Southward movement of the Pacific intertropical convergence zone AD 1400–1850

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Tropical rainfall patterns control the subsistence lifestyle of more than one billion people. Seasonal changes in these rainfall patterns are associated with changes in the position of the intertropical convergence zone, which is characterized by deep convection causing heavy rainfall near 10 N in boreal summer and 3 N in boreal winter. Dynamic controls on the position of the intertropical convergence zone are debated, but palaeoclimatic evidence from continental Asia, Africa and the Americas suggests that it has shifted substantially during the past millennium, reaching its southernmost position some time during the Little Ice Age (AD 1400–1850). However, without records from the meteorological core of the intertropical convergence zone in the Pacific Ocean, quantitative constraints on its position are lacking. Here we report microbiological, molecular and hydrogen isotopic evidence from lake sediments in the Northern Line Islands, Galápagos and Palau indicating that the Pacific intertropical convergence zone was south of its modern position for most of the past millennium, by as much as 500 km during the Little Ice Age. A colder Northern Hemisphere at that time, possibly resulting from lower solar irradiance, may have driven the intertropical convergence zone south. We conclude that small changes in Earth’s radiation budget may profoundly affect tropical rainfall.

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Figure 1: Map of mean annual precipitation in the tropical Pacific with our sampling locations shown.
Figure 2: Sediment features from Washington Lake and Christmas Island lake F6.
Figure 3: Age–depth models for Washington Lake sediment.
Figure 4: Tropical Pacific precipitation proxy records during the past 1,200 years and selected records from the literature.


  1. 1

    Mann, M. E. et al. Proxy-based reconstructions of hemispheric and global surface temperature variations over the past two millennia. Proc. Natl Acad. Sci. USA 105, 13252–13257 (2008).

  2. 2

    Trenberth, K. E. et al. Progress during TOGA in understanding and modeling global teleconnections associated with tropical sea surface temperatures. J. Geophys. Res. 103, 14291–14324 (1998).

  3. 3

    Newton, A., Thunell, R. & Stott, L. Climate and hydrographic variability in the Indo-Pacific Warm Pool during the last millennium. Geophys. Res. Lett. 33, L19710 (2006).

  4. 4

    Langton, S. J. et al. 3,500 yr record of centennial-scale climate variability from the Western Pacific Warm Pool. Geology 36, 795–798 (2008).

  5. 5

    Verschuren, D., Laird, K. R. & Cumming, B. F. Rainfall and drought in equatorial east Africa during the past 1,100 years. Nature 403, 410–414 (2000).

  6. 6

    Anderson, D. M., Overpeck, J. T. & Gupta, A. K. Increase in the Asian southwest monsoon during the past four centuries. Science 297, 596–599 (2002).

  7. 7

    Alin, S. R. & Cohen, A. S. Lake-level history of Lake Tanganyika, East Africa, for the past 2,500 years based on ostracode-inferred water-depth reconstruction. Palaeogeogr. Palaeoclimatol. Palaeoecol. 199, 31–49 (2003).

  8. 8

    Brown, E. T. & Johnson, T. C. Coherence between tropical East African and South American records of the Little Ice Age. Geochem. Geophys. Geosys. 6, Q12005 (2005).

  9. 9

    Haug, G. H. et al. Southward migration of the intertropical convergence zone through the Holocene. Science 293, 1304–1308 (2001).

  10. 10

    Sifeddine, A. et al. Laminated sediments from the central Peruvian continental slope: A 500 year record of upwelling system productivity, terrestrial runoff and redox conditions. Prog. Oceanogr. 79, 190–197 (2008).

  11. 11

    Linsley, B. K., Dunbar, R. B., Wellington, G. M. & Mucciarone, D. A. A coral-based reconstruction of intertropical convergence zone variability over Central America since 1707. J. Geophys. Res. 99, 9977–9994 (1994).

  12. 12

    Hodell, D. A. et al. Climate change on the Yucatan Peninsula during the Little Ice Age. Quat. Res. 63, 109–121 (2005).

  13. 13

    Lund, D. C., Lynch-Stieglitz, J. & Curry, W. B. Gulf Stream density structure and transport during the past millennium. Nature 444, 601–604 (2006).

  14. 14

    Zhang, P. et al. A test of climate, sun, and culture relationships from an 1810-year Chinese cave record. Science 322, 940–942 (2008).

  15. 15

    Chiang, J. C. H., Zebiak, S. E. & Cane, M. A. Relative roles of elevated heating and surface temperature gradients in driving anomalous surface winds over tropical oceans. J. Atmos. Sci. 58, 1371–1394 (2001).

  16. 16

    Wester, L., Juvik, J. & Holthu, P. Vegetation history of Washington Island (Teraina), Northern Line Islands. Atoll Res. Bull. 358, 1–50 (1992).

  17. 17

    Saenger, C., Miller, M., Smittenberg, R. & Sachs, J. A physico-chemical survey of inland lakes and saline ponds: Christmas Island (Kiritimati) and Washington (Teraina) Islands, Republic of Kiribati. Sal. Syst. 2, 8 (2006).

  18. 18

    Bauld, J. Occurrence of benthic microbial mats in saline lakes. Hydrobiology 81–82, 87–111 (1981).

  19. 19

    Fenchel, T. Formation of laminated cyanobacterial mats in the absence of benthic fauna. Aquat. Microb. Ecol. 14, 235–240 (1998).

  20. 20

    Sachse, D. & Sachs, J. P. Inverse relationship between D/H fractionation in cyanobacterial lipids and salinity in Christmas Island saline ponds. Geochim. Cosmochim. Acta 72, 793–806 (2008).

  21. 21

    Gonfiantini, R. Handbook of Environmental Isotope Geochemistry (Elsevier, 1986).

  22. 22

    Garcia-Pichel, F., Nubel, U. & Muyzer, G.. The phylogeny of unicellular, extremely halotolerant cyanobacteria. Arch. Microbiol. 169, 469–482 (1998).

  23. 23

    Hamner, W. M. & Hamner, P. P. Stratified marine lakes of Palau (Western Caroline Islands). Phys. Geogr. 19, 175–220 (1998).

  24. 24

    Hamner, W. M., Gilmer, R. W. & Hamner, P. P. The physical, chemical, and biological characteristics of a stratified, saline, sulfide lake in Palau. Limnol. Oceanogr. 27, 896–909 (1982).

  25. 25

    Sessions, A. L., Burgoyne, T. W., Schimmelmann, A. & Hayes, J. M. Fractionation of hydrogen isotopes in lipid biosynthesis. Org. Geochem. 30, 1193–1200 (1999).

  26. 26

    Zhang, Z. & Sachs, J. P. Hydrogen isotope fractionation in freshwater algae: I. Variations among lipids and species. Org. Geochem. 38, 582–608 (2007).

  27. 27

    Volkman, J. K. et al. Microalgal biomarkers: A review of recent research developments. Org. Geochem. 29, 1163–1179 (1998).

  28. 28

    Gat, J. R. Oxygen and hydrogen isotopes in the hydrologic cycle. Annu. Rev. Earth Planet. Sci. 24, 225–262 (1996).

  29. 29

    Colinvaux, P. A. Climate and the Galápagos Islands. Nature 240, 17–20 (1972).

  30. 30

    Zhang, Z., Metzger, P. & Sachs, J. P. Biomarker evidence for the co-occurrence of three races (A, B and L) of Botryococcus braunii in El Junco Lake, Galápagos. Org. Geochem. 38, 1459–1478 (2007).

  31. 31

    Metzger, P., Berkaloff, C., Casadevall, E. & Coute, A. Alkadiene- and botryococcene-producing races of wild strains of Botryococcus braunii. Phytochemistry 24, 2305–2312 (1985).

  32. 32

    Moy, C. M., Seltzer, G. O., Rodbell, D. T. & Anderson, D. M. Variability of El Nino/Southern Oscillation activity at millennial timescales during the Holocene epoch. Nature 420, 162–165 (2002).

  33. 33

    Chiang, J. C. H., Cheng, W. & Bitz, C. M. Teleconnection mechanisms to the tropical Atlantic from an abrupt freshening of the North Atlantic Ocean. Geophys. Res. Lett. 35, L07704 (2008).

  34. 34

    Takahashi, K. & Battisti, D. S. Processes controlling the mean tropical Pacific precipitation pattern. Part I: The Andes and the eastern Pacific ITCZ. J. Clim. 20, 3434–3451 (2007).

  35. 35

    Chiang, J. C. H. & Bitz, C. M. Influence of high latitude ice cover on the marine Intertropical Convergence Zone. Clim. Dyn. 25, 477–496 (2005).

  36. 36

    Bard, E., Raisbeck, G., Yiou, F. & Jouzel, J. Solar irradiance during the last 1200 years based on cosmogenic nuclides. Tellus B 52, 985–992 (2000).

  37. 37

    Shindell, D. T., Schmidt, G. A., Miller, R. L. & Mann, M. E. Volcanic and solar forcing of climate change during the preindustrial era. J. Clim. 16, 4094–4107 (2003).

  38. 38

    Ramsey, C. B. Deposition models for chronological records. Quat. Sci. Rev. 27, 42–60 (2008).

  39. 39

    Druffel, E. R. M. Bomb radiocarbon in the Pacific: Annual and seasonal timescale variations. J. Mar. Res. 45, 667–698 (1987).

  40. 40

    Geitler, L. Rabenhorst’s Kryptogamenflora von Deutschland, Österreich und der Schweiz: 14 (1985 reprint: Königstein, Koletz Scientific Books) (Akademische, 1932).

  41. 41

    Komárek, J. & Anagnostidis, K. Süßwasserflora von Mitteleuropa (Gustav Fischer, 1999).

  42. 42

    Komárek, J. & Anagnostidis, K. Süßwasserflora von Mitteleuropa (Gustav Fischer, 2005).

  43. 43

    Smittenberg, R. H. & Sachs, J. P. Purification of dinosterol for hydrogen isotopic analysis using high-performance liquid chromatography–mass spectrometry. J. Chromatogr. A. 1169, 70–76 (2007).

  44. 44

    Wallace, J. M., Mitchell, T. P. & Lau, A. K.-H. Legates/MSU precipitation climatology, <> (1995).

  45. 45

    Jones, P. D. & Mann, M. E. Climate over past millennia. Rev. Geophys. 42, RG2002 (2004).

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Financial support was provided by the US National Science Foundation (J.P.S.), the US National Oceanic and Atmospheric Administration (J.P.S.), the Gary Comer Science and Education Foundation (J.P.S.) and the Alexander-von-Humboldt foundation through a Feodor-Lynen Research Fellowship (D.S.). Discussions with J. Chiang, K. Takahashi, A. Timmerman, M. Wallace, G. Philander, C. Wunsch, P. Colinvaux and C. Saenger improved this manuscript. M. Miller, C. Saenger, M. Dawson, L. Martin, P. Colin, L. Bell, The Coral Reef Research Foundation of Palau, J. Overpeck, J. Conroy, P. Colinvaux, M. Steinitz-Kannan, S. Fukada, K. Anderson, J. Briden and C. Corbett assisted with field work. O. Kawka, B. Demianew and R. Rottenfusser assisted in the laboratory. The Galápagos National Park, the Charles Darwin Foundation, the Republic of Kiribati and the Republic of Palau issued permits and provided assistance with field work.

Author information

J.P.S. conceived the research, acquired financial support, carried out field work and wrote the paper. D.S. contributed the Line Island data, aided by S.G., and assisted with writing. Z.Z. contributed the El Junco data and assisted with writing. R.H.S. carried out field work, contributed the Palau data and assisted with writing. D.S.B. assisted with writing.

Correspondence to Julian P. Sachs.

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