NOAA Celebrates 50-Year Carbon Dioxide Record

November 26, 2007

Fifty years ago the U.S. Weather Bureau, predecessor of NOAA's National Weather Service, helped sponsor a young scientist from the Scripps Institution of Oceanography to begin tracking carbon dioxide in Earth's atmosphere at two of the planet's most remote and pristine sites: the South Pole and the summit of the Mauna Loa volcano in Hawaii. This week NOAA, Scripps, the World Meteorological Organization, and other organizations will celebrate the half-century anniversary of the global record of carbon dioxide in Earth's atmosphere -- often referred to as the "Keeling Curve" in honor of that young scientist, Charles David Keeling.

CO2 measurements taken at Mauna Loa
Credit: NOAA

Atmospheric carbon dioxide monthy mean mixing ratios. Data prior to May 1974 are from the Scripps Institution of Oceanography (SIO, blue), data since May 1974 are from the National Oceanic and Atmospheric Administration (NOAA, red). A long-term trend curve is fitted to the monthly mean values.

Science, business, and policy leaders will gather Nov. 28-30 in Kona, Hawaii, at an international carbon dioxide conference to examine wide-ranging issues and concerns that have arisen from the CO2 record. Among the topics are the effects of increased atmospheric carbon dioxide on land and ocean ecosystems, energy alternatives to fossil fuels, economic effects of climate change, and the role of climate change in national security.

Panorama of Mauna Loa Observatory Site.
Credit: NOAA

Carbon dioxide is the most important of the greenhouse gases produced by humans and very likely responsible for the observed rise in global average temperatures since the mid-20th century. The Mauna Loa and South Pole data were the first to show the rate of CO2 buildup in the atmosphere. In 1974, NOAA began tracking greenhouse gases worldwide and continued global observations as the planet warmed rapidly over the past few decades.

The famous graph of increasing carbon dioxide in Earth's atmosphere has taken its place alongside E=mc2, the Double Helix, and other scientific icons. The jagged saw-tooth slope, climbing upward to the right while sharply rising and falling with the seasons, is recognized around the world as the symbol of global climate change caused by the burning of fossil fuels.

"Because of the CO2 record, we now understand how we are changing the natural climate," said Dr. Richard W. Spinrad, NOAA assistant administrator of oceanic and atmospheric research. "That profound realization is influencing important decisions about energy alternatives, land use, transportation, and other behaviors that will shape the future for generations."

The CO2 data are the basis for worldwide research into the affect of greenhouse gases on climate. Many of the scientists conducting that research were recognized this fall through a Nobel Peace Prize awarded to the United Nations Intergovernmental Panel on Climate Change. Because of the Mauna Loa measurements and the research that followed, the United States and other nations are now discussing how to control the future increase of carbon dioxide emissions.

"Now that carbon emission credits are bought, sold, and traded in the marketplace, we need more than ever to objectively quantify direct emissions resulting from human activities," said Pieter Tans, a NOAA Earth System Research Laboratory scientist who first came to the United States in 1978 to assist Keeling. "Accurate data taken straight from the air can give us the subtle information we need to understand both fossil fuel emissions and the natural carbon cycle."

Today NOAA makes more than 250 measurements at the South Pole and Mauna Loa observatories and at three others in American Samoa; Barrow, Alaska; and Trinidad Head, California. At over 60 sites around the globe, NOAA's partners fill glass or metal flasks with air and ship them to ESRL in Boulder, Colo. There scientists analyze the samples for CO2 and a host of other greenhouse gases and many other pollutants and natural compounds.

Aircraft contracted by NOAA gather similar samples at higher altitudes, while space-borne sensors detect some gases remotely through the entire height of the atmosphere. NOAA is activating a network of television broadcast towers, some of the tallest structures on Earth, to measure CO2 and other gases over several hundred miles to capture the regional characteristics of the carbon cycle.

The global CO2 data are fed into an online data framework and model called CarbonTracker, launched by NOAA earlier this year. CarbonTracker distinguishes between changes in the natural carbon cycle and those occurring in human-produced fossil fuel emissions. Its results can be used to verify emissions reports and tallies from other sources.

NOAA data are available to researchers around the globe. Complex computer models developed to understand recent and future climate change depend on NOAA atmospheric data on greenhouse gases.

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