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Half-precessional dynamics of monsoon rainfall near the East African Equator

Abstract

External climate forcings—such as long-term changes in solar insolation—generate different climate responses in tropical and high latitude regions1. Documenting the spatial and temporal variability of past climates is therefore critical for understanding how such forcings are translated into regional climate variability. In contrast to the data-rich middle and high latitudes, high-quality climate-proxy records from equatorial regions are relatively few2,3,4, especially from regions experiencing the bimodal seasonal rainfall distribution associated with twice-annual passage of the Intertropical Convergence Zone. Here we present a continuous and well-resolved climate-proxy record of hydrological variability during the past 25,000 years from equatorial East Africa. Our results, based on complementary evidence from seismic-reflection stratigraphy and organic biomarker molecules in the sediment record of Lake Challa near Mount Kilimanjaro, reveal that monsoon rainfall in this region varied at half-precessional (11,500-year) intervals in phase with orbitally controlled insolation forcing. The southeasterly and northeasterly monsoons that advect moisture from the western Indian Ocean were strengthened in alternation when the inter-hemispheric insolation gradient was at a maximum; dry conditions prevailed when neither monsoon was intensified and modest local March or September insolation weakened the rain season that followed. On sub-millennial timescales, the temporal pattern of hydrological change on the East African Equator bears clear high-northern-latitude signatures, but on the orbital timescale it mainly responded to low-latitude insolation forcing. Predominance of low-latitude climate processes in this monsoon region can be attributed to the low-latitude position of its continental regions of surface air flow convergence, and its relative isolation from the Atlantic Ocean, where prominent meridional overturning circulation more tightly couples low-latitude climate regimes to high-latitude boundary conditions.

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Figure 1: Location and regional climate of the study site.
Figure 2: Lake Challa climate-proxy data in context.

References

  1. Clement, A. C., Hall, A. & Broccoli, A. J. The importance of precessional signals in the tropical climate. Clim. Dyn. 22, 327–341 (2004)

    Article  Google Scholar 

  2. Partin, J. W., Cobb, K. M., Adkins, J. F., Clark, B. & Fernandez, D. P. Millennial-scale trends in west Pacific warm pool hydrology since the Last Glacial Maximum. Nature 449, 452–455 (2007)

    Article  CAS  ADS  Google Scholar 

  3. Cruz, F. W. et al. Orbitally driven east-west antiphasing of South American precipitation. Nature Geosci. 2, 210–214 (2009)

    Article  CAS  ADS  Google Scholar 

  4. Gasse, F., Chalié, F., Vincens, A., Williams, M. A. J. & Williamson, D. Climatic patterns in equatorial and southern Africa from 30,000 to 10,000 years ago reconstructed from terrestrial and near-shore proxy data. Quat. Sci. Rev. 27, 2316–2340 (2008)

    Article  ADS  Google Scholar 

  5. Trauth, M. H., Maslin, M. A., Deino, A. & Strecker, M. R. Late Cenozoic moisture history of East Africa. Science 309, 2051–2053 (2005)

    Article  CAS  ADS  Google Scholar 

  6. Wang, Y. J. et al. Millennial- and orbital-scale changes in the East Asian monsoon over the past 224,000 years. Nature 451, 1090–1093 (2008)

    Article  CAS  ADS  Google Scholar 

  7. Fleitmann, D. et al. Holocene ITCZ and Indian monsoon dynamics recorded in stalagmites from Oman and Yemen (Socotra). Quat. Sci. Rev. 26, 170–188 (2007)

    Article  ADS  Google Scholar 

  8. Vellinga, M. & Wood, R. A. Global climatic impacts of a collapse of the Atlantic thermohaline circulation. Clim. Change 54, 251–267 (2002)

    Article  Google Scholar 

  9. McManus, J. F., Francois, R., Gherardi, J. M., Keigwin, L. D. & Brown-Leger, S. Collapse and rapid resumption of Atlantic meridional circulation linked to deglacial climate changes. Nature 428, 834–837 (2004)

    Article  CAS  ADS  Google Scholar 

  10. Zhang, R. & Delworth, T. L. Simulated tropical response to a substantial weakening of the Atlantic thermohaline circulation. J. Clim. 18, 1853–1860 (2005)

    Article  ADS  Google Scholar 

  11. deMenocal, P. et al. Abrupt onset and termination of the African Humid Period: rapid climate responses to gradual insolation forcing. Quat. Sci. Rev. 19, 347–361 (2000)

    Article  ADS  Google Scholar 

  12. Kutzbach, J. E. Monsoon climate of the early Holocene: climate experiment with Earth’s orbital parameters for 9000 years ago. Science 214, 59–61 (1981)

    Article  CAS  ADS  Google Scholar 

  13. Peterson, L. C., Haug, G. H., Hughen, K. A. & Röhl, U. Rapid changes in the hydrological cycle of the tropical Atlantic during the last glacial. Science 290, 1947–1950 (2000)

    Article  CAS  ADS  Google Scholar 

  14. Talbot, M. R., Filippi, M. L., Jensen, N. B. & Tiercelin, J.-J. An abrupt change in the African monsoon at the end of the Younger Dryas. Geochem. Geophys. Geosyst. 8 10.1029/2006GC001465 (2007)

  15. Thompson, L. G. et al. Kilimanjaro ice core records: evidence of Holocene climate change in tropical Africa. Science 298, 589–593 (2002)

    Article  CAS  ADS  Google Scholar 

  16. Tierney, J. E. et al. Northern Hemisphere controls on tropical Southeast African climate during the last 60,000 years. Science 322, 252–255 (2008)

    Article  CAS  ADS  Google Scholar 

  17. Cruz, F. W. et al. Insolation-driven changes in atmospheric circulation over the past 116,000 years in sub-tropical Brazil. Nature 434, 63–66 (2005)

    Article  CAS  ADS  Google Scholar 

  18. Haug, G. H., Hughen, K. A., Sigman, D. M., Peterson, L. C. & Rohl, U. Southward migration of the intertropical convergence zone through the Holocene. Science 293, 1304–1308 (2001)

    Article  CAS  ADS  Google Scholar 

  19. Thevenon, F., Williamson, D. & Taieb, M. A 22-kyr BP sedimentological record of Lake Rukwa (8° S, SW Tanzania): environmental, chronostratigraphic and climatic implications. Palaeogeogr. Palaeoclimatol. Palaeoecol. 187, 285–294 (2002)

    Article  Google Scholar 

  20. Berger, A., Loutre, M. F. & Mélice, J. L. Equatorial insolation: from precession harmonics to eccentricity frequencies. Clim. Past 2, 131–136 (2006)

    Article  Google Scholar 

  21. Peyron, O., Jolly, D., Bonnefille, R., Vincens, A. & Guiot, J. Climate of East Africa 6000 14C yr BP as inferred from pollen data. Quat. Res. 54, 90–101 (2000)

    Article  Google Scholar 

  22. Garcin, Y., Vincens, A., Williamson, D., Guiot, J. & Buchet, G. Wet phases in tropical southern Africa during the last glacial period. Geophys. Res. Lett. 33 L07703 10.1029/2005GL025531 (2006)

    Article  CAS  ADS  Google Scholar 

  23. Mumbi, C. T., Marchant, R., Hooghiemstra, H. & Wooller, M. J. Late Quaternary vegetation reconstruction from the Eastern Arc Mountains, Tanzania. Quat. Res. 69, 326–341 (2008)

    Article  Google Scholar 

  24. Barker, P. A. et al. A 14,000-year oxygen isotope record from diatom silica in two alpine lakes on Mt. Kenya. Science 292, 2307–2310 (2001)

    Article  CAS  ADS  Google Scholar 

  25. Verschuren, D. & Charman, D. J. in Natural Climate Variability and Global Warming (eds Battarbee, R. W. & Binney, H. E.) 189–231 (Wiley-Blackwell, 2008)

    Book  Google Scholar 

  26. Pinot, S. et al. Tropical paleoclimates at the Last Glacial Maximum: comparison of Paleoclimate Modeling Intercomparison Project (PMIP) simulations and paleodata. Clim. Dyn. 15, 857–874 (1999)

    Article  Google Scholar 

  27. Ruddiman, W. F. What is the timing of orbital-scale monsoon changes? Quat. Sci. Rev. 25, 657–658 (2006)

    Article  ADS  Google Scholar 

  28. EPICA community members One-to-one coupling of glacial climate variability in Greenland and Antarctica. Nature 444, 195–198 (2006)

    Article  ADS  Google Scholar 

  29. Rasmussen, S. O. et al. A new Greenland ice core chronology for the last glacial termination. J. Geophys. Res. 111 10.1029/2005JD006079 (2006)

  30. Berger, A. & Loutre, M.-F. Insolation values for the climate of the last 10 million years. Quat. Sci. Rev. 10, 297–317 (1991)

    Article  ADS  Google Scholar 

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Acknowledgements

This research was sponsored by funding agencies in Belgium (FWO-Vlaanderen), Denmark (Danish National Research Council), Germany (DFG) and The Netherlands (NWO) through the European Science Foundation (ESF) EuroCORES programme, EuroCLIMATE. Fieldwork was conducted with permission of the Kenyan Ministry of Education, Science and Technology (MOEST) and the Tanzania Commission for Science and Technology (COSTECH). We thank A. Alcantara, M. Kohler, S. Lauterbach, R. Niederreiter and S. Opitz for assistance with core collection and processing; D. Engstrom for 210Pb dating, A. Berger, D. Fleitmann, J. Kutzbach and Z. Liu for discussion, and E. Odada for support. J.M. acknowledges the support of the Institute for the Promotion of Innovation through Science and Technology in Flanders (IWT-Vlaanderen).

Author Contributions D.V. initiated and coordinated the research, and wrote the paper. J.S.S.D. was responsible for the production of the biomarker data, J.M. interpreted the seismic-reflection data, I.K. constructed the composite sediment sequence and depth scale, M.B. developed the sediment age model, and M.F. supervised core sampling and managed the project database. G.H.H. and all CHALLACEA members contributed their expertise to improving the discussed data sets and/or the manuscript.

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Correspondence to Dirk Verschuren.

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Verschuren, D., Sinninghe Damsté, J., Moernaut, J. et al. Half-precessional dynamics of monsoon rainfall near the East African Equator . Nature 462, 637–641 (2009). https://doi.org/10.1038/nature08520

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