GISP2 Methane Concentrations REFERENCE: Brook, E.J., T. Sowers, and J. Orchardo. 1996. Rapid variations in atmospheric methane concentration during the past 110,000 years. Science 273:1087-1091. DATA DESCRIPTION: Gas ages were calculated according to the methods described in Brook et al. 1996, and are subject to change. Ice ages were calculated by by linear interpolation from the Meese et al. timescale. DATA: Depth CH4 Gas Age Ice Age Midpoint (m) (ppbV) (yr BP 1950) (yr BP 1950) 116.3 739 133 337 116.7 737 135 339 117.3 753 138 341 117.6 754 140 343 147.1 730 273 466 149.3 701 284 477 151.3 694 294 486 214.3 700 565 760 274.1 715 830 1019 314.1 663 1007 1194 393 665 1369 1566 435 651 1584 1780 455 654 1679 1878 475.1 637 1779 1973 535.1 626 2088 2280 615.1 596 2510 2704 634.1 615 2615 2809 655.1 665 2730 2922 736.1 647 3198 3388 755.1 590 3310 3503 874.1 609 4035 4232 919.7 598 4328 4524 991.1 588 4802 4995 1014.6 581 4965 5157 1074.2 592 5387 5586 1134.9 579 5855 6052 1235.5 603 6659 6854 1253.9 654 6816 7007 1334.9 634 7510 7702 1354.9 621 7688 7877 1375.1 613 7867 8057 1415.1 566 8233 8437 1455.1 662 8631 8819 1475.1 727 8828 9018 1495 653 9026 9216 1516.1 659 9243 9440 1535 682 9451 9654 1554 710 9664 9874 1575.1 749 9914 10123 1608.1 742 10311 10556 1615 708 10399 10654 1635 716 10672 10942 1655 732 10957 11251 1675.1 738 11261 11592 1681.9 681 11407 11782 1687.9 709 11505 11987 1688.2 737 11510 11998 1691.2 751 11557 12107 1693 755 11589 12175 1695.1 769 11626 12246 1695.7 686 11641 12271 1696.1 738 11652 12289 1697 693 11675 12323 1698 625 11703 12363 1699 591 11729 12400 1700.1 536 11761 12441 1701.5 534 11805 12493 1702 489 11822 12512 1704.1 485 11901 12595 1706.1 481 11972 12672 1708.5 525 12054 12760 1711.2 458 12146 12856 1715.1 510 12255 12957 1721.9 497 12500 13105 1728.7 585 12822 13298 1735.1 703 12991 13446 1741.9 618 13151 13585 1755 675 13498 13864 1768.2 666 13783 14153 1775.1 651 13921 14282 1789.2 661 14228 14513 1794.2 661 14324 14595 1795.1 667 14343 14612 1801.2 622 14486 14793 1815.1 593 14718 15299 1828.1 482 15177 15833 1835.1 481 15440 16125 1855.1 462 16225 16885 1868.2 450 16767 17429 1878.2 404 17263 17892 1895.1 406 18190 18734 1902.1 380 18587 19092 1908 356 18864 19344 1915.1 396 19163 19675 1935.1 394 20069 20638 1975.1 413 22123 22839 1995 425 23123 23948 2002 395 23298 24363 2015 414 24288 25191 2035.1 384 25786 26551 2042 393 26256 26980 2048 362 26672 27381 2061 389 27653 28217 2068 459 27844 28649 2088 490 28886 29840 2102 412 29549 30745 2108 396 29987 31140 2115.1 466 30460 31587 2122 427 31326 32003 2135.1 525 32062 32852 2148.1 462 33244 33728 2155.1 542 33452 34192 2162 430 33692 34591 2168.1 443 34213 34888 2175.1 590 34737 35190 2188.1 583 35072 35949 2195.1 444 35334 36333 2202 461 36112 36709 2215.1 577 37041 37420 2224 554 37595 37930 2228.1 571 37868 38208 2234 560 38142 38565 2235 623 38166 38639 2242 610 38349 39179 2246 466 38619 39513 2249.9 460 38913 39844 2252 463 39090 40006 2254 403 39291 40134 2256 461 39521 40255 2265.9 471 40043 40732 2271.9 442 40415 41005 2277.9 489 40800 41269 2281.9 500 40910 41491 2287.9 433 41094 41796 2293.9 408 41590 42110 2297.9 458 41873 42304 2304 486 42162 42581 2309.9 514 42305 42961 2313.9 474 42406 43197 2319.9 414 42880 43527 2323.9 434 43207 43764 2325.9 474 43331 43881 2327.9 439 43470 43997 2330 470 43607 44111 2331.9 431 43725 44205 2333.9 473 43836 44295 2335.9 497 43958 44388 2337.9 478 44087 44487 2339.9 478 44196 44579 2341.9 482 44296 44671 2343.9 487 44382 44757 2345.9 514 44477 44846 2347.9 491 44580 44936 2349.9 489 44684 45024 2351.9 534 44776 45103 2355.9 511 44967 45279 2359.9 508 45110 45467 2363.9 533 45206 45763 2367.9 528 45340 46072 2373.9 460 45799 46543 2378 454 46195 46880 2383.9 450 46685 47357 2399.9 486 47634 48631 2405.9 462 48047 49145 2409.9 482 48308 49507 2416 515 48748 50016 2421.9 501 49132 50482 2425.9 527 49386 50829 2431.9 536 49925 51357 2437.9 548 50461 51890 2441.9 548 50777 52203 2453.9 546 51778 53162 2453.9 533 51778 53162 2458 555 52012 53467 2461.9 515 52434 53785 2465.9 438 53080 54095 2470 493 53568 54431 2471.9 561 53743 54590 2473.9 549 53988 54756 2481.8 538 55134 55426 2485.9 547 55615 55747 2492 581 56305 56229 2493.9 573 56456 56394 2497.9 629 56840 56739 2499.9 562 57147 56922 2501.9 481 57396 57099 2503.9 592 57591 57275 2506 597 57794 57468 2507.9 602 57954 57638 2510 507 58077 57830 2511.9 589 58212 57997 2513.9 452 58425 58164 2515.9 402 58664 58330 2518 461 58921 58509 2519.9 435 59141 58671 2521.9 466 59370 58850 2525.9 489 59777 59200 2530 450 60327 59543 2532 460 60778 59715 2533.9 454 61218 59874 2534.9 476 61422 59953 2537.9 521 61696 60187 2539.9 538 61817 60342 2541.9 469 61940 60502 2543.9 464 62092 60668 2545.9 524 62300 60829 2547.9 452 62584 60997 2549.9 504 62874 61161 2551.9 432 63146 61361 2553.9 512 63373 61624 2555.9 490 63564 61916 2557.9 457 63817 62183 2559.9 490 64241 62468 2561.9 464 64873 62758 2563.9 512 65263 63067 2565.9 467 65438 63395 2567.9 509 65691 63764 2569.9 448 66233 64143 2571.9 446 66741 64509 2573.9 474 67037 64864 2577.9 488 67582 65520 2581.9 506 68125 66149 2585.9 488 68413 66878 2589.9 453 68471 67634 2594 454 69736 68413 2597.9 463 70519 69177 2599.9 467 70852 69567 2601.9 440 71186 69943 2605.9 512 71824 70727 2607.9 457 72146 71116 2609.9 472 72441 71508 2614 497 72747 72310 2617.9 448 72998 73105 2619.9 416 73664 73510 2621.9 454 74118 73888 2626 443 74820 74725 2629.9 577 75482 75536 2631.9 475 75778 75933 2633.9 461 76097 76325 2637.9 573 76739 77107 2639.9 510 77069 77493 2641.9 506 77372 77859 2643.9 522 77686 78223 2645.9 514 78032 78601 2649.9 574 78708 79319 2651.9 559 79040 79700 2653.9 590 79406 80083 2655.9 580 79779 80453 2657.9 577 80156 80824 2659.9 591 80543 81182 2661.9 591 80924 81550 2664 649 81326 81960 2666.9 639 81890 82506 2667.9 726 82083 82699 2671.9 710 82868 83447 2673.9 666 83283 83844 2675.9 736 83624 84249 2677.9 710 83956 84633 2679.9 505 84347 85022 2682 464 84725 85459 2685.9 462 85495 86267 2688 526 85889 86707 2689.9 462 86293 87079 2691.9 449 86876 87479 2693.9 512 87439 87870 2696 494 87939 88285 2697.9 505 88382 88654 2699.9 487 88861 89064 2701.9 534 89322 89492 2703.9 495 89730 89915 2705.9 447 90134 90328 2707.9 444 90580 90745 2709.9 449 91026 91150 2711.9 443 91487 91549 2713.9 430 91983 91953 2715.9 470 92477 92363 2718 488 93012 92784 2719.9 525 93529 93166 2721.9 430 94051 93565 2723.9 464 94582 93974 2725.9 476 95101 94407 2729.9 528 96140 95283 2731.9 513 96687 95707 2733.9 535 97215 96132 2736 588 97745 96562 2739.9 584 98697 97397 2741.9 572 99145 97823 2744 548 99610 98264 2745.9 566 99969 98648 2748 561 100315 99078 2750 635 100614 99515 2751.9 640 100958 99905 2753.9 594 101369 100307 2756 502 101794 100725 2758 578 102158 101135 2759.9 643 102507 101534 2762 542 102939 101990 2764 447 103333 102425 2766 514 103757 102855 2768 501 104184 103301 2769.9 471 104541 103741 2772 512 104933 104202 2773.9 486 105264 104617 2775.9 487 105572 105081 2779.9 481 106268 106010 2781.9 475 106624 106488 2783.9 452 106957 106964 2785.9 536 107322 107430 2787.9 503 107708 107898 2789.9 557 108116 108360 2792 512 108531 108856 2793.5 570 108655 109214 2795.9 496 108847 109767 2797.9 561 109007 110218 2799.9 500 109175 110671 2802 675 109535 111167 2803.9 644 109808 111595 2806 656 110111 112078 2808 495 110399 112545