Humans can change their environment through activities like farming, mining, and ranching. They can also be changed by their environment. Some settlers in North America adapted to the environment by developing irrigation systems rather than changing locations. In the future, human use of natural resources like coal and oil could significantly warm the planet and melt polar ice caps, flooding many coastal cities by 2040 according to some climate models. However, many people are also trying to help the environment through conservation efforts.