Timing of Millennial-Scale Climate Change in Antarctica and Greenland During the Last Glacial Period Thomas Blunier and and Edward J. Brook

- Thomas Blunier, Princeton University, Geosciences, Guyot Hall, Princeton NJ 08544, USA

Tel office: +1 609 258 2756; Fax: +1 609 258 0796;

E-mail: blunier@princeton.edu

- Edward J. Brook, Department of Geology, Washington State University, 14204 NE Salmon Creek Ave, Vancouver, WA 98686, USA

Tel office: +1 360 546 9762; Fax: +1 360546 9037;

E-mail: brook@vancouver.wsu.edu

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, 2000. 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:

Filename: iso_bl00.txt Byrd isotopic data on the synchronised time scale discussed in Blunier and Brook, 2000. 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 (⁰/₀₀)
Column 3: GRIP age (calendar years before 1989)
Column 4: GISP2 depth (meters below the surface)
Column 5: GISP2 d¹⁸O (⁰/₀₀)

Column 6: GISP2 age (calendar years before 1950)
Column 7: Byrd depth (meters below the surface)
Column 8: Byrd d¹⁸O (⁰/₀₀)
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)

Filename: ch4_bl00.txt
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. References:

For the synchronisation of Antarctic isotopes to the GRIP/GISP2 isotopic record:

Blunier, T. and Brook, E.J, Timing of millennial-scale climate change in Antarctica and Greenland during the last glacial period, Science, 2000 in the press.

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 2000.

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.

Supplemental Table 1. Uncertainty of the synchronization of the Byrd record for individual Dansgaard-Oeschger events.
D-O event no.	Corres-ponding Antarctic warming	Start of D-O events on the GISP2 ice time scale (ka)	Uncertainty of the Byrd versus the GISP2 gas time scale (years)	Uncertainty of the Byrd versus the GISP2 ice time scale (years)
YD - 1	ACR	11.6 - 14.7	±200	±300
2		23.4	±300	±400
3		27.8	±200	±300
4		29.0	±200	±300
5		32.4	±200	±300
6		33.7	±200	±300
7		35.3	±200	±300
8	A1	38.4	±200	±300
9		40.3	±200	±300
10		41.1	±200	±300
11		42.5	±200	±300
12	A2	45.4	±200	±300
13		47.2	-	-
14	A3	52.0	±450	±500
15		53.8	±200	±300
16	A4	56.6	±450	±500
17		58.2	±200	±300
18		62.1	-	-
19	A5	67.8	±600*	±650
20	A6	71.7	±600*	±650
21	A7	84.0	±700	±750
*Based on d18O of O2. Obtained by adding in quadrature the uncertainty of the CH4 synchronization (column 4) and the uncertainties for the GISP2 and Byrd Dages taken as ±100 years and ±200 years, respectively.

• To view Supplemental Table 2 in excel format click here

• To view Supplemental Table 3 in excel format click here