The year is 2420. Humans have adapted to their new reality. Some have developed a second, clear eyelid to protect their eyes from the CO2 laden air. Because it is so hot during the day they work at night, planting the life saving trees. Many have photos from their ancestors of how life used to be, 400 years earlier. They display them prominently to remind them of a more romantic period when trees and flowers were abundent and clouds still shaded humans from the sun.