Several natural factors that once helped keep the temperature below are down. For example, cloud cover and aerosols (tiny particles in the air) reflect the sunlight back into space, helping to cool the ground. However, changes in air pollution and weather changed clouds and aerosol levels.
In addition, the melting of ice and snow reduces the reflecting of the earth or Albedo. White ice reflects sunlight, but when it melts, darker earth or water absorbs more heat, accelerating warming. This feedback cycle makes hot regions hot and promotes the extreme temperatures observed in many parts of the world.
