Precession phasing offset between Indian summer monsoon and Arabian Sea productivity linked to changes in Atlantic overturning circulation

Paleoceanography

Volumn 25, Issue 3, 2010, Pages

  Ziegler, Martin ^a,d   Lourens, Lucas J ^a   Tuenter, Erik ^b   Hilgen, Frits ^a   Reichart, Gert Jan ^a   Weber, Nanne ^c  

^a UTRECHT UNIVERSITY   (Netherlands)

^b UTRECHT UNIVERSITY   (Netherlands)

^c ROYAL NETHERLANDS METEOROLOGICAL INSTITUTE KNMI   (Netherlands)

^d Doherty Earth Observatory of Columbia University   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

CLIMATE MODELING; LAST GLACIAL; NORTHERN HEMISPHERE; NUTRIENT UPTAKE; OVERTURN; OXYGEN ISOTOPE; PALEOCLIMATE; PALEOECOLOGY; PRECESSION; PRIMARY PRODUCTION; SPELEOTHEM;

ARABIAN SEA; ATLANTIC OCEAN; CHINA; INDIAN OCEAN;

FORAMINIFERA;

EID: 77957607054     PISSN: 08838305     EISSN: None     Source Type: Journal    
DOI: 10.1029/2009PA001884     Document Type: Article

References (82)

1. Altabet, M. A., D. W. Murray, and W. L. Prell (1999), Climatically linked oscillations in Arabian Sea denitrification over the past 1 m.y.: Implications for the marine N cycle, Paleoceanography, 14, 732-743, doi:10.1029/1999PA900035. (Pubitemid 30168138)
2. Altabet, M. A., M. J. Higginson, and D. W. Murray (2002), The effect of millennial-scale changes in Arabian Sea denitrification on atmospheric CO 2, Nature, 415, 159-162, doi:10.1038/415159a. (Pubitemid 34059514)
3. Antoine, D., J.-M. André, and A. Morel (1996), Oceanic primary production: 2. Estimation at global scale from satellite (coastal zone color scanner) chlorophyll, Global Biogeochem. Cycles, 10(1), 57-69, doi:10.1029/95GB02832. (Pubitemid 26475461)
4. Beaufort, L., T. de Garidel-Thoron, A. C. Mix, and N. G. Pisias (2001), ENSO-like forcing on oceanic primary production during the Late Pleistocene, Science, 293(5539), 2440-2444, doi:10.1126/science.293.5539.2440. (Pubitemid 32917322)
5. Bintanja, R., R. S. W. van de Waal, and J. Oerlemans (2005), Modelled atmospheric temperatures and global sea levels over the past million years, Nature, 437, 125-128, doi:10.1038/nature03975. (Pubitemid 41613437)
6. Calov, R., A. Ganopolski, V. Petoukhov, M. Claussen, V. Brovkin, and C. Kubatzki (2005), Transient simulation of the last glacial inception. Part II: Sensitivity and feedback analysis, Clim. Dyn., 24, 563-576. (Pubitemid 41166832)
7. Chapman, M. R., and N. J. Shackleton (1998), Millennial-scale fluctuations in North Atlantic heat flux during the last 150,000 years, Earth Planet. Sci. Lett., 159, 57-70, doi:10.1016/S0012-821X(98)00068-5. (Pubitemid 28456610)
8. Chapman, M. R., and N. J. Shackleton (1999), Global ice-volume fluctuations, North Atlantic ice-rafting events, and deep-ocean circulation changes between 130 and 70 ka, Geology, 27 (9), 795-798, doi:10.1130/0091- 7613(1999) 0272.3.CO;2.
9. Chen, M.-T., L.-J. Shiau, P.-S. Yu, T.-C. Chiu, Y.-G. Chen, and K.-Y. Wei (2003), 500 000-year records of carbonate, organic carbon, and foraminiferal sea-surface temperature from the southeastern South China Sea (near Palawan Island), Palaeogeogr. Palaeoclimatol. Palaeoecol., 197, 113-131, doi:10.1016/S0031-0182(03)00389-4. (Pubitemid 36946786)
10. Clemens, S. C., and W. L. Prell (2003), A 350,000 year summer-monsoon multi-proxy stack from the Owen Ridge, northern Arabian Sea, Mar. Geol., 201(1-3), 35-51, doi:10.1016/S0025-3227(03)00207-X. (Pubitemid 37207627)
11. Clemens, S., W. Prell, D. Murray, G. Shimmield, and G. Weedon (1991), Forcing mechanisms of the Indian Ocean monsoon, Nature, 353, 720-725, doi:10.1038/353720a0.
12. Clemens, S. C., D. W. Murray, and W. L. Prell (1996), Nonstationary phase of the Plio- Pleistocene Asian monsoon, Science, 274(5289), 943-948, doi:10.1126/science.274.5289.943. (Pubitemid 26398408)
13. Clement, A. C., and M. Cane (1999), A role for the tropical Pacific coupled ocean-atmosphere system on Milankovitch and millennial timescales. Part I: A modeling study of tropical Pacific variability, in Mechanisms of Global Climate Change at Millennial Time Scales, Geophys. Monogr. Ser., vol.112, edited by P. U. Clark, R. S. Webb, and L. D. Keigwin, pp. 363-372, AGU, Washington, D. C.
14. den Dulk, M., G. J. Reichart, S. van Heyst, W. J. Zachariasse, and G. J. Van der Zwaan (2000), Benthic foraminifera as proxies of organic matter flux and bottom water oxygenation? A case history from the northern Arabian Sea, Palaeogeogr. Palaeoclimatol. Palaeoecol., 161, 337-359, doi:10.1016/S0031- 0182(00) 00074-2.
15. Drysdale, R. N., G. Zanchetta, J. C. Hellstrom, A. E. Fallick, and J. Zhao (2005), Stalagmite evidence for the onset of the last interglacial in southern Europe at 129 ± 1 ka, Geophys. Res. Lett., 32, L24708, doi:10.1029/2005GL024658. (Pubitemid 43239981)
16. Drysdale, R. N., G. Zanchetta, J. C. Hellstrom, A. E. Fallick, J. McDonald, and I. Cartwright (2007), Stalagmite evidence for the precise timing of North Atlantic cold events during the early last glacial, Geology, 35(1), 77-80, doi:10.1130/G23161A.1. (Pubitemid 46131812)
17. Dutton, A., E. Bard, F. Antonioli, T. M. Esat, K. Lambeck, and M. T. McCulloch (2009), Phasing and amplitude of sea-level and climate change during the penultimate interglacial, Nat. Geosci., 2, 355-359, doi:10.1038/ngeo470.
18. Gallup, C. D., H. Cheng, F. W. Taylor, and R. L. Edwards (2002), Direct determination of the timing of sea level change during Termination II, Science, 295(5553), 310-313, doi:10.1126/science.1065494. (Pubitemid 34074357)
19. Ganopolski, A., S. Rahmstorf, V. Petoukhov, and M. Claussen (1998a), Simulation of modern and glacial climates with a coupled global model of intermediate complexity, Nature, 391, 351-356.
20. Ganopolski, A., C. Kubatzki, M. Claussen, V. Brovkin, and V. Petoukhov (1998b), The influence of vegetation-atmosphere-ocean interaction on climate during the Mid-Holocene, Science, 280(5371), 1916-1919.
21. Ganopolski, A., V. Petoukhov, S. Rahmstorf, V. Brovkin, M. Claussen, A. Eliseev, and C. Kubatzki (2001), CLIMBER-2: A climate system model of intermediate complexity. Part II-Model sensitivity, Clim. Dyn., 17, 735-751, doi:10.1007/s003820000144. (Pubitemid 32863430)
22. Genty, D., D. Blamart, R. Ouahdi, M. Gilmour, A. Baker, J. Jouzel, and S. Van-Exer (2003), Precise dating of Dansgaard-Oeschger climate oscillations in western Europe from stalagmite data, Nature, 421, 833-837, doi:10.1038/ nature01391. (Pubitemid 36254140)
23. Gupta, A. K., M. Das, S. C. Clemens, and B. Mukherjee (2008), Benthic foraminiferal faunal and isotopic changes as recorded in Holocene sediments of the northwest Indian Ocean, Paleoceanography, 23, PA2214, doi:10.1029/ 2007PA001546.
24. Henderson, G. M., and N. C. Slowey (2000), Evidence from U-Th dating against Northern Hemisphere forcing of the penultimate deglaciation, Nature, 404, 61-66, doi:10.1038/35003541. (Pubitemid 30143130)
25. Huguet, C., J.-H. Kim, J. S. Sinninghe Damsté, and S. Schouten (2006), Reconstruction of sea surface temperature variations in the Arabian Sea over the last 23 kyr using organic proxies (TEX86 and U37K′), Paleoceanography, 21, PA3003, doi:10.1029/2005PA001215. (Pubitemid 46781132)
26. Igarashi, Y., and T. Oba (2006), Fluctuations in the East Asian monsoon over the last 144 ka in the northwest Pacific based on a high-resolution pollen analysis of IMAGES core MD01-2421, Quat. Sci. Rev., 25, 1447-1459, doi:10.1016/j.quascirev.2005.11.011. (Pubitemid 44037119)
27. Imbrie, J., J. D. Hays, D. G. Martinson, A. McIntyre, A. C. Mix, J. J. Morley, N. G. Pisias, W. L. Prell, and N. J. Shackleton (1984), The orbital theory of Pleistocene climate: Support from a revised chronology of the marine δ18O record, in Milankovitch and Climate: Part I, edited by A. Berger, pp. 269-305, D. Reidel, Dordrecht, Netherlands.
28. Imbrie, J., et al. (1992), On the structure and origin of major glaciation cycles: 1. Linear responses to Milankovitch forcing, Paleoceanography, 7, 701-738.
29. Imbrie, J., et al. (1993), On the structure and origin of major glaciation cycles: 2. The 100,000- year cycle, Paleoceanography, 8, 699-735, doi:10.1029/93PA02751.
30. Jaeschke, A., M. Ziegler, E. C. Hopmans, G.-J. Reichart, L. J. Lourens, S. Schouten, and J. S. Sinninghe Damsté (2009), Molecular fossil evidence for anaerobic ammonium oxidation in the Arabian Sea over the last glacial cycle, Paleoceanography, 24, PA2202, doi:10.1029/2008PA001712.
31. Jin, L., F. Chen, A. Ganopolski, and M. Claussen (2007), Response of East Asian climate to Dansgaard/Oeschger and Heinrich events in a coupled model of intermediate complexity, J. Geophys. Res., 112, D06117, doi:10.1029/ 2006JD007316. (Pubitemid 46824891)
32. Jung, S. J. A., G. M. Ganssen, and G. R. Davies (2001), Multidecadal variations in the early Holocene outflow of Red Sea water into the Arabian Sea, Paleoceanography, 16, 658-668, doi:10.1029/2000PA000592. (Pubitemid 34137720)
33. Kutzbach, J. E., X. Liu, Z. Liu, and C. Chen (2008), Simulation of the evolutionary response of global summer monsoons to orbital forcing over the past 280,000 years, Clim. Dyn., 30, 567-579, doi:10.1007/s00382-007-0308-z.
34. Leuschner, D. C., and F. Sirocko (2003), Orbital insolation forcing of the Indian Monsoon-A motor for global climate changes?, Palaeogeogr. Palaeoclimatol. Palaeoecol., 197, 83-95, doi:10.1016/S0031-0182(03)00387-0. (Pubitemid 36946784)
35. Lisiecki, L. E., and M. E. Raymo (2005), A Pliocene-Pleistocene stack of 57 globally distributed benthic δ18O records, Paleoceanography, 20, PA1003, doi:10.1029/2004PA001071. (Pubitemid 40865277)
36. Lisiecki, L. E., and M. E. Raymo (2009), Diachronous benthic δ18O responses during late Pleistocene terminations, Paleoceanography, 24, PA3210, doi:10.1029/2009PA001732.
37. Lisiecki, L. E., M. E. Raymo, and W. B. Curry (2008), Atlantic overturning responses to Late Pleistocene climate forcings, Nature, 456, 85-88, doi:10.1038/nature07425.
38. Locarnini, R. A., A. V. Mishonov, J. I. Antonov, T. P. Boyer, and H. E. Garcia (2006), World Ocean Atlas 2005, vol.1, Temperature, NOAA Atlas NESDIS, vol.61, edited by S. Levitus, 182 pp., NOAA, Silver Spring, Md.
39. Loulergue, L., A. Schilt, R. Spahni, V. Masson- Delmotte, T. Blunier, B. Lemieux, J.-M. Barnola, D. Raynaud, T. F. Stocker, and J. Chappellaz (2008), Orbital and millennialscale features of atmospheric CH4 over the past 800,000 years, Nature, 453, 383-386, doi:10.1038/nature06950. (Pubitemid 351693132)
40. Lourens, L. J. (2004), Revised tuning of Ocean Drilling Program Site 964 and KC01B (Mediterranean) and implications for the d18O, tephra, calcareous nannofossil, and geomagnetic reversal chronologies of the past 1.1 Myr, Paleoceanography, 19, PA3010, doi:10.1029/2003PA000997. (Pubitemid 40055430)
41. Lourens, L. J., A. Antonarakou, F. J. Hilgen, A. A. M. Van Hoof, C. Vergnaud-Grazzini, and W. J. Zachariasse (1996), Evaluation of the Plio-Pleistocene astronomical timescale, Paleoceanography, 11, 391-413, doi:10.1029/96PA02691.
42. Malaizé, B., C. Joly, M.-T. Vénec-Peyré, F. Bassinot, N. Caillon, and K. Charlier (2006), Phase lag between Intertropical Convergence Zone migration and subtropical monsoon onset over the northwestern Indian Ocean during marine isotopic substage 6.5 (MIS 6.5), Geochem. Geophys. Geosyst., 7, Q12N08, doi:10.1029/2006GC001353.
43. Martinson, D. G. (1987), Age dating and the orbital theory of the ice ages: Development of a high-resolution 0 to 300,000 year chronostratigraphy, Quat. Res. , 27, 1-29, doi:10.1016/0033-5894(87)90046-9.
44. Martrat, B., J. O. Grimalt, N. J. Shackleton, L. de Abreu, M. A. Hutterli, and T. F. Stocker (2007), Four climate cycles of recurring deep and surface water destabilizations on the Iberian Margin, Science, 317(5837), 502-507, doi:10.1126/science.1139994. (Pubitemid 47201823)
45. McManus, J. F., D. W. Oppo, and J. L. Cullen (1999), A 0.5-million-year record of millennialscale climate variability in the North Atlantic, Science, 283(5404), 971-975, doi:10.1126/science.283.5404.971. (Pubitemid 29100251)
46. Morley, J. J., and L. E. Heusser (1997), Role of orbital forcing in East Asian monsoon climates during the last 350 kyr: Evidence from terrestrial and marine climate proxies from core RC14-99, Paleoceanography, 12, 483-493, doi:10.1029/97PA00213.
47. Paillard, D., L. Labeyrie, and P. Yiou (1996), Macintosh program performs time-series analysis, Eos Trans. AGU, 77(39), 379, doi:10.1029/96EO00259.
48. Peltier, W. R. (2004), Global glacial isostasy and the surface of the ice-age Earth: The ICE-5G (VM2) model and GRACE, Annu. Rev. Earth Planet. Sci., 32, 111-149, doi:10.1146/annurev. earth.32.082503.144359.
49. Petoukhov, V., A. Ganopolski, V. Brovkin, M. Claussen, A. Eliseev, C. Kubatzki, and S. Rahmstorf (2000), CLIMBER-2: A climate system model of intermediate complexity. Part I-Model description and performance for present climate, Clim. Dyn., 16, 1-17, doi:10.1007/PL00007919.
50. Rahmstorf, S. (2002), Ocean circulation and climate during the past 120,000 years, Nature, 419, 207-214, doi:10.1038/nature01090. (Pubitemid 35033480)
51. Reichart,G. J., L. J. Lourens, andW. J. Zachariasse (1998), Temporal variability in the northern Arabian Sea oxygen minimum zone (OMZ) during the last 225,000 years, Paleoceanography, 13, 607-621, doi:10.1029/98PA02203.
52. Reichart, G.-J., H. Brinkhuis, F. Huiskamp, and W. J. Zachariasse (2004), Hyperstratification following glacial overturning events in the northern Arabian Sea, Paleoceanography, 19, PA2013, doi:10.1029/2003PA000900. (Pubitemid 39250688)
53. Richter, T. O., S. van der Gaast, B. Koster, A. Vaasrs, R. Gieles, H. C. de Stigter, H. de Haas, T. C. E. van Weering, and R. G. Rothwell (2006), The Avaatech XRF Core Scanner: Technical description and applications to NE Atlantic sediments, in New Techniques in Sediment Core Analysis, edited by R. G. Rothwell, Geol. Soc. Spec. Publ., 267, 39-50.
54. Rossignol-Strick, M. (1983), African monsoons, an immediate climatic response to orbital insolation, Nature, 304, 46-49, doi:10.1038/304046a0.
55. Ruddiman, W. F. (2006), What is the timing of orbital-scale monsoon changes?, Quat. Sci. Rev., 25, 657-658, doi:10.1016/j.quascirev. 2006.02.004.
56. Saher, M. H., F. Rostek, S. J. A. Jung, E. Bard, R. R. Schneider, M. Greaves, G. M. Ganssen, H. Elderfield, and D. Kroon (2009), Western Arabian Sea SST during the penultimate interglacial: A comparison of U37K′ and Mg/Ca paleothermometry, Paleoceanography, 24, PA2212, doi:10.1029/2007PA001557.
57. Schmiedl, G., and D. C. Leuschner (2005), Oxygenation changes in the deep western Arabian Sea during the last 190,000 years: Productivity versus deepwater circulation, Paleoceanography, 20, PA2008, doi:10.1029/2004PA001044. (Pubitemid 41410758)
58. Schmiedl, G., and A. Mackensen (2006), Multispecies stable isotopes of benthic foraminifers reveal past changes of organic matter decomposition and deepwater oxygenation in the Arabian Sea, Paleoceanography, 21, PA4213, doi:10.1029/2006PA001284. (Pubitemid 47272039)
59. Schmittner, A. (2005), Decline of the marine ecosystem caused by a reduction in the Atlantic overturning circulation, Nature, 434, 628-633, doi:10.1038/nature03476. (Pubitemid 40488552)
60. Schmittner, A., E. D. Galbraith, S. W. Hostetler, T. F. Pedersen, and R. Zhang (2007), Large fluctuations of dissolved oxygen in the Indian and Pacific oceans during Dansgaard-Oeschger oscillations caused by variations of North Atlantic Deep Water subduction, Paleoceanography, 22, PA3207, doi: 10.1029 /2006PA001384.
61. Schulz, H., R. von Rad, and H. Erlenkeuser (1998), Correlation between Arabian Sea and Greenland climate oscillations of the past 110,000 years, Nature, 393, 54-57.
62. Schulz, M., and M. Mudelsee (2002), REDFIT: Estimating red-noise spectra directly from unevenly spaced paleoclimatic time series, Comput. Geosci., 28(3), 421-426, doi:10.1016/S0098-3004(01)00044-9. (Pubitemid 34495196)
63. Skinner, L. C., and N. J. Shackleton (2005), An Atlantic lead over Pacific deep-water change across Termination I: Implications for the application of the marine isotope stage stratigraphy, Quat. Sci. Rev., 24, 571-580, doi:10.1016/j.quascirev.2004.11.008. (Pubitemid 40323481)
64. Spahni, R., et al. (2005), Atmospheric methane and nitrous oxide of the Late Pleistocene from Antarctic ice cores, Science, 310(5752), 1317-1321, doi:10.1126/science.1120132. (Pubitemid 41698861)
65. Spötl, C., A. Mangini, N. Frank, R. Eichstadter, and S. J. Burns (2002), Start of the last interglacial period at 135 ka: Evidence from a high Alpine speleothem, Geology, 30(9), 815-818, doi:10.1130/0091-7613(2002)0302.0. CO;2.
66. Stott, L., C. Poulsen, S. Lund, and R. Thunell (2002), Super ENSO and global climate oscillations at millennial time scales, Science, 297(5579), 222-226, doi:10.1126/science. 1071627.
67. Thompson, W. G., and S. L. Goldstein (2006), A radiometric calibration of the SPECMAP timescale, Quat. Sci. Rev., 25, 3207-3215, doi:10.1016/j.quascirev. 2006.02.007. (Pubitemid 46209376)
68. Tjallingii, R., M. Claussen, J.-B. Stuut, J. Fohlmeister, A. Jahn, T. Bickert, F. Lamy, and U. Rohl (2008), Coherent high- and lowlatitude control of the northwest African hydrological balance, Nat. Geosci., 1, 670-675, doi:10.1038/ngeo289.
69. Tuenter, E., S.L.Weber, F. J.Hilgen, L. J. Lourens, and A. Ganopolski (2005), Simulation of climate phase lags in response to precession and obliquity forcing and the role of vegetation, Clim. Dyn., 24, 279-295, doi:10.1007/s00382-004-0490-1. (Pubitemid 40473207)
70. Turney, C. S. M., A. P. Kershaw, S. C. Clemens, N. Branch, P. T. Moss, and L. K. Fifield (2004), Millennial and orbital variations of El Niño/Southern Oscillation and high-latitude climate in the last glacial period, Nature, 428, 306-310, doi:10.1038/nature02386. (Pubitemid 38418798)
71. van Aken, H. M., H. Ridderinkhof, and W. P. M. de Ruijter (2004), North Atlantic deep water in the south-western Indian Ocean, Deep Sea Res., Part I, 51(6), 755-776, doi:10.1016/j. dsr.2004.01.008.
72. Wang, P., S. Clemens, L. Beaufort, P. Braconnot, G. Ganssen, Z. Jian, P. Kershaw, and M. Sarnthein (2005), Evolution and variability of the Asian monsoon system: State of the art and outstanding issues, Quat. Sci. Rev., 24, 595-629, doi:10.1016/j.quascirev.2004. 10.002.
73. Wang, Y. J., H. Cheng, R. L. Edwards, Z. S. An, J. Y. Wu, C.-C. Shen, and J. A. Dorale (2001), A high-resolution absolute-dated Late Pleistocene monsoon record from Hulu Cave, China, Science, 294(5550), 2345-2348, doi:10.1126/science.1064618. (Pubitemid 33140556)
74. Wang, Y., et al. (2005), The Holocene Asian monsoon: Links to solar changes and North Atlantic climate, Science, 308(5723), 854-857, doi:10.1126/science.1106296. (Pubitemid 40629265)
75. Wang, Y., H. Cheng, R. L. Edwards, X. Kong, S. Xiaohua, S. Chen, J. Wu, X. Jiang, X. Wang, and A. Zhisheng (2008), Millennial- and orbital-scale changes in the East Asian monsoon over the past 224,000 years, Nature, 451, 1090-1093, doi:10.1038/nature06692. (Pubitemid 351317452)
76. Webster, P. J., V. O. Magaña, T. N. Palmer, J. Shukla, R. A. Tomas, M. Yanai, and T. Yasunari (1998), Monsoons: Processes, predictability, and the prospects for prediction, J. Geophys. Res., 103(C7), 14,451-14,510, doi:10.1029/97JC02719.
77. Winograd, I. J., T. B. Coplen, J. M. Landwehr, A. C. Riggs, K. R. Ludwig, B. J. Szabo, P. T. Kolesar, and K. M. Revesz (1992), Continuous 500,000-year climate record from vein calcite in Devils-Hole, Nevada, Science, 258(5080), 255-260, doi:10.1126/science. 258.5080.255.
78. You, Y. (1998), Intermediate water circulation and ventilation of the Indian Ocean derived from water-mass contributions, J. Mar. Res., 56, 1029-1067, doi:10.1357/002224098765173455.
79. Zahn, R., and T. F. Pedersen (1991), Late Pleistocene evolution of surface and mid-depth hydrography at the Oman Margin: Planktonic and benthic isotope records at Site 724, Proc. Ocean Drill. Program Sci. Results, 117, 291-308.
80. Ziegler, M., T. Jilbert,G. J. de Lange, L. J. Lourens, and G.-J. Reichart (2008), Bromine counts from XRF scanning as an estimate of the marine organic carbon content of sediment cores, Geochem. Geophys. Geosyst., 9, Q05009, doi:10.1029/2007GC001932.
81. Ziegler, M., E. Tuenter, and L. J. Lourens (2010a), The precession phase of the boreal summer monsoon as viewed from the eastern Mediterranean (ODP Site 968), Quat. Sci. Rev., 29, 1481-1490, doi:10.1016/j.quascirev. 2010.03.011.
82. Ziegler, M., L. J. Lourens, E. Tuenter, and G.-J. Reichart (2010b), High Arabian Sea productivity conditions during MIS 13-Odd monsoon event or intensified overturning circulation at the end of the mid-Pleistocene transition?, Clim. Past, 6, 63-76, doi:10.5194/cp-6-63-2010.