Greenhouse gases are gases that absorb infrared radiation and trap the heat that is emitted from the sun in the atmosphere, otherwise known as the greenhouse effect. Usually, gases are supposed to allow sunlight to hit the Earth's surface and bounce off back into space as infrared radiation. Because heat is being trapped in the atmosphere, the temperature of the Earth's surface does not change. This event contributes to the global crisis of global warming. Some examples of greenhouse gases are carbon dioxide and methane. Carbon dioxide is released from burning fossil fuels and methane is found within fossil fuels such as natural gas. The Marcellus Shale in New York State is an example of emissions of the greenhouse gas methane because of the process of hydraulic fracturing. Hydraulic fracturing is used for collecting natural gas, which contain methane.