Answer;
 The radiation of the sun's electromagnetic waves 
Explanation;
- The energy that drives the climate system comes from the Sun. When the Sun's energy reaches the Earth it is partially absorbed in different parts of the climate system. 
 - The absorbed energy is converted back to heat, which causes the Earth to warm up and makes it habitable.
 - Energy from the sun heats Earth's surface, warms the atmosphere, provides energy for photosynthesis, causes evaporation, drives the weather and water cycles, and powers the ocean currents.