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Abrupt Climate Change

Abrupt Climate Change

The response of tropical vegetation around the Atlantic Ocean to abrupt climate change markedly differs from region to region. In South America drier vegetation occurs during Heinrich Stadials (HS) in the northern part, which is at present under the influence of the Intertropical Convergence Zone, while wetter vegetation extends in Northeast Brazil, which lies nowadays south of the influence of Intertropical Convergence Zone. In Africa, a change to drier vegetation is found mainly in West Africa north of the equator and in East Africa. The Younger Dryas (YD) exhibits a rather heterogenous vegetation response.

HS in tropical Africa

Long pollen records of tropical Africa with enough temporal resolution to record Heinrich Stadials — Figure 3 from Hessler et al. (2010) Summary diagrams showing biome changes for high to medium temporal resolution sites from tropical Africa. An additional indicator pollen taxon is shown for each site. Fractions are expressed as percentages (X-axes).

HS in tropical South America

Long pollen records of tropical South America with enough temporal resolution to record Heinrich Stadials — Figure 4 from Hessler et al. (2010) Summary diagrams showing biome changes for high to medium temporal resolution sites from tropical South America. An additional indicator pollen taxon is shown for each site. Fractions are expressed as percentages (X-axes).

Model-Data comparison

Millennial-scale changes in vegetation records from tropical Africa and South America during the last glacial

Hessler I, Dupont L, Bonnefille R, Behling H, González C, Helmens KF, Hooghiemstra H, Lebamba J, Ledru MP, Lézine AM, Maley J, Marret F, Vincens A
Quaternary Science Reviews 29 (2010) 2882-2899
doi:10.1016/j.quascirev.2009.11.029

Tropical vegetation response to Heinrich Event 1 as simulated withthe UVic ESCM and CCSM3

Handiani D, Paul A, Prange M, Merkel U, Dupont L, Zhang X
Climate of the Past 9 (2013) 1683-1696
doi:10.5194/cp-9-1683-2013

Tropical climate and vegetation changes during Heinrich Event 1: a model-data comparison

Handiani D, Paul A, Dupont L
Climate of the Past 8 (2012) 37-57
doi:10.5194/cp-8-37-2012

Biome distributions calculated from the simulations of two different climate models for the Last Glacial Maximum (LGM) and Heinrich Stadial 1 (HS1) are compared to the biome reconstructions based on pollen data (Hessler et al. 2010). A comparison for Heinrich Stadial 1 between the model output and the reconstruction for tropical sites shows the matches and mismatches between models and data.

Fig4 Handiani et al. (2013) — Figure 4 of Handiani et al. (2013). Sites of pollen records compiled by Hessler et al. (2010) for the Last Glacial Maximum (a) and Heinrich Stadial 1 (b). Biome reconstructions at each site are represented by the colors of the circles (see legend).

Comparison between modeled and reconstructed tropical vegetation in Africa and South America during Heinrich Stadial 1 — Figure 5 of Handiani et al. (2013). Biomes (see legend of previous figure) calculated from two different model simulations for LGM and HS1. a, LGM UVic; b, LGM CCSM3; c, HS1 UVic; d, HS1 CCSM3. Blue-ligned triangles indicate where the model outcome matches with the reconstruction; red-ligned triangles denote where modelled and reconstructed biomes differ. Anomalies between HS1 and LGM simulations of UVic ESCM (e) and CCSM3 (f). CCSM, Community Climate System Model of the National Center for Atmospheric Research (Boulder, USA); ESCM, Earth System Climate Model; HS1, Heinrich Stadial 1; LGM, Last Glacial Maximum; UVic, Earth system model of Victoria University of intermediate complexity.

YD and HS1 in East Africa

Northern Hemisphere control of deglacial vegetation changes in the Rufiji uplands (Tanzania)

Bouimetarhan I, Dupont L, Kuhlmann H, Pätzold J, Prange M, Schefuß E, Zonneveld K
Climate of the Past 11 (2015) 751-764
doi:10.5194/cp-11-751-2015

HS 1 in West Africa

Sahel megadrought during Heinrich Stadial 1: Evidence for a three-phase evolution of the low- and mid-level West African wind system

Bouimetarhan I, Prange M, Schefuß E, Dupont L, Lippold J, Mulitza S, Zonneveld K
Quaternary Science Reviews 58 (2012) 66-76
doi:10.1016/j.quascirev.2012.10.015

Low- to high- productivity pattern within Henrich Stadial 1: Inferences from dinoflagellate cyst records off Senegal

Bouimetarhan I, Groeneveld J, Dupont L, Zonneveld K
Global and Planetary Change 106 (2013) 64-76
doi:10.1016/j.gloplacha.2013.03.007

HS around Cariaco Basin

As in West Africa the climate of the Heinrich Stadials in northern South America were dry.

Neotropical vegetation response to rapid climate changes during the last glacial period: Palynological evidence from the Cariaco Basin

González C, Dupont LM, Behling H, Wefer G
Quaternary Research 69 (2008) 217-230
doi:10.1016/j.yqres.2007.12.001

Reconstructing marine productivity of the Cariaco Basin during marine isotope stages 3 and 4 using organic-walled dinoflagellate cysts

González C, Dupont LM, Mertens K, Wefer G
Paleoceanography 23 (2008) PA3215
doi:10.1029/2008PA001602

YD & HS1 in Northeast Brazil

In contrast to northen South America or West Africa, the climate in Northeast Brazil was much wetter during the Younger Dryas and the Heinrich Stadials. The Intertropical Convergence Zone shifted southwards providing Northeast Brazil with rain.

Intermittent development of forest corridors in northeastern Brazil during the last deglaciation: Climatic and ecologic evidence

Bouimetarhan I, Chiessi CM, González-Arango C, Dupont L, Voigt I, Prange M, Zonneveld K
Quaternary Science Reviews 192 (2018) 86-96
doi:10.1016/j.quascirev.2018.05.026

Two-step vegetation response to enhanced precipitation in Northeast Brazil during Heinrich event 1

Dupont LM, Schlütz F, Teboh Ewah C, Jennerjahn TC, Paul A, Behling H
Global Change Biology 16 (2010) 1647-1660
doi: 10.1111/j.1365-2486.2009.02023.x

Accumulation rates of pollen en spores from sedimentents of GeoB3910 offshore Northeast Brazil — Fig. 6 of Dupont et al. (2010). Accumulation rates of pollen and spores against age. Inset in the curve on the right denotes accumulation rates of Cyatheaceae (tree ferns) spores. Far left, total pollen and spore counts on which the percentage calculation is based (not shown). At the right red bars denote calibrated radiocarbon ages.

The strong increase in the accumulation rates of pollen and spores is the combined result of higher pollen production by a more lush vegetation (forest) and increased run-off indicating increased precipitation during Heinrich Stadial 1. The icrease in tree fern spores during the upper part (Zone 3) indicates a second phase of Heinrich Stadial 1 being wetter than the first phase.

YD and HS in Angola and Namibia

The situation during the Younger Dryas and the Heinrich Stadials is again different in west southern Africa. Although the sea surface temperatures show a clear signature of these periods, the climate and vegetation on land do not seem to change accordingly.

Masked millennial-scale climate variations in southwest Africa during the last glaciation

Hessler I. Dupont L, Handiani D, Paul A, Merkel U, Wefer G
Climate of the Past, 8 (2012) 841-853
doi:10.5194/cp-8-841-2012

Impact of abrupt climate change in the tropical southeast Atlantic during Marine Isotope Stage 3

Hessler I, Steinke S, Groeneveld J, Dupont L, Wefer G
Paleoceanography 26 (2011) PA4209
doi:10.1029/2011PA002118

Land-sea linkages during deglaciation: High resolution records from the eastern Atlantic off the coast of Namibia and Angola (ODP Site 1078)

Dupont LM, Behling H
Quaternary International 148 (2006) 19-28
doi:10.1016/j.quaint.2005.11.004

Southwest African climate independent of Atlantic sea surface temperatures during the Younger Dryas

Dupont LM, Kim JH, Schneider RR, Shi N
Quaternary Research 61 (2004) 318-324
doi:10.1016/j.yqres.2004.02.005

Tribulus and Poaceae pollen percentages compared with alkenone sea surface temperatures offshore northern Namibia (GeoB1023) — Oxygen isotope records from the GIPS2 (bottom) and Byrd (top) ice cores (Johnsen et al., 1972; Grootes et al., 1993; Meese et al., 1994; Blunier & Brook, 2001). Alkenone derived sea surface temperatures from GeoB 1023 (note the sharp decline in SSTs to modern values in the past 1000 yr). Percentage grass and Tribulus pollen of the total pollen from GeoB 1023. YD, Younger Dryas; ACR, Anarctic Cold Reversal; HE1, Heinrich Event 1. Parallelism between grass pollen percentages and SSTs is only found for the period before 13,000 yr. NB: time scale runs from right (old) to left (young).

Correlation between vegetation in Southwestern Africa and oceanic upwelling in the past 21,000 years

Shi N, Dupont LM, Beug HJ, Schneider R
Quaternary Research 54 (2000) 72-80
doi:10.1006/qres.2000.2145

Sea level change

The timing of sea level changes during the Heinrich Stadials can be estimated through the registration of the vegetation succession around the Cariaco Basin in northern South America. The saltmashes make way for reedlands when sea level rizes. The reedlands, in turn, change to sedge swamps when sea level falls again.

Tropical salt marsh succession as sea-level indicator during Heinrich events

González C, Dupont L
Quaternary Science Reviews 28 (2009) 939-946
doi:10.1016/j.quascirev.2008.12.023

High resolution pollen record of shifting coastal vegetation dring sea level rise in the Cariaco Basin — Figure 3 from González & Dupont (2009). Comparison of the high-resolution palynological record from core MD03-2622 (Cariaco Basin) and sea-level reconstructions from the Red Sea during Heinrich Stadial 4. From top to bottom: reflectance data from core MD03-2622 (Laj, 2004); sea-level data from the central Red Sea (dark blue line after Sidall et al. 2003) and from the northern Red Sea (light blue line after Arz et al. 2007). Pollen percentages of Chenopodiaceae, Poaceae, and Cyperaceae indicate vegetation succession related to sea level. 1, Saltmarshes during sea-level rise (transgression); 3, Sedges during sea-level lowering (regression); 2, Reedlands in between. NB: time scale runs from right (old) to left (young).

Impacts of rapid sea level rise on mangrove deposit erosion: Application of taraxerol and Rhizophora records

Kim JH, Dupont LM, Behling H, Versteegh GJM
Journal Quaternary Science 20 (2005) 221-225
doi:10.1002/jqs.904

Taraxerol and Rhizophora pollen as proxies for tracking past Mangrove ecosystems

Versteegh GJM, Schefuß E, Dupont L, Marret F, Sinninghe Damsté J, Jansen F
Geochimica et Cosmochimica Acta 68 (2004) 411-422
doi:10.1016/S0016-7037(03)00456-3