36 Improvements to our Understanding of Past Climate and Environments through the Development of Proxies, the Generation of New Biomarker Records, and the Interpretation of Sedimentary Archives

Tuesday, 19 March 2024
8:00 AM - 12:00 PM
Contoocook Room

EVALUATING CLIMATE VARIABILITY AND PALEOTEMPERATURE PROXIES IN TROPICAL EAST AFRICA DURING THE LATE PLEISTOCENE AND MIS 5E

Paper number: 36-3
Program: Theme Sessions
Time: 8:25 AM – 8:45 AM

Authors

Abstract

To better prepare for future climate change and anthropogenic global warming, we must understand the dominant forcings and feedbacks that naturally govern how globally-warm extremes affect terrestrial environments. These climatic controls are particularly difficult to resolve in tropical East Africa, as paleoclimate reconstructions spanning the Pleistocene and Holocene display spatially heterogeneous responses to varying climatological and oceanographic feedbacks. Here we present a multi-proxy climate reconstruction from the Lake Malawi drill core (MAL05-1), the longest (1.3 Ma) and most continuous high-resolution record of paleoclimatological data from terrestrial East Africa, spanning from 140,000 years ago (140 ka) to the present. We generate a new temperature record from Lake Malawi based on branched glycerol dialkyl glycerol tetraethers (GDGTs), membrane-spanning lipids that can be measured to reconstruct a variety of paleoenvironmental conditions, including temperature. A prior study at Malawi used branched GDGTs to reconstruct the regional climate response to global forcings from 140 to 600 ka, capturing large temperature variability corresponding with glacial/interglacial cycles. However, this record at Malawi has not yet captured the climatological context of Marine Isotope Stage 5e (MIS 5e, 130-100 ka), the penultimate interglacial. Our record from MIS 5e thus allows for a comparison of the relative magnitude of each glacial/interglacial period’s temperature change since 600 ka. MIS 5e has been identified as a super-interglacial of extreme global warmth relative to the pre-industrial present, and thus understanding this region’s response to anomalous global warmth offers critical insight into future climate change in East Africa. To our knowledge, this study presents the first continuous African continental temperature reconstruction spanning the entire interval that Homo sapiens have been present (~233 ka, Vidal et al., Nature, 2022), adding necessary climatological context to the emergence of early humans in East Africa. Our multi-proxy record spanning this interval furthermore highlights the efficacy of brGDGT-based tropical lacustrine paleotemperature calibrations at Malawi and contextualizes the evolution of regional climate systems into the present day.

Geological Society of America Abstracts with Programs. Vol. 56, No. 1

doi: 10.1130/abs/2024NE-397513

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