NOAA's updated Annual Greenhouse Gas Index (AGGI), which measures the direct climate influence of many greenhouse gases such as carbon dioxide and methane, shows a continued steady upward trend that began with the Industrial Revolution of the 1880s.
Started in 2004, the AGGI reached 1.29 in 2010. That means the combined heating effect of long-lived greenhouse gases added to the atmosphere by human activities has increased by 29 percent since 1990, the "index" year used as a baseline for comparison. This is slightly higher than the 2009 AGGI, which was 1.27, when the combined heating effect of those additional greenhouse gases was 27 percent higher than in 1990.
"The increasing amounts of long-lived greenhouse gases in our atmosphere indicate that climate change is an issue society will be dealing with for a long time," said Jim Butler, director of the Global Monitoring Division of NOAA's Earth System Research Laboratory in Boulder, Colo. "Climate warming has the potential to affect most aspects of society, including water supplies, agriculture, ecosystems and economies. NOAA will continue to monitor these gases into the future to further understand the impacts on our planet."
The AGGI is analogous to the dial on an electric blanket -- that dial does not tell you exactly how hot you will get, nor does the AGGI predict a specific temperature. Yet just as turning the dial up increases the heat of an electric blanket, a rise in the AGGI means greater greenhouse warming.
NOAA scientists created the AGGI recognizing that carbon dioxide is not the only greenhouse gas affecting the balance of heat in the atmosphere. Many other long-lived gases also contribute to warming, although not currently as much as carbon dioxide.
The AGGI includes methane and nitrous oxide, for example, greenhouse gases that are emitted by human activities and also have natural sources and sinks. It also includes several chemicals known to deplete Earth's protective ozone layer, which are also active as greenhouse gases. The 2010 AGGI reflects several changes in the concentration of these gases, including:
Scientists at NOAA's Earth System Research Laboratory prepare the AGGI each year from atmospheric data collected through an international cooperative air sampling network of more than 100 sites around the world.
NOAA researchers developed the AGGI in 2004 and have so far back calculated it to 1978. Atmospheric composition data from ice core and other records could allow the record to be extended back centuries.
The Annual Greenhouse Gas Index (AGGI) is available online at: http://www.esrl.noaa.gov/gmd/aggi/
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