Illustration of a polar bear dealing with melting ice Source: "Life Preservers for Polar Bears on Sinking Arctic Ice," www.inhabitat.com, Nov. 13, 2008
The concentration of carbon dioxide in the atmosphere of six remote Arctic sites in Alaska, Canada, Iceland, Finland, and Norway reached 400 parts per million (ppm) this spring, according to measurements from the National Oceanic and Atmospheric Administration (NOAA). This marks the first time a monthly average measurement for CO2 attained the 400 ppm mark in a remote location.
Carbon dioxide (CO2), emitted by fossil fuel combustion and other activities, is considered the most prominent greenhouse gas contributing to climate change.
Research from the NOAA and the Scripps Institution of Oceanography suggests that global average atmospheric CO2 concentration was 280 ppm immediately preceding the Industrial Revolution of the 1880s. Those agencies report that atmospheric CO2 levels are currently higher than any time during the last 800,000 years.
Measurements at six remote sites reflect background levels of CO2, influenced by long-term emissions around the world, but not directly by emissions from a nearby population center. At other local population sites in NOAA's network, upwind cities influence CO2 concentrations, which have exceeded 400 ppm in spring for several years.
"The northern sites in our monitoring network tell us what is coming soon to the globe as a whole," said Pieter Tans, an atmospheric scientist with NOAA's Earth System Research Laboratory (ESRL) in Boulder, Colorado. "We will likely see global average CO2 concentrations reach 400 ppm about 2016."
"The fact that it's 400 is significant," said Jim Butler, Global Monitoring Director at the NOAA's Earth System Research Lab. "It's just a reminder to everybody that we haven't fixed this and we're still in trouble."
"These milestones are always worth noting," said Director of Energy and Global Warming Policy Myron Ebell at the conservative Competitive Enterprise Institute. "But as carbon dioxide levels have continued to increase, global temperatures flattened out, contrary to the models used by climate scientists and the UN."
According to the NOAA, the 2000s had the highest average global temperature of any decade in history.
The NOAA also calculates the Annual Greenhouse Gas Index, which takes into account the heating effects of other greenhouse gases such as methane, nitrous oxide, and chlorofluorocarbons. When those gases are also considered, the global atmosphere reached a CO2 equivalent concentration of 400 ppm in 1985 and 450 ppm in 2003.
Duncan Geere, "Atmospheric Carbon Dioxide Levels Hit Historic Milestone," wired.co.uk, June 1, 2012
"NOAA: Carbon Dioxide Levels Reach Milestone at Arctic Sites," National Oceanic and Atmospheric Administration website, May 31, 2012
Peter Rejcek, "CO2 Hits 400 Ppm in Arctic, With Antarctic Not Lagging Too Far Behind," antarcticsun.usap.gov, June 1, 2012
"Warming Gas Levels Hit 'Troubling Milestone'," cbsnews.com, May 31, 2012
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