begin in a matter of days.