Changes in the sun's energy output would cause the climate to change, since the sun is the fundamental source of energy that drives our climate system.

Human activities such as deforestation, respiration, land use changes and burning of fossil fuels are changing the greenhouse effect of the climate. The greenhouse effect is a warming that results when the atmosphere traps heat radiating from Earth toward space. Certain gases in the atmosphere block heat from escaping. Long-lived gases that remain semi-permanently in the atmosphere and do not respond physically or chemically to changes in temperature are described as "forcing" climate change. Gases, such as water vapor, which respond physically or chemically to changes in temperature are seen as "feedbacks."

Methan is a hydrocarbon gas produced through human activities such as the decomposition of wastes in landfills, agriculture, and especially rice cultivation, as well as ruminant digestion and manure management associated with domestic livestock. All these human activities are changing the natural greenhouse and the consequence of this is climate change and global warming.