Eastern Tropical Pacific Foraminiferal Mg/Ca and SST Reconstruction --------------------------------------------------------------------- NOAA Paleoclimatology Program and World Data Center for Paleoclimatology, Boulder --------------------------------------------------------------------- NOTE: PLEASE CITE ORIGINAL REFERENCES WHEN USING THIS DATA!!!!! NAME OF DATA SET: Eastern Tropical Pacific Foraminiferal Mg/Ca and SST Reconstruction LAST UPDATE: 6/2004 (Original Receipt by WDC Paleo) CONTRIBUTOR: David Lea, University of California, Santa Barbara IGBP PAGES/WDCA CONTRIBUTION SERIES NUMBER: 2004-028 SUGGESTED DATA CITATION: Lea, D. W., 2004. Eastern Tropical Pacific Foraminiferal Mg/Ca and SST Reconstruction, IGBP PAGES/World Data Center for Paleoclimatology Data Contribution Series #2004-028. NOAA/NGDC Paleoclimatology Program, Boulder, CO, USA. ORIGINAL REFERENCE: Lea, D. W.. 2004. The 100,000 year cycle in tropical SST, greenhouse forcing, and climate sensitivity. Journal of Climate 17(11), 2170-2179. ADDITIONAL REFERENCES: Dekens, P. S., D. W. Lea, D. K. Pak, and H. J. Spero. 2002. Core top calibration of Mg/Ca in tropical foraminifera: Refining paleo- temperature estimation. Geochem. Geophys. Geosyst., 3, 1022, doi:10.1029/2001GC000200 Lea, D. W., D. K. Pak, and H. J. Spero. 2000. Climate impact of late quaternary equatorial Pacific sea surface temperature variations. Science, v.289, 1719–1724. Shackleton, N. J.. 2000. The 100,000-year ice-age cycle identified and found to lag temperature, carbon dioxide, and orbital eccentricity. Science, v.289, 1897–1902. ABSTRACT: The key scientific uncertainty in the global warming debate is the equilibrium climate sensitivity. Coupled atmosphere–ocean general circulation models predict a wide range of equilibrium climate sensitivities, with a consequently large spread of societal implications. Comparison of models with instrumental data has not been able to reduce the uncertainty in climate sensitivity. An alternative way to gauge equilibrium climate sensitivity is to use paleoclimatic data. Two recent advances, the development and application of proxy recorders of tropical sea surface temperature (SST) and the synchronization of the deep-sea and Antarctic ice-core time scales, make it possible to directly relate past changes in tropical SST to atmospheric carbon dioxide (CO2) levels. The strong correspondence of a proxy SST record from the eastern equatorial Pacific and the Vostok CO2 record suggests that varying atmospheric carbon dioxide is the dominant control on tropical climate on orbital time scales. This effect is especially pronounced at the 100,000-yr cycle. Calibration of the CO2 influence via tropical SST variability indicates a tropical climate sensitivity of 4.4°–5.6°C (errors estimated at ± 1.0°C) for a doubling of atmospheric CO2 concentration. This result suggests that the equilibrium response of tropical climate to atmospheric CO2 changes is likely to be similar to the upper end of available global predictions from coupled models. FUNDING SOURCES: USA NSF MG & G, Guggenheim and Leverhulme Foundations GEOGRAPHIC REGION: Cocos Ridge, Eastern tropical Pacific PERIOD OF RECORD: 361 KYrBP - present DESCRIPTION: Cocos Ridge, Eastern tropical Pacific, foraminiferal Mg/Ca and SST reconstruction. Mg/Ca data on cleaned G. ruber shells by ICP-MS, 417 individual data points from Lea et al. 2000, and 76 new data points from 39 depth intervals, total data points 493, total depth intervals 208. SST estimates based on depth/basin-corrected calibration in Dekens et al., 2002: SST(deg C) = LN((Mg/Ca-m)/0.38)/0.09+0.61*2.348+1.6 Core TR163-19, Cocos Ridge lat: 2°15.5'N long: 90°57.1'W 2348m water depth Data precision: Mg/Ca, ±2.1%; SST (est.), ±0.6°C core site is NW flank of Cocos Ridge, collected in February 1975, core is 10.3m long, archived at University of Rhode Island Conversion of core depth to age is based on the timescale for core V19-30 in Shackleton (2000). Benthic O18 from TR163-19 was tied to V19-30 O18. A calibrated radiocarbon age was used for the core-top only. DATA: 1. Age model Event Depth-cm age-ky Top 1 1.04 2.0 44 12 3.0 124 30 3.3 239 55 5.0 284 71 5e 389 124 6.0 414 131 6.5 529 171 7.0 569 191 7.4 to 7 679 230 8.0 704 245 9.0 799 279 10.0 959 336 10.2 999 344 - 1029 361 2. Mg/Ca and SST Depth (cm), Age (ky), Mg/Ca (mmol/mol), SST (°C) Depth Age-ky Mg/Ca-m SST-deg C 1 1 2.999 26 4 1.8 2.86 25.5 9 3.1 3.123 26.4 14 4.4 3.017 26.1 19 5.6 3.061 26.2 24 6.9 3.095 26.3 29 8.2 3.326 27.1 34 9.5 2.989 25.9 39 10.7 2.852 25.4 44 12 2.881 25.5 49 13.1 2.783 25.2 54 14.3 2.745 25 59 15.4 2.627 24.5 64 16.5 2.613 24.5 69 17.6 2.309 23.1 74 18.8 2.356 23.3 79 19.9 2.466 23.8 84 21 2.3 23 89 22.1 2.447 23.7 94 23.3 2.424 23.6 99 24.4 2.441 23.7 104 25.5 2.215 22.6 109 26.6 2.413 23.6 114 27.8 2.291 23 119 28.9 2.254 22.8 124 30 2.361 23.3 129 31.1 2.683 24.7 134 32.2 2.633 24.5 139 33.3 2.467 23.8 144 34.3 2.576 24.3 149 35.4 2.469 23.8 154 36.5 2.601 24.4 159 37.6 2.205 22.6 164 38.7 2.493 23.9 169 39.8 2.58 24.3 174 40.9 2.595 24.4 179 42 2.441 23.7 184 43 2.458 23.8 189 44.1 2.577 24.3 194 45.2 2.601 24.4 199 46.3 2.622 24.5 204 47.4 2.659 24.7 209 48.5 2.785 25.2 214 49.6 2.669 24.7 220 50.9 2.441 23.7 224 51.7 2.493 23.9 229 52.8 2.608 24.4 234 53.9 2.715 24.9 239 55 2.63 24.5 244 56.8 2.556 24.2 249 58.6 2.521 24.1 254 60.3 2.527 24.1 259 62.1 2.665 24.7 264 63.9 2.563 24.2 269 65.7 2.208 22.6 274 67.4 2.416 23.6 279 69.2 2.373 23.4 284 71 2.555 24.2 289 73.5 2.529 24.1 294 76 2.741 25 299 78.6 2.767 25.1 304 81.1 2.852 25.4 309 83.6 2.896 25.6 314 86.1 2.603 24.4 319 88.7 2.525 24.1 324 91.2 2.516 24 329 93.7 2.607 24.4 334 96.2 2.775 25.1 339 98.8 2.939 25.8 344 101.3 2.903 25.6 349 103.8 3.017 26.1 354 106.3 2.927 25.7 359 108.9 2.849 25.4 364 111.4 2.725 24.9 369 113.9 2.757 25.1 374 116.4 2.698 24.8 379 119 3.13 26.5 384 121.5 3.091 26.3 389 124 3.385 27.3 394 125.4 3.59 28 399 126.8 3.621 28.1 404 128.2 3.614 28.1 409 129.6 3.158 26.6 414 131 3.367 27.3 419 132.7 3.058 26.2 423 134.1 2.796 25.2 429 136.2 2.522 24.1 434 138 2.605 24.4 439 139.7 2.491 23.9 444 141.4 2.623 24.5 449 143.2 2.419 23.6 454 144.9 2.562 24.2 459 146.7 2.573 24.3 464 148.4 2.81 25.3 469 150.1 2.501 24 474 151.9 2.56 24.2 479 153.6 2.306 23.1 484 155.3 2.375 23.4 489 157.1 2.246 22.8 494 158.8 2.54 24.1 499 160.6 2.553 24.2 504 162.3 2.578 24.3 509 164 2.382 23.4 512.8 165.3 2.483 23.9 519 167.5 2.302 23 524 169.3 2.56 24.2 529 171 2.444 23.7 534 173.5 2.519 24 539 176 2.343 23.2 544 178.5 2.748 25 549 181 2.419 23.6 554 183.5 2.575 24.3 559 186 2.332 23.2 564 188.5 2.645 24.6 569 191 2.438 23.7 574 192.8 2.605 24.4 579 194.5 2.569 24.3 584 196.3 2.942 25.8 589 198.1 2.784 25.2 594 199.9 3.089 26.3 599 201.6 2.768 25.1 604 203.4 2.629 24.5 609 205.2 2.601 24.4 614 207 2.744 25 619 208.7 2.765 25.1 624 210.5 3.019 26.1 629 212.3 3.115 26.4 634 214 3.183 26.6 639 215.8 3.025 26.1 644 217.6 2.816 25.3 649 219.4 2.533 24.1 654 221.1 2.524 24.1 659 222.9 2.402 23.5 664 224.7 2.816 25.3 669 226.5 2.615 24.5 674 228.2 2.669 24.7 679 230 2.753 25 684 233 3.135 26.5 689 236 3.172 26.6 694 239 3.346 27.2 699 242 3.52 27.8 704 245 3.215 26.8 709 246.8 2.884 25.6 714 248.6 2.724 24.9 719 250.4 2.65 24.6 724 252.2 2.352 23.3 729 253.9 2.427 23.6 734 255.7 2.385 23.4 739 257.5 2.46 23.8 743 259 2.384 23.4 744 259.3 2.476 23.9 749 261.1 2.441 23.7 754 262.9 2.425 23.6 759 264.7 2.445 23.7 764 266.5 2.495 23.9 769 268.3 2.278 22.9 774 270.1 2.333 23.2 779 271.8 2.536 24.1 784 273.6 2.337 23.2 789 275.4 2.331 23.2 794 277.2 2.414 23.6 799 279 2.723 24.9 804 280.8 2.468 23.8 809 282.6 2.824 25.3 814 284.3 2.839 25.4 819 286.1 3.102 26.4 824 287.9 3.071 26.3 829 289.7 3.231 26.8 834 291.5 2.8 25.2 839 293.3 2.296 23 844 295 2.385 23.4 849 296.8 2.55 24.2 854 298.6 2.388 23.5 859 300.4 2.643 24.6 864 302.2 2.665 24.7 869 303.9 2.689 24.8 874 305.7 2.636 24.6 879 307.5 2.795 25.2 884 309.3 2.846 25.4 889 311.1 2.775 25.1 894 312.8 2.919 25.7 899 314.6 3.022 26.1 904 316.4 2.772 25.1 909 318.2 2.794 25.2 914 320 2.894 25.6 919 321.8 2.884 25.6 924 323.5 2.885 25.6 929 325.3 3.355 27.2 934 327.1 3.174 26.6 939 328.9 3.429 27.5 944 330.7 3.088 26.3 949 332.4 3.509 27.7 954 334.2 3.31 27.1 959 336 3.535 27.8 964 337 3.113 26.4 969 338 3.177 26.6 974 339 2.858 25.5 979 340 2.83 25.3 984 341 2.674 24.7 989 342 2.753 25 994 343 2.588 24.3 999 344 2.512 24 1004 346.8 2.484 23.9 1009 349.7 2.668 24.7 1014 352.5 2.518 24 1019 355.3 2.408 23.5 1024 358.2 2.329 23.2 1029 361 2.341 23.2