Global warming results primarily from human activities that cause an increase in the amount of greenhouse gases in the atmosphere, which in turn compromise the atmosphere's functional capacities, including regulating temperature and weather patterns, as stated by NASA. Global warming takes place over long periods of times, and it results from an abnormally high buildup of chemicals in the atmosphere. These gases include natural elements like carbon dioxide and oxygen, as well as synthetic compounds like volatile organic compounds, or VOCs, and chlorofluorocarbons, or CFCs.
The accumulation of these gases in the atmosphere produces a condition called the greenhouse effect. This term refers to the overall warming that the atmosphere experiences with the introduction of high volumes of gases. Warming air rising from the Earth's surface should dissipate before reaching the atmosphere. With the greenhouse effect, however, these gases rise in high volume into the atmosphere, which then traps them. The trapped gases retain heat, which in turn causes higher temperatures and helps the atmosphere hold more moisture, mostly in the form of water vapor.
The increased volume of water vapor translates to more frequent and severe precipitation, as well as a larger cloud cover. In addition to water vapor and CFCs, methane, nitrous oxide and carbon dioxide play large roles in fueling global warming. These gases and compounds derive from different sources, including fertilizer runoff, automobiles, agricultural waste and burning fossil fuels.