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ScienceNitrous oxide’s chemical characteristics and interactions in the atmosphere contribute to its significance as a greenhouse gas. The following sections summarize some of these fundamental characteristics and provide links to related information: Greenhouse Gas PropertiesNitrous oxide (N2O) is a clear, colorless gas, with a slightly sweet odor. Due to its long atmospheric lifetime (approximately 120 years) and heat trapping effects —about 310 times more powerful than carbon dioxide on a per molecule basis — N2O is an important greenhouse gas. Nitrous oxide has both natural and human-related sources, and is removed from the atmosphere mainly by photolysis (i.e., breakdown by sunlight) in the stratosphere. In the United States, the main human-related sources of N2O are agricultural soil management, mobile and stationary combustion of fossil fuel, adipic acid production, and nitric acid production. N2O is also produced naturally from a wide variety of biological sources in soil and water. On a global basis, it is estimated that natural sources account for over 60% of the total N2O emissions (IPCC, 2001c).
Atmospheric ConcentrationsGlobal average atmospheric concentrations of N2O have increased from about 270 parts per billion by volume (ppbv) in 1750 to 314 ppbv in 1998, which equates to a 16% increase for the period. In the last two decades, atmospheric concentrations of N2O continue to increase at a rate of 0.25% per year. There has been significant multi-year variance in the observed growth of N2O concentrations, and the reasons for these trends are not yet fully understood (IPCC, 2001b). http://www.ghgonline.org/humaninfluencebig.htm Links to Atmospheric Measurement DataThe US Global Change Research Program provides access points to atmospheric measurement data related to nitrous oxide, as well as studies of national and world nitrous oxide emissions. The Carbon Dioxide Information Analysis Center (CDIAC) also provides access points to atmospheric measurement data related to nitrous oxide. CDIAC's data holdings include records of the concentrations of carbon dioxide and other radiatively active gases in the atmosphere and the role of the terrestrial biosphere and the oceans in the life cycles of greenhouse gases. |
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