CPD Climate of the Past Discussions CPD 1814-9359 Copernicus GmbH Göttingen, Germany 10.5194/cpd-7-3511-2011 Masked millennial-scale climate variations in South West Africa during the last glaciation Hessler I. 1 Dupont L. 1 Handiani D. 1 Paul A. 1 Merkel U. 1 Wefer G. 1 MARUM – Center for Marine Environmental Sciences, University of Bremen, Bremen, Germany 20 10 2011 7 5 3511 3540 This is an open-access article ditributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. This article is available from http://www.clim-past-discuss.net/7/3511/2011/cpd-7-3511-2011.html The full text article is available as a PDF file from http://www.clim-past-discuss.net/7/3511/2011/cpd-7-3511-2011.pdf

Large and abrupt shifts between extreme climatic conditions characterise the last glacial and deglacial period and are thought to be transmitted by the atmospheric and oceanic circulation. Millennial-scale climatic shifts associated with North Atlantic Heinrich Stadials (HSs) are thought to be closely related to a reduction of the Atlantic Meridional Overturning Circulation (AMOC), which lead to the accumulation of heat in the South Atlantic and a southward shift of the Intertropical Convergence Zone (ITCZ). Due to the linkage between the oceans and the atmosphere it is assumed that HSs also influence the vegetation composition in the African tropics. To address the connection between tropical African vegetation development and high-latitude climate change we present a high-resolution marine pollen record from ODP Site 1078 (off Angola) covering the period 50–10 ka BP. Although several tropical African vegetation and climate reconstructions indicate an impact of HSs on the African subcontinent, our vegetation record shows no response. Model simulations conducted with an Earth System Model of Intermediate Complexity (EMIC) including a dynamical vegetation component lead to the hypothesis that the vegetation response during HSs might have been muted by mechanisms that partly cancel each other.

 References Alley, R. B., Clark, P. U., Keigwin, L. D., and Webb, R. S.: Making sense of millennial scale climate change, in: Mechanisms of Global Climate Change at Millennial Time Scales, edited by: Clark, P. U., Webb, R. S., and Keigwin, L. D., Geophysical Monograph, 112, American Geophysical Union, Washington, 385–394, 1999. Andersen, K. K., Svensson, A., Johnsen, S. J., Rasmussen, S. O., Bigler, M., Röthlisberger, R., Ruth, U., Siggaard-Andersen, M.-L., Peder Steffensen, J., Dahl-Jensen, D., Vinther, B. M., and Clausen, H. B.: The Greenland Ice Core Chronology 2005, 15–42 ka. Part 1: constructing the time scale, Quaternary Sci. Rev., 25, 3246–3257, 2006. Barker, S., Diz, P., Vautravers, M. J., Pike, J., Knorr, G., Hall, I. R., and Broecker, W. S.: Interhemispheric Atlantic seesaw response during the last deglaciation, Nature, 457, 1097–1102, 2009. Bonnefille, R. and Chalié, F.: Pollen-inferred precipitation time-series from equatorial mountains, Africa, the last 40 kyr BP, Global Planet. Change, 26, 25–50, 2000. Bonnefille, R. and Riollet, G.: Pollens des savanes d'Afrique orientale, CNRS Editions, Paris, 140~pp., 1980. Bonnefille, R. and Riollet, G.: The Kashiru pollen sequence (Burundi) palaeoclimatic implications for the last 40,000 yr B.P. in tropical Africa, Quaternary Res., 30, 19–35, 1988. Braconnot, P., Joussaume, S., de Noblet, N., and Ramstein, G.: Mid-Holocene and Last Glacial Maximum African monsoon changes as simulated within the Paleoclimate Modelling Intercomparison Project, Global Planet. Change, 26, 51–66, 2000. Broecker, W. S.: Massive iceberg discharges as triggers for global climate change, Nature, 372, 421–424, 1994. Broecker, W. S: Glacial Climate in the Tropics, Science, 272, 1902–1904, 1996. Broecker, W. S.: Paleocean circulation during the last deglaciation: A bipolar seesaw?, Paleoceanography, 13, 119–121, 1998. Butzin, M., Prange, M., and Lohmann, G.: Radiocarbon simulations for the glacial ocean: The effects of wind stress, Southern Ocean sea ice and Heinrich events, Earth Planet. Sci. Lett., 235, 45–61, 2005. Chapin, F. S., Schulze, E. D., and Mooney, H. A.: The ecology and economics of carbon storage in plants, Annu. Rev. Ecol. Syst., 21, 423–447, 1990. Collins, J. A., Schefusz, E., Heslop, D., Mulitza, S., Prange, M., Zabel, M., Tjallingii, R., Dokken, T. M., Huang, E., Mackensen, A., Schulz, M., Tian, J., Zarriess, M., and Wefer, G.: Interhemispheric symmetry of the tropical African rainbelt over the past 23,000 years, Nat. Geosci., 4, 42–45, 2010. Cowling, S. A. and Sykes, M. T.: Physiological Significance of Low Atmospheric CO<sub>2</sub> for Plant-Climate Interactions, Quaternary Res., 52, 237–242, 1999. Cox, P. M.: Description of the TRIFFID dynamic global vegetation model Hadley Center technical note, 24, 1–17, 2001. Cox, P. M., Betts, R. A., Bunton, C. B., Essery, R. L. H., Rowntree, P. R., and Smith, J.: The impact of new land surface physics on the GCM simulation of climate and climate sensitivity, Clim. Dynam., 15, 183–203, 1999. Dupont, L. M. and Agwu, C. O. C.: Environmental control of pollen grain distribution patterns in the Gulf of Guinea and offshore NW-Africa, Geol. Rundsch., 80, 567–589, 1991. Dupont, L. M. and Behling, H.: Land-sea linkages during deglaciation: High-resolution records from the eastern Atlantic off the coast of Nambia and Angola, Quaternary Int., 148, 19–28, 2006. Dupont, L. M. and Wyputta, U.: Reconstructing pathways of aeolian pollen transport to the marine sediments along the coastline of SW Africa, Quaternary Sci. Rev., 22, 157–174, 2003. Dupont, L. M., Behling, H., and Kim, J.-H.: Thirty thousand years of vegetation development and climate change in Angola (Ocean Drilling Program Site 1078), Clim. Past, 4, 107–124, http://dx.doi.org/10.5194/cp-4-107-2008doi:10.5194/cp-4-107-2008, 2008. Dupont, L. M., Schlütz, F., Teboh Ewah, C., Jennerjahn, T. C., Paul, A., and Behling, H.: Two-step vegetation response to enhanced precipitation in Northeast Brazil during Heinrich event 1., Global Change Biol., 16, 1647–1660, 2010. Ehleringer, J. R. and Monson, R. K.: Evolutionary and Ecological Aspects of Photosynthetic Pathway Variations, Annu. Rev. Ecol. Syst., 24, 411–439, 1993. EPICA Community Members: One-to-one coupling of glacial climate variability in Greenland and Antarctica, Nature, 444, 195–198, 2006. Faegri, K. and Iversen, J.: Textbook of pollen analysis IV Edition, edited by: Faegri, K., Kaland, P. E., Krzywinski, and Wiley, K. K., New York, 1989. Fairbanks, R. G., Mortlock, R. A., Chiu, T.-C., Cao, L., Kaplan, A., Guilderson, T. P., Fairbanks, T. W., and Bloom, A. L.: Marine Radiocarbon Calibration Curve Spanning 10,000 to 50,000 Years B.P. Based on Paired 230Th/234U/238U and 14C Dates on Pristine Corals, Quaternary Sci. Rev., 24, 1781–1796, 2005. Franke, J., Paul, A., and Schulz, M.: Modeling variations of marine reservoir ages during the last 45 000 years, Clim. Past, 4, 125–136, http://dx.doi.org/10.5194/cp-4-125-2008doi:10.5194/cp-4-125-2008, 2008. Gasse, F.: Hydrological changes in the African tropics since the Last Glacial Maximum, Quaternary Sci. Rev., 19, 189–211, 2000. Gasse, F., Chalié, F., Vincens, A., Williams, M. A. J., and 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, Quaternary Sci. Rev., 27, 2316–2340, 2008. González, C. and Dupont, L.: Tropical salt marsh succession as sea-level indicator during Heinrich events, Quaternary Sci. Rev., 28, 939–946, 2009. González, C., Dupont, L. M., Behling, H., and Wefer, G.: Neotropical vegetation response to rapid climate changes during the last glacial period: Palynological evidence from the Cariaco Basin, Quaternary Res., 69, 217–230, 2008. Handiani, D., Paul, A., and Dupont, L.: Tropical climate and vegetation changes during Heinrich Event 1: comparing climate model output to pollen-based vegetation reconstructions with emphasis on the region around the tropical Atlantic Ocean, Clim. Past Discuss., 7, 1973–2019, http://dx.doi.org/10.5194/cpd-7-1973-2011doi:10.5194/cpd-7-1973-2011, 2011. Harrison, S. P. and Prentice, C. I.: Climate and CO<sub>2</sub> controls on global vegetation distribution at the last glacial maximum: analysis based on palaeovegetation data, biome modeling and palaeoclimate simulations, Global Change Biol., 9, 983–1004, 2003. Heinrich, H.: Origin and consequences of cyclic ice rafting in the Northeast Atlantic Ocean during the past 130,000 years, Quaternary Res., 29, 142–152, 1988. Hessler, I., Dupont, L., Bonnefille, R., Behling, H., González, C., Helmens, K. F., Hooghiemstra, H., Lebamba, J., Ledru, M.-P., Lézine, A.-M., Maley, J., Marret, F., and Vincens, A.: Millennial-scale changes in vegetation records from tropical Africa and South America during the last glacial, Quaternary Sci. Rev., 29, 2882–2899, 2010. Hessler, I., Steinke, S., Groeneveld, J., Dupont, L., and Wefer, G.: Impact of abrupt climate change in the tropical southeast Atlantic during Marine Isotope Stage (MIS) 3., Paleoceanography, in press, 2011. Hostetler, S. W., Clark, P. U., Bartlein, P. J., Mix, A. C., and Pisias, N. J.: Atmospheric transmission of North Atlantic Heinrich events, J. Geophys. Res., 104, 3947–3952, 1999. Hughen, K. A., Baillie, M. G. L., Bard, E., Beck, J. W., Bertrand, C. J. H., Blackwell, P. G., Buck, C. E., Burr, G. S., Cutler, K. B., Damon, P. E., Edwards, R. L., Fairbanks, R. G., Friedrich, M., Guilderson, T. P., Kromer, B., McCormac, G., Manning, S., Bronk Ramsey, C., Reimer, P. J., Reimer, R. W., Remmele, S., Southon, J. R., Stuiver, M., Talamo, S., Taylor, F. W., van der Plicht, J., and Weyhenmeyer, C. E.: MARINE04 Marine Radiocarbon Age Calibration, 0-26 cal kyr BP, Radiocarbon, 46, 1059–1086, 2004. Janicot, S.: A comparison of Indian and African monsoon variability at different times scales, C. R. Geosci., 341, 575–590, 2009. Johnson, H. B., Polley, H. W., and Mayeux, H. S.: Increasing CO<sub>2</sub> and plant-plant interactions: effects on natural vegetation, Vegetatio, 104/105, 157–170, 1993. Kim, J.-H., Schneider, R. R., Müller, P. J., and Wefer, G.: Interhemispheric comparison of deglacial sea-surface temperature patterns in Atlantic eastern boundary currents, Earth Planet. Sci. Lett., 194, 383–393, 2002. Kim, J.-H., Schneider, R. R., Mulitza, S., and Müller, P. J.: Reconstruction of SE trade-wind intensity based on sea-surface temperature gradients in the Southeast Atlantic over the last 25 kyr, Geophys. Res. Lett., 30, 2144–2147, 2003. Lee, S.-Y., Chiang, J. C. H., Matsumoto, K., and Tokos, K. S.: Southern Ocean wind response to North Atlantic cooling and the rise in atmospheric CO<sub>2</sub>: Modeling perspective and paleoceanographic implications, Paleoceanography, 26, PA1214, http://dx.doi.org/10.1029/2010PA002004doi:10.1029/2010PA002004, 2011. Leroux, M.: Le climat de L'Afrique tropicale (Texte and atlas), Champion, Paris, France, 1983. Maley, J.: Contributions à l'étude du bassin tchadien. Atlas de pollens du Tchad, Bulletin du Jardin botanique national de Belgique, 40, 29–-48, 1970. Maley, J. and Brenac, P.: Vegetation dynamics, palaeoenvironments and climatic changes in the forests of western Cameroon during the last 28,000 years B.P, Rev. Palaeobot. Palyno., 99, 157–187, 1998. Merkel, U., Prange, M., and Schulz, M.: ENSO variability and teleconnections during glacial climates, Quaternary Sci. Rev., 29, 86–100, 2010. Mulitza, S., Prange, M., Stuut, J.-B., Zabel, M., von Dobeneck, T., Itambi, A.C., Nizou, J., Schulz, M., and Wefer, G.: Sahel megadroughts triggered by glacial slowdowns of Atlantic meridional overturning, Paleoceangraphy, 23, 1–11, 2008. Nicholson, S. E.: The nature of rainfall variability over Africa on time scales of decades to millenia, Global Planet. Change, 26, 137–158, 2000. Nicholson, S. E. and Entekhabi, D.: Rainfall Variability in Equatorial and Southern Africa: Relationships with Sea Surface Temperatures along the Southwestern Coast of Africa, J. Clim. Appl. Meteorol., 26, 561–578, 1987. Pearcy, R. W. and Eherlinger, J.: Comparative ecophysiology of C3 and C4 plants, Plant Cell Environ., 7, 1–13, 1984. Petit, J. R., Jouzel, J., Raynaud, D., Barkov, N. I., Barnola, J.-M., Basile, I., Bender, M., Chappellaz, J., Davis, M., Delaygue, G., Delmotte, M., Kotlyakov, V. M., Legrand, M., Lipenkov, V. Y., Lorius, C., Pépin, L., Ritz, C., Saltzman, E., and Stievenard, M.: Climate and atmospheric history of the past 420,000 years from the Vostok ice core, Antarctica, Nature, 399, 429–436, 1999. Polley, H. W., Johnson, H. B., and Mayeux, H. S.: Nitrogen and water requirements of C<sub>3</sub> plants grown at glacial to present carbon dioxide concentrations, Functional Ecology, 9, 86–96, 1995. Polley, H. W., Johnson, H. B., Mayeux, H. S., Brown, D. A., and White, J. W. C.: Leaf and plant water use effeciency of C<sub>4</sub> species grown at glacial to elevated CO<sub>2</sub> concentrations, Int. J. Plant Sci., 157, 164–170, 1996. Prentice, I. C. and Jolly, D.: BIOME 6000 participants, Mid-Holocene and glacial-maximum vegetation geography of the northern continents and Africa, J. Biogeogr., 27, 507–519, 2000. Revel, M., Ducassou, E., Grousset, F. E., Bernasconi, S. M., Migeon, S., Revillon, S., Mascle, J., Murat, A., Zaragosi, S., and Bosch, D.: 100, 000 Years of African monsoon variability recorded in sediments of the Nile margin, Quaternary Sci. Rev., 29, 1342–1362, 2010. Rühlemann, C., Mulitza, S., Lohmann, G., Paul, A., Prange, M., and Wefer, G.: Intermediate depth warming in the tropical Atlantic related to weakened thermohaline circulation: Combining paleoclimate and modeling results for the last deglaciation, Paleoceanography, 19, PA1025, http://dx.doi.org/10.1029/2003PA000948doi:10.1029/2003PA000948, 2004. Skinner, L. C.: Revisiting the absolute calibration of the Greenland ice-core age-scales*, Clim. Past, 4, 295–302, http://dx.doi.org/10.5194/cp-4-295-2008doi:10.5194/cp-4-295-2008, 2008. Sowunmi, M. A.: Pollen grains of Nigerian plants, Grana, 13, 145–186, 1973. Sowunmi, M. A.: Pollen of Nigerian plants 2. Woody species, Grana, 34, 39–44, 1995. Shannon, L. V. and Nelson, G.: The Benguela: Large Scale Features and Processes and System Variability, in: The South Atlantik: Present and Past Circulation, edited by: Wefer, G., Berger, W. H., Siedler, G. and Webb, D. J., Springer-Verlag Berlin Heidelberg, 163–210, 1996. Shannon, L. V., Agenbag, J. J., and Buys, M. E. L.: Large- and mesoscale features of the Angola-Benguela Front, S. Afr. J. Marine Sci., 5, 11–34, 1987. Shi, N., Dupont, L. M., Beug, H.-J., and Schneider, R.: Vegetation and climate changes during the last 21 000 years in S.W. Africa based on a marine pollen record, Veg. Hist. Archaeobot., 7, 127–140, 1998. Stockmarr, J.: Tablets with spores used in absolute pollen analysis, Pollen Spores, 13, 615–621, 1971. Stramma, L. and Peterson, R. G.: Geostrophic Transport in the Benguela Current Region, J. Phys. Oceanogr., 19, 1440–1448, 1989. Street-Perrott, F. A., Huang, Y., Perrott, R. A., Eglinton, G., Barker, P., Khelifa, L. B., Harkness, D. D., and Olago, D. O.: Impact of Lower Atmospheric Carbon Dioxid on Tropical Mountain Ecosystems, Science, 278, 1422–1426, 1997. Stuiver, M., Reimer, P. J., Bard, E., Beck, W., Burr, G. S., Hughen, K. A., Kromer, B., McCormac, G., van der Pflicht, J., and Spurk, M.: INTCAL98 radiocarbon age calibration, 24,000-0 cal BP, Radiocarbon, 40, 1041–1083, 1998. Sultan, B. and Janicot, S.: The West African Monsoon Dynamics. Part 2: The "Preonset" and "Onset" of the Summer Monsoon, J. Climate, 16, 3407–3427, 2003. Tierney, J. E., Russell, J. M., Huang, Y., Damste, J. S. S., Hopmans, E. C., and Cohen, A. S.: Northern Hemisphere Controls on Tropical Southeast African Climate During the Past 60,000 Years, Science, 322, 252–255, 2008. Tjallingii, R., Claussen, M., Stuut, J.-B. W., Fohlmeister, J., Jahn, A., Bickert, T., Lamy, F., and Röhl, U.: Coherent high- and low-latitude control of the northwest African hydrological balance, Nat. Geosci., 1, 670–675, 2008. Vellinga, M. and Wood, R. A.: Global Climatic Impacts of a Collapse of the Atlantic Thermohaline Circulation, Climatic Change, 54, 251–267, 2002. Vincens, A., Garcin, Y., and Buchet, G.: Influence of rainfall seasonality on African lowland vegetation during the late Quaternary: pollen evidence from Lake Masoko, Tanzania, J. Biogeogr., 24, 1274–1288, 2007. Ward, J. K., Tissue, D. T., Thomas, R. B., and Strain, B. R.: Comparative responses of model C3 and C4 plants to drought in low and elevated CO<sub>2</sub>, Global Change Biol., 5, 857–867, 1999. Weaver, A. J., Eby, M., Wiebe, E. C., Bitz, C. M., Duffy, P. B., Ewen, T. L., Fanning, A. F., Holland, M. M., MacFadyen, A., Matthews, H. D., Meissner, K. J., Saenko, O., Schmittner, A., Wang, H., and Yoshimori, M.: The UVic earth system climate model: Model description, climatology, and applications to past, present and future climates, Atmosphere-Ocean, 39, 361–428, 2001. Wefer, G., Berger, W. H., Richter, C., and Shipboard Scientific Party: Proceedings of the Ocean Drilling Program, Initial. Reports, 175, College Station, TX (Ocean Drilling Program), 1998. White, F.: The Vegetation of Africa. Natural Rescourses Research, UNESCO, 356~p., 353 mapsp, 1983. Wolff, E. W., Chappellaz, J., Blunier, T., Rasmussen, S. O., and Svensson, A.: Millennial-scale variability during the last glacial: the ice core record, Quaternary Sci. Rev., 29, 2828–2838, 2010. Ybert, J. P.: Altas des pollens de Côte d'Ivoire. ORSTOM, Paris, Initiations Documentation Technique, 40, 40~pp., 1979. Zhang, R. and Delworth, T. L.: Simulated tropical response to a substantial weakening of the Atlantic Thermohaline Circulation, J. Climate, 18, 1853–1860, 2005.