Carbon and hydrogen isotopic composition of methane over the last 1000 years

New measurements of the carbon and hydrogen isotopic ratios of methane (δ13C of CH4 and δD of CH4) over the last millennium are presented from the WAIS Divide, Antarctica, ice core (WDC05A), showing significant changes that likely were the result of human influences prior to the industrial revolution (at least as early as the 16th century of the common era (CE)). The δ13C of CH4 data corroborate the record from Law Dome, Antarctica, with high fidelity. The new δD of CH4 data set covaries with the δ13C of CH4 record. Both δ13C of CH4 and δD of CH4 were relatively stable and close to the present‐day values from ∼1000 to ∼1500 CE. Both isotopic ratios decreased to minima around 1700 CE, remained low until the late 18th century, and then rose exponentially to present‐day values. Our new δD of CH4 data provide an additional independent constraint for evaluating possible CH4 source histories. We searched a broad range of source scenarios using a simple box model to identify histories consistent with the constraints of the CH4 concentration and isotope data from 990–1730 CE. Results typically show a decrease over time in the biomass‐burning source (found in 85% of acceptable scenarios) and an increase in the agricultural source (found in 77% of acceptable scenarios), indicating preindustrial human influence on atmospheric methane as proposed in previous studies.

[1]  F. Joos,et al.  Climate and human influences on global biomass burning over the past two millennia , 2008 .

[2]  M. Hughes,et al.  Proxy-based reconstructions of hemispheric and global surface temperature variations over the past two millennia , 2008, Proceedings of the National Academy of Sciences.

[3]  Thomas Raddatz,et al.  A reconstruction of global agricultural areas and land cover for the last millennium , 2008 .

[4]  G. Etiope,et al.  Reappraisal of the fossil methane budget and related emission from geologic sources , 2008 .

[5]  J. Schmitt,et al.  Changing boreal methane sources and constant biomass burning during the last termination , 2008, Nature.

[6]  S. Houweling,et al.  Early anthropogenic CH4 emissions and the variation of CH4 and 13CH4 over the last millennium , 2008 .

[7]  D. Lowe,et al.  Methane carbon isotope effects caused by atomic chlorine in the marine boundary layer: Global model results compared with Southern Hemisphere measurements , 2007 .

[8]  Andrew L. Rice,et al.  Stable isotope ratios in atmospheric CH4: Implications for seasonal sources and sinks , 2007 .

[9]  C. Brühl,et al.  Isotopic composition of H2 from CH4 oxidation in the stratosphere and the troposphere , 2006 .

[10]  S. Sudo,et al.  Hydrogen and carbon isotopic measurements of methane from agricultural combustion: Implications for isotopic signatures of global biomass burning sources , 2006 .

[11]  Paul Steele,et al.  Law Dome CO2, CH4 and N2O ice core records extended to 2000 years BP , 2006 .

[12]  D. Etheridge,et al.  Centennial evolution of the atmospheric methane budget: what do the carbon isotopes tell us? , 2006 .

[13]  T. Sowers.  Late Quaternary Atmospheric CH4 Isotope Record Suggests Marine Clathrates Are Stable , 2006, Science.

[14]  F. Keppler,et al.  Methane emissions from terrestrial plants under aerobic conditions , 2006, Nature.

[15]  D. Etheridge,et al.  Unexpected Changes to the Global Methane Budget over the Past 2000 Years , 2005, Science.

[16]  D. Zhang,et al.  The ‘Little Ice Age’ recorded by sediment chemistry in Lake Erhai, southwest China , 2005 .

[17]  J. Barnola,et al.  Records of the δ13C of atmospheric CH4 over the last 2 centuries as recorded in Antarctic snow and ice , 2005 .

[18]  A. Miyata,et al.  Concentration and carbon isotope profiles of CH4 in paddy rice canopy , 2005 .

[19]  R. Lawrence Edwards,et al.  The Holocene Asian Monsoon: Links to Solar Changes and North Atlantic Climate , 2005, Science.

[20]  K. Holmgren,et al.  Highly variable Northern Hemisphere temperatures reconstructed from low- and high-resolution proxy data , 2005, Nature.

[21]  Susan Page,et al.  A record of Late Pleistocene and Holocene carbon accumulation and climate change from an equatorial peat bog (Kalimantan, Indonesia): implications for past, present and future carbon dynamics , 2004 .

[22]  E. Atlas,et al.  Carbon and hydrogen isotopic compositions of stratospheric methane: 1. High‐precision observations from the NASA ER‐2 aircraft , 2003 .

[23]  T. Ku,et al.  Climate variability in central China over the last 1270 years revealed by high-resolution stalagmite records , 2003 .

[24]  N. Yoshida,et al.  Stable isotope and radiocarbon compositions of methane emitted from tropical rice paddies and swamps in Southern Thailand , 2002 .

[25]  Houyuan Lu,et al.  The ‘Mediaeval Warm Period’ drought recorded in Lake Huguangyan, tropical South China , 2002 .

[26]  Katharine Hayhoe,et al.  Atmospheric methane and global change , 2002 .

[27]  C. Borror.  An Introduction to Statistical Methods and Data Analysis, 5th Ed. , 2002 .

[28]  R. Conrad,et al.  Seasonal variation in pathways of CH4 production and in CH4 oxidation in rice fields determined by stable carbon isotopes and specific inhibitors , 2002 .

[29]  W. Ruddiman,et al.  The case for human causes of increased atmospheric CH4 over the last 5000 years , 2001 .

[30]  C. Brühl,et al.  Carbon 13 and D kinetic isotope effects in the reactions of CH4 with O(1 D) and OH: New laboratory measurements and their implications for the isotopic composition of stratospheric methane , 2001 .

[31]  S. Tyler,et al.  High-Precision Continuous-Flow Measurement of δ13C and δD of Atmospheric CH4 , 2001 .

[32]  Zhen Wang,et al.  A 6000-year record of changes in drought and precipitation in northeastern China based on a δ13C time series from peat cellulose , 2001 .

[33]  J. Hayes,et al.  Determination of the the H3 factor in hydrogen isotope ratio monitoring mass spectrometry. , 2001, Analytical chemistry.

[34]  J. Lelieveld,et al.  Simulation of preindustrial atmospheric methane to constrain the global source strength of natural wetlands , 2000 .

[35]  Sander Houweling,et al.  The modeling of tropospheric methane: How well can point measurements be reproduced by a global model? , 2000 .

[36]  M. Manning,et al.  The trend in atmospheric methane δ13C and implications for isotopic constraints on the global methane budget , 2000 .

[37]  D. Worthy,et al.  Evidence for a link between climate and northern wetland methane emissions , 2000 .

[38]  G. Marland,et al.  Carbon dioxide emissions from fossil‐fuel use, 1751–1950 , 1999 .

[39]  E. Dlugokencky,et al.  The isotopic composition of atmospheric methane , 1999 .

[40]  D. Etheridge,et al.  Atmospheric methane between 1000 A.D. and present: Evidence of anthropogenic emissions and climatic variability , 1998 .

[41]  P. Bergamaschi.  Seasonal variations of stable hydrogen and carbon isotope ratios in methane from a Chinese rice paddy , 1997 .

[42]  D. Etheridge,et al.  Modeling air movement and bubble trapping in firn , 1997 .

[43]  J. Chanton,et al.  Methane emission from rice: Stable isotopes, diurnal variations, and CO2 exchange , 1997 .

[44]  P. Tans.  A note on isotopic ratios and the global atmospheric methane budget , 1997 .

[45]  P. M. Lang,et al.  Atmospheric gas concentrations over the past century measured in air from firn at the South Pole , 1996, Nature.

[46]  G. Brailsford,et al.  Seasonal variations in methane flux andδl3CH4 values for rice paddies in Japan and their implications , 1994 .

[47]  D. Wilbur,et al.  Kinetic isotopic fractionation during air‐water gas transfer of O2, N2, CH4, and H2 , 1992 .

[48]  D. Raynaud,et al.  Elemental and isotopic composition of occluded O2 and N2 in polar ice , 1989 .

[49]  F. Rust.  Ruminant methane delta(13C/12C) values: relation to atmospheric methane. , 1981, Science.

[50]  Colin McEvedy,et al.  Atlas of world population history , 1979 .

[51]  G. MELVYN HOWE,et al.  Atlas of world population history , 1979, Medical History.

[52]  T. Sowers.  Atmospheric methane isotope records covering the Holocene period , 2010 .

[53]  Masson-Delmotte,et al.  The Physical Science Basis , 2007 .

[54]  S. Solomon.  The Physical Science Basis : Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change , 2007 .

[55]  P. Vanrolleghem,et al.  Carbon and hydrogen isotope fractionation by microbial methane oxidation: improved determination. , 2006, Waste management.

[56]  D. Etheridge,et al.  Law Dome CO 2 , CH 4 and N 2 O ice core records extended to 2000 years , 2006 .

[57]  J. Barnola,et al.  Records of the D 13 C of atmospheric CH 4 over the last 2 centuries as recorded in Antarctic snow and ice , 2005 .

[58]  M. Scholze,et al.  Constraining temperature variations over the last millennium by comparing simulated and observed atmospheric CO2 , 2003 .

[59]  J. McConnell,et al.  Continuous ice-core chemical analyses using inductively coupled plasma mass spectrometry. , 2002, Environmental science & technology.

[60]  P. Bergamaschi,et al.  Stable isotopic signature of methane from major sources in Germany , 1993 .

[61]  E. Wada,et al.  Carbon isotope composition of CH4 from rice paddies in Japan , 1991 .

[62]  R. Lyman Ott.,et al.  An introduction to statistical methods and data analysis , 1977 .