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Trends in Atmospheric Methane

Overview

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The concentration of methane (CH4), the most abundant organic trace gas in the atmosphere, has increased dramatically over the last few centuries, more than doubling its concentration. Atmospheric methane levels of the past 150 years far higher than those of the previous 420,000 years, and are currently 2.5 times as high as any previous level.

Recent Changes in Atmospheric Methane Concentrations

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The concentration of methane (CH4), the most abundant organic trace gas in the atmosphere, has increased dramatically over the last few centuries, more than doubling its concentration.The increasing concentrations of methane are of special concern because of its effects on climate and atmospheric chemistry.On a per molecule basis, additional methane is much more effective as a greenhouse gas than additional CO2.

Sources of atmospheric methane information include analysis of ambient air and measurement of ice cores.  The following data sets are explored here:

1. 1841-1978: Atmospheric CH4 concentrations derived from the Law Dome DE08 ice core that were published in Ethridge et al. (1992).  Data Source: Concentrations of CH4 from the Law Dome (East Side, "DE08" Site) Ice Core(a), Commonwealth Scientific and Industrial Research Organisation, Aspendale, Victoria, Australia. September 1994. http://cdiac.esd.ornl.gov/ftp/trends/methane/lawdome.259

2. 1979-1991: Atmospheric Methane at Cape Meares, Oregon, U.S.A.: A High-Resolution Data Base for the Period 1979-1992.  This data base presents continuous automated atmospheric methane (CH4) measurements taken at the atmospheric monitoring facility in Cape Meares, Oregon, by the Oregon Graduate Institute of Science and Technology. The Cape Meares data represent some 119,000 individual atmospheric methane measurements carried out during 1979-1992. Analysis of ambient air (collected 12 to 72 times daily) was carried out by means of an automated sampling and measurement system, using the method of gas chromatography and flame ionization detection. Despite the long course of the record and the large number of individual measurements, these data may all be linked to a single absolute calibration standard. Citation: Khalil, M. A. K., R. A. Rasmussen, and F. Moraes (1993), Atmospheric Methane at Cape Meares: Analysis of a High-Resolution Data Base and Its Environmental Implications, J. Geophys. Res., 98(D8), 14,753–14,770. http://cdiac.ornl.gov/ndps/db1007.html

3. 1984-2008: Marine Boundary Layer reference, a product of the Cooperative Atmospheric Data Integration Project. While the project is coordinated and maintained by the Carbon Cycle Greenhouse Gases Group of the National Oceanic and Atmospheric Administration, Earth System Research Laboratory (NOAA ESRL), it is a cooperative effort among the many organizations and institutions making high-quality atmospheric CH4 measurements. Downloaded from ftp://ftp.cmdl.noaa.gov/ccg/ch4/GLOBALVIEW/.  I nformation: http://islscp2.sesda.com/ISLSCP2_1/data/carbon/globalview_ ch4_point/0_globalview_ch4_readme.txt. Citation: GLOBALVIEW-CH4: Cooperative Atmospheric Data Integration Project - Methane. CD-ROM, NOAA ESRL, Boulder, Colorado [Also available on Internet via anonymous FTP to ftp.cmdl.noaa.gov, Path: ccg/ch4/GLOBALVIEW], 2008.

These three datasets are consistent in showing a steady climb in atmospheric methane levels. The data from Cape Meares show higher levels of methane, on average, than would be expected from the two bounding datasets, the Law Dome ice core and the Marine Boundary layer.

"Trends in Atmospheric Methane_2.gif"

Vostok Ice Core Methane Data for 420,000 Years

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In June of 1999 the latest ice core data from the Vostok site in Antarctica were published by Petit et al in the British journal Nature. These new data extended the historical record of temperature variations and atmospheric concentrations of CO2, methane and other greenhouse trace gases (GTG) back to 420,000 years before present (BP). The ice cores were drilled to over 3,600 meters -- just over 2.2 miles deep. These new data double the length of the historical record.

In the figure below, we combine the Vostok methane data with the datasets presented above. It is clear the levels of atmospheric methane found since 1841 are far higher than those of the previous 420,000 years, and are currently 2.5 times as high as those of the past 420,000 years.

Source: Petit, J.R., et al., 2001, Vostok Ice Core Data for 420,000 Years, IGBP PAGES/World Data Center for Paleoclimatology Data Contribution Series #2001-076. NOAA/NGDC Paleoclimatology Program, Boulder CO, USA.  Original Reference: Petit J.R., Jouzel J., Raynaud D., Barkov N.I., Barnola J.M., Basile I., Bender M., Chappellaz J., Davis J., Delaygue G., Delmotte M., Kotlyakov V.M., Legrand M., Lipenkov V., Lorius C., Pépin L., Ritz C., Saltzman E., Stievenard M., 1999, Climate and Atmospheric History of the Past 420,000 years from the Vostok Ice Core, Antarctica, Nature, 399, pp.429-436. Downloaded from http://www.ncdc.noaa.gov/paleo/icecore/antarctica/vostok/v ostok_methane.html. Data were provided with dates in BP format; the original paper was written in 1999; our graph shows dates as 1999-BP date.

"Trends in Atmospheric Methane_4.gif"

References

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Barnola, J.M., Raynaud, D., Korotkevich, Y.S. & Lorius, C., 1987. Vostok ice core provides 160,000-year record of atmospheric CO2. Nature, 329, 408-414.

Barnola, J.M., Pimienta, P., Raynaud, D. & Korotkevich, Y.S., 1991. CO2 climate relationship as deduced from the Vostok ice core: a re-examination based on new measurements and on a re-evaluation of the air dating. Tellus, 43B, 83-91.

Chappellaz, J., Barnola, J.-M., Raynaud, D., Korotkevich, Y.S. & Lorius, C. 1990. Ice-core record of atmospheric methane over the past 160,000 years. Nature, 345, 127-131.

GLOBALVIEW-CH4: Cooperative Atmospheric Data Integration Project - Methane. CD-ROM, NOAA ESRL, Boulder, Colorado [Also available on Internet via anonymous FTP to ftp.cmdl.noaa.gov, Path: ccg/ch4/GLOBALVIEW], 2008.

Jouzel J., C. Lorius, J. R. Petit, C. Genthon, N. I. Barkov, V. M. Kotlyakov, and V. M. Petrov, 1987, Vostok ice core: a continuous isotope temperature record over the last climatic cycle (160,000 years), Nature, 329, 1987, 402-408.

Jouzel J., N. I. Barkov, J. M. Barnola, M. Bender, J. Chappelaz, C. Genthon, V. M. Kotlyakov, V. Lipenkov, C. Lorius, J. R. Petit, D. Raynaud, G. Raisbeck, C. Ritz, T. Sowers, M. Stievenard, F. Yiou and P. Yiou, 1993, Extending the Vostok ice-core record of paleoclimate to the penultimate glacial period, Nature, 364, 1993, 407-412.
Jouzel J., C. Waelbroeck, B. Malaizé, M. Bender, J. R. Petit, N. I. Barkov, J. M. Barnola, T. King, V. M. Kotlyakov, V. Lipenkov, C. Lorius, D. Raynaud, C. Ritz and T. Sowers, 1996, Climatic interpretation of the recently extended Vostok ice records, Clim.Dyn., 12, 513-521.

Khalil, M. A. K., R. A. Rasmussen, and F. Moraes (1993), Atmospheric Methane at Cape Meares: Analysis of a High-Resolution Data Base and Its Environmental Implications, J. Geophys. Res., 98(D8), 14,753–14,770.

Khalil, M.A.K., and R.A. Rasmussen. 1992. Atmospheric methane at Cape Meares, Oregon. Rep. 92-111. Oregon Graduate Institute, Beaverton, Oregon.

Khalil, M.A.K., and R.A. Rasmussen. 1990. Atmospheric methane: Recent global trends. Environmental Science and Technology 24:549-553.

Khalil, M.A.K., and R.A. Rasmussen. 1983. Sources, sinks, and seasonal cycles of atmospheric methane. Journal of Geophysical Research 88:5131-5144.

Legrand M., C. Lorius, N;I. Barkov, V.N. Petrov, 1988, Vostok (Antarctica) ice core: atmospheric chemistry changes over the last climatic cycle (160,000 years), Atmos. Environ. 1988, 22, 317-331.

Lorius C., J. Jouzel, C. Ritz, L. Merlivat, N. I. Barkov, Y. S. Korotkevitch, and V. M. Kotlyakov, 1985, A 150,000-year climatic record from Antarctic ice, Nature, 316, 591-596.

Petit J.R., Jouzel J., Raynaud D., Barkov N.I., Barnola J.M., Basile I., Bender M., Chappellaz J., Davis J., Delaygue G., Delmotte M., Kotlyakov V.M., Legrand M., Lipenkov V., Lorius C., Pépin L., Ritz C., Saltzman E., Stievenard M., 1999, Climate and Atmospheric History of the Past 420,000 years from the Vostok Ice Core, Antarctica, Nature, 399, pp.429-436.

Petit J.R., L. Mounier, J. Jouzel, Y. Korotkevitch, V. Kotlyakov and C. Lorius, 1990, Paleoclimatological implications of the Vostok core dust record, Nature, 343, 56-58.

Rasmussen, R.A., and M.A.K. Khalil. 1981. Atmospheric methane: Trends and seasonal cycles. Journal of Geophysical Research 86:9826-9832.

Sowers T. M. Bender, L. D. Labeyrie, J. Jouzel, D. Raynaud, D. Martinson, and Y. S. Korotkevich, 1993, 135,000 year Vostok - SPECMAP common temporal framework, Paleoceanography v.8, p. 737-766.

Wuebbles, Donald J.  and Katharine Hayhoe.  Atmospheric Methane: Trends and Impacts.  http://www.atmosresearch.com/NCGG2a %202002.pdf

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© 2009 David Stang. All rights reserved.

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Last Revised: Wednesday, January 7, 2009