The Greenhouse Effect is a natural phenomenon where greenhouse gasses trap heat in the atmosphere and regulate the Earth's temperature. This natural effect is responsible for maintaining a habitable climate but over the last century, human activities have greatly increased atmospheric concentrations of greenhouse gasses. According to the Intergovernmental Panel on Climate Change (IPCC), it is very likely that this increase of human-generated GHG emissions, which has accelerated since the mid of the 20th century, is the primary cause of climate change. Atmospheric concentrations of GHG emissions now far exceed the average of the past several thousand years. Significant land use changes, burning of fossil fuels, and agricultural practices have all contributed to this observed increase. Global climate models clearly show that human activity is having an effect on global temperatures.