Synchronization of the Byrd and Greenland (GISP2/GRIP) Records: Readme file --------------------------------------------------------------------- World Data Center for Paleoclimatology, Boulder and NOAA Paleoclimatology Program --------------------------------------------------------------------- NOTE: PLEASE CITE ORIGINAL REFERENCE WHEN USING THIS DATA!!!!! NAME OF DATA SET: Synchronization of the Byrd and Greenland (GISP2/GRIP) Records CONTRIBUTORS: Thomas Blunier, Princeton University, and Edward J. Brook, Washington State University. IGBP PAGES/WDCA CONTRIBUTION SERIES NUMBER: 2001-003 SUGGESTED DATA CITATION: Blunier T., and E.J. Brook, 2001, Synchronization of the Byrd and Greenland (GISP2/GRIP) Records. IGBP PAGES/World Data Center-A for Paleoclimatology Data Contribution Series #2001-003. NOAA/NGDC Paleoclimatology Program, Boulder CO, USA. ORIGINAL REFERENCE: Blunier, T. and E.J. Brook, 2001, Timing of millennial-scale climate change in Antarctica and Greenland during the last glacial period, Science, 291, 109-112, 5 January 2001. ADDITIONAL REFERENCES: GRIP isotopic record: ===================== Dansgaard, W., S.J. Johnsen, H.B. Clausen, D. Dahl-Jensen, N.S. Gundestrup, C.U. Hammer, C.S. Hvidberg, J.P. Steffensen, A.E. Sveinbjörnsdottir, J. Jouzel, and G. Bond, Evidence for general instability of past climate from a 250-kyr ice-core record, Nature, 364, 218-220, 1993. Johnsen, S.J., and W. Dansgaard, On flow model dating of stable isotope records from Greenland ice cores, in The Last Deglaciation: Absolute and Radiocarbon Chronologies. NATO ASI series, edited by E. Bard, and W.S. Broecker, pp. 13-24, Springer Verlag, 1992. Johnsen, S., D. Dahl-Jensen, W. Dansgaard, and N. Gundestrup, Greenland palaeotemperatures derived from GRIP bore hole temperature and ice core isotope profiles, Tellus, 47B, 624-629, 1995. GISP2 isotopic record: ===================== Grootes, P.M., and M. Stuiver, Oxygen 18/16 variability in Greenland snow and ice with 10^3 to 10^5-year time resolution. J Geophys. Res., 102, 26455-26470, 1997. Stuiver, M., P.M. Grootes, and T.F. Braziunas, The GISP2 d18O climate record of the past 16,500 years and the role of the sun, ocean and volcanoes. Quat. Res., 44, 341-354, 1995. Meese, D.A., R.B. Alley, R.J. Fiacco, M.S. Germani, A.J. Gow, P.M. Grootes, M. Illing, P.A. Mayewski, M.C. Morrison, M. Ram, K.C. Taylor, Q. Yang, and G.A. Zielinski, Preliminary depth-agescale of the GISP2 ice core. Special CRREL Report, 94-1, US, 1994. Steig, E.J., P.M. Grootes, and M. Stuiver, Seasonal precipitaion timing and ice core records. Science, 266, 1885-1886, 1994. Grootes, P.M., M. Stuiver, J.W.C. White, S.J. Johnsen, and J. Jouzel, Comparison of oxygen isotope records from the GISP2 and GRIP Greenland ice cores. Nature, 366, 552-554, 1993. Byrd isotopic record: ===================== Johnsen, S.J., W. Dansgaard, H.B. Clausen, and C.C. Langway, Jr, Oxygen isotope profiles through the Antarctic and Greenland ice sheets, Nature, 235 (5339), 429-434, 1972. GRIP CH4 data: ========= Dällenbach, A., T. Blunier, J. Flückiger, B. Stauffer, J. Chappellaz, and D. Raynaud, Changes in the atmospheric CH4 gradient between Greenland and Antarctica during the Last Glacial and the transition to the Holocene, Geophys. Res. Lett., 27 (7), 1005-1008, 2000. Blunier, T., J. Chappellaz, J. Schwander, B. Stauffer, and D. Raynaud, Variations in atmospheric methane concentration during the Holocene epoch, Nature, 374, 46-49, 1995. Chappellaz, J., T. Blunier, D. Raynaud, J.M. Barnola, J. Schwander, and B. Stauffer, Synchronous changes in atmospheric CH4 and Greenland climate between 40 and 8 kyr BP, Nature, 366, 443- 445, 1993. GISP2 CH4 data: ========= Brook, E.J., S. Harder, J. Severinghaus, E.J. Steig, and M. Sucher, On the origin and timing of rapid changes in atmospheric methane during the last glacial period, Global Biogeochem. Cycles, 14 (2), 559-572, 2000. Byrd CH4 data: ========= Blunier, T. and E.J. Brook, Timing of millennial-scale climate change in Antarctica and Greenland during the last glacial period, Science, 291, 109-112, 2001. Blunier, T., J. Chappellaz, J. Schwander, A. Dällenbach, B. Stauffer, T.F. Stocker, D. Raynaud, J. Jouzel, H.B. Clausen, C.U. Hammer, and S.J. Johnsen, Asynchrony of Antarctic and Greenland climate change during the last glacial period, Nature, 394, 739-743, 1998. LAST UPDATE: 1/2001 (Original Receipt by WDCA Paleo) GEOGRAPHIC REGION: Global PERIOD OF RECORD: 10 -90 KYrBP LIST OF FILES: Readme.Blunier2001.txt(this file), iso_blunier01.xls, ch4_blunier01.xls (Microsoft Excel format) , iso_blunier01.txt, ch4_blunier01.txt (tab-delimited ASCII format). DESCRIPTION: The data archived here were used for Figure 1 of Blunier and Brook, Timing of millennial-scale climate change in Antarctica and Greenland during the last glacial period, Science, 291, 109-112, 2001. This paper should be cited when referring to the synchronized Byrd time scale and the Byrd methane data for the time period >50 ka. References to the original d18O and CH4 data are given below. Content: ******** Filenames: iso_blunier01.txt and iso_blunier01.xls Byrd isotopic data on the synchronised time scale discussed in Blunier and Brook, 2001. Data is given on both GRIP and GISP2 original time scales. Isotopic records of the GRIP and GISP2 data are given on their respective original time scales. Specific time scale references are given below. Note: 0 BP is 1989 and 1950 for GRIP and GISP2, respectively. The file contains ten columns: Column 1: GRIP depth (meters below the surface) Column 2: GRIP d18O (‰) Column 3: GRIP age (calendar years before 1989) Column 4: GISP2 depth (meters below the surface) Column 5: GISP2 d18O (‰) Column 6: GISP2 age (calendar years before 1950) Column 7: Byrd depth (meters below the surface) Column 8: Byrd d18O (‰) Column 9: Byrd age on the GISP2 time scale(calendar years before 1950) Column 10: Byrd age on the GRIP time scale(calendar years before 1989) Filenames: ch4_blunier01.txt ch4_blunier01.xls GRIP, GISP2 and Byrd CH4 data used for the synchronisation. All data is given on the GRIP and on the GISP2 time scale. The file contains twelve columns: Column 1: GRIP depth (meters below the surface) Column 2: GRIP CH4 concentration (ppbv, parts per billion by volume) Column 3: Mean age of the trapped air for the GRIP CH4 data on the GISP2 time scale (calendar years Before 1950) Column 4: Mean age of the trapped air for the GRIP CH4 data on the GRIP time scale (calendar years Before 1989) Column 5: GISP2 depth (meters below the surface) Column 6: GISP2 CH4 concentration (ppbv, parts per billion by volume) Column 7: Mean age of the trapped air for the GISP2 CH4 data on the GISP2 time scale (calendar years Before 1950) Column 8: Mean age of the trapped air for the GISP2 CH4 data on the GRIP time scale (calendar years Before 1989) Column 9: Byrd depth (meters below the surface) Column 10: Byrd CH4 concentration (ppbv, parts per billion by volume) Column 11: Mean age of the trapped air for the Byrd CH4 data on the GISP2 time scale (calendar years Before 1950) Column 12: Mean age of the trapped air for the Byrd CH4 data on the GRIP time scale (calendar years Before 1989) GRIP/GISP2 (Greenland IceCore Project/Greenland Ice Sheet Project) ================================ For a description of the GRIP/GISP2 reference time scales please refer to the Greenland Summit Ice Cores CD-ROM which was created in conjunction with the Journal of Geophysical Research (JGR) Joint Issue (Atmospheres and Oceans) on the Greenland Ice Cores, vol. 102, C12 1997. A copy of the CD can be found at www.ngdc.noaa.gov/paleo/icecore/greenland/summit/index.htm. The complete records can also be found at that location. Antarctic synchronised time scales: =================================== The Antarctic records are synchronised to the GRIP/GISP2 record via the fast variations of the global methane signal. The uncertainty of this synchronisation is time dependent (see Blunier and Brook, 2000 for details). Warnings: ========= The time scales used here constrain the relative timing of events in Greenland and Antarctica. However, none of the time scales used here are absolute time scales. Therefore, caution is warranted in using them for comparison to other types of chronologies, or calculations of glaciological parameters like ice accumulation rate. CH4 values ========== CH4 values are mean values where multiple measurements on the same depth levels have been made. The uncertainty (one sigma) is about 10 ppbv.