DATE RESOURCES and Measurement

1978 - Present Day

Nitrous Oxide (N2O) hemispheric and global monthly means used from the NOAA/ESRL halocarbons program. A combined data set is used from two or more measurement programs. Weighted averages of monthly mean data are combined, interpolated, and smoothed for each sampling location. Hemispheric and global means are estimated by cosine weighting by latitude. (Combined Nitrous Oxide data from the NOAA/ESRL Global Monitoring Division)

Nitrous Oxide (N2O) data for the current year (2019) is from in situ samples analyzed on a gas chromatograph located at Mauna Loa (MLO), Hawaii as part of the NOAA/ESRL halocarbons in situ program. This data should be considered preliminary and will be replaced with official averaged data at the end of this year (2019).

Credits:

Dr. James Elkins (NOAA), Dr. Ed Dlugokencky (NOAA), Dr. Bradley Hall (NOAA), Dr. Geoff Dutton (NOAA), Dr. David Nanc, Dr. Debra Mondeel (NOAA)  

2000 years ago - 1977

Law Dome ice core (DSS, DE08 and DE08-2) and firn air (DSSW20K) N2O concentrations for the past 2000 years.

Credits:

Etheridge, D.M., L.P. Steele, R.L. Langenfelds, R.J. Francey, J.-M. Barnola, and V.I. Morgan. 1996. Natural and anthropogenic changes in atmospheric CO2 over the last 1000 years from air in Antarctic ice and firn. Journal of Geophysical Research, 101, 4115-4128.

Etheridge, D.M., L.P. Steele, R.J. Francey, and R.L. Langenfelds. 1998. Atmospheric methane between 1000 A.D. and present: evidence of anthropogenic emissions and climatic variability. Journal of Geophysical Research, 103, 15979-15996.

MacFarling Meure, C., D. Etheridge, C. Trudinger, P. Steele, R. Langenfelds, T. van Ommen, A. Smith, and J. Elkins. 2006. The Law Dome CO2, CH4 and N2O Ice Core Records Extended to 2000 years BP. Geophysical Research Letters, Vol. 33, No. 14, L14810 10.1029/2006GL026152

800,000 years ago - 2000 years ago

Changes in past atmospheric nitrous oxide concentrations can be determined by measuring the composition of air trapped in ice cores from Antarctica. So far, the Antarctic Vostok and EPICA Dome C ice cores have provided a composite record of atmospheric nitrous oxide levels over the past 800,000 years.

Credits:

MIS 7.5 to 11 and MIS 17 to 19: Schilt, A., M. Baumgartner, T. Blunier, J. Schwander, R. Spahni, H. Fischer, T.F. Stocker. 2010. Glacial-Interglacial and Millennial Scale Variations in the Atmospheric Nitrous Oxide Concentration during the last 800,000 Years. Quaternary Science Reviews, 29, 182-192.

NITROUS OXIDE

A powerful greenhouse gas produced by soil cultivation practices, especially the use of commercial and organic fertilizers, fossil fuel combustion, nitric acid production, and biomass burning.