Carbon dioxide (CO2) is a colorless gas with a faint, acidic odor. It is nonflammable and slightly soluble in water. Carbon dioxide is produced by the combustion of fossil fuels such as coal, oil, and natural gas. It is also released from the decomposition of organic matter and respiration. Plants use sunlight to convert carbon dioxide into carbohydrates during photosynthesis. Carbon dioxide is present in the Earth’s atmosphere at a concentration of about 0.0385% by volume. This concentration has increased since the Industrial Revolution due to emissions from factories and automobiles. The average global temperature has risen about 1°C (1.8°F) over the past century due largely to increased concentrations of greenhouse gases such as carbon dioxide in the atmosphere.
Carbon dioxide affects climate change because it absorbs infrared radiation emitted by the Earth’s surface. Greenhouse gases like carbon dioxide trap heat in the atmosphere and cause the Earth’s average temperature to rise. This process is known as the greenhouse effect. Climate change refers to long-term shifts in temperature and typical weather patterns around the world. Climate change could cause more extreme weather conditions, rising sea levels, and changes in ecosystems, among other effects.
The United States Geological Survey (USGS) monitors atmospheric concentrations of carbon dioxide at sites across North America as part of its Global Change Research Program . The Mauna Loa Observatory in Hawaii has been measuring atmospheric CO2 levels since 1958; these measurements show that concentrations have increased from about 315 parts per million (ppm) in 1958 to more than 400 ppm today .