Greenhouse gases are a primary contributor to global warming.
Many scientific models predict an increase in global temperatures due to an increase in these gases in the atmosphere. Methane, water vapor, ozone, nitrogen oxide, and carbon dioxide are all greenhouse gases, with the last being the most important. Human-produced sources of Carbon dioxide include the burning of fossil fuels and deforestation. Carbon dioxide levels in the atmosphere are also affected by photosynthesis. In addition, Carbon dioxide is exchanged between the atmosphere and the ocean.