page_title: Carbon dioxide in Earth's atmosphere
section_title: Ongoing measurements of atmospheric CO2
hierarchical_section_title: Carbon dioxide in Earth's atmosphere / Ongoing measurements of atmospheric CO2
caption_attribution_description: English: Carbon Dioxide observations from 2005 to 2014 showing the seasonal variations and the difference between northern and southern hemispheres
context_page_description: Carbon dioxide is an important trace gas in Earth's atmosphere. It is an integral part of the carbon cycle, a biogeochemical cycle in which carbon is exchanged between the Earth's oceans, soil, rocks and the biosphere. Plants and other photoautotrophs use solar energy to produce carbohydrate from atmospheric carbon dioxide and water by photosynthesis. Almost all other organisms depend on carbohydrate derived from photosynthesis as their primary source of energy and carbon compounds. CO
  2 absorbs and emits infrared radiation at wavelengths of 4.26 µm and 14.99 µm and consequently is a greenhouse gas that plays a significant role in influencing Earth's surface temperature through the greenhouse effect.
  Concentrations of CO
  2 in the atmosphere were as high as 4,000 parts per million during the Cambrian period about 500 million years ago to as low as 180 ppm during the Quaternary glaciation of the last two million years. Reconstructed temperature records for the last 420 million years indicate that atmospheric CO
  2 concentrations peaked at ~2000 ppm during the Devonian period, and again in the Triassic period. Global annual mean CO
context_section_description: The first reproducibly accurate measurements of atmospheric CO₂ were from flask sample measurements made by Dave Keeling at Caltech in the 1950s. A few years later in March 1958 the first ongoing measurements were started by Keeling at Mauna Loa. Measurements at Mauna Loa have been ongoing since then. Now measurements are made at many sites globally. Additional measurement techniques are also used as well. Many measurement sites are part of larger global networks. Global network data are often made publicly available on the conditions of proper acknowledgment according to the respective data user policies.
  There are several surface measurement (including flasks and continuous in situ) networks including NOAA/ERSL, WDCGG, and RAMCES.  The NOAA/ESRL Baseline Observatory Network, and the Scripps Institution of Oceanography Network  data are hosted at the CDIAC at ORNL. The World Data Centre for Greenhouse Gases (WDCGG), part of GAW, data are hosted by the JMA. The Reseau Atmospherique de Mesure des Composes an Effet de Serre database (RAMCES) is part of IPSL.
  From these measurements, further products are made which integrate data from the various sources. These products also address issues such as data discontinuity and sparseness. GLOBALVIEW-CO2 is one of these products.
  Ongoing ground-based total column measurements began more recently. Column measurements typically refer to an averaged column amount denoted XCO2, rather than a surface only measurement. These measurements are made by the TCCON. These data are also hosted on the CDIAC, and made publicly available according to the data use policy.
  Satellite measurements are also a recent addition to atmospheric XCO2 measurements. SCIAMACHY aboard ESA's ENVISAT made global column XCO2 measurements from 2002–2012. AIRS aboard NASA's Aqua satellite makes global XCO2 measurements and was launched shortly after ENVISAT in 2012. More recent satellites have significantly improved the data density and precision of global measurements. Newer missions have higher spectral and spatial resolutions. JAXA's GOSAT was the first dedicated GHG monitoring satellite to successfully achieve orbit in 2009. NASA's OCO-2 launched in 2014 was the second. Various other satellites missions to measure atmospheric XCO2 are planned.
caption: Carbon Dioxide observations from 2005 to 2014 showing the seasonal variations and the difference between northern and southern hemispheres
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