Organisms tend to over populate their environment and this overpopulation forces the offspring to compete for the limited resources necessary for survival and reproduction. Survival of the fittest causes individual organisms to evolve into better adapted organisms. Melting ice produces large amounts of energy which are used to warm the planet. As ice forms or as ice melts, much energy is taken out of or put into the system without raising the temperature. Thus, ice helps keep the planet s temperature constant.
Snow insulates the earth by helping reduce the rate at which energy can escape into space.
Shown to the right is a molecule. The evaporation of water produces large amounts of energy which are used to warm the planet. As water goes from the liquid phase to the gas phase, much energy is put into or taken out of the system without changing the temperature. Thus, vaporization of water helps keep the planet s temperature constant. This helps keep the planet more comfortable to life.