Chapter 10 - Pleistocene Antarctic climate variability: ice sheet – ocean – climate interactions

• Main Authors: Wilson, D, van de Flierdt, T, McKay, RM, Naish, TR
• Other Authors: Florindo, F, Siegert, M, de Santis, L, Naish, T
• Format: Book Part
• Language: English
• Published: Elsevier 2022
• Subjects: Antarctic; Southern Ocean; The Antarctic; Antarc*; Antarctica; ice core; Ice Sheet; Sea ice
• Online Access: https://discovery.ucl.ac.uk/id/eprint/10113851/7/Wilson%20et%20al%202021%20ACE2%20Pleistocene%20chapter%20final%20Feb%202021.pdf; https://discovery.ucl.ac.uk/id/eprint/10113851/

During the Pleistocene, Earth experienced high-amplitude fluctuations in global temperature, atmospheric composition, ice sheet extent, and sea level that were forced by orbital variations in the seasonal distribution of solar energy across the planet. Subtle cyclical variations in forcing were greatly amplified by internal feedbacks in the Earth system, with processes in the polar regions influential for pole-to-equator temperature gradients and atmospheric carbon dioxide levels. Exploring the behaviour of the polar ice sheets and the Southern Ocean during this interval is crucial for understanding how the climate system operates and for constraining its sensitivity to future changes. Southern Ocean processes, including wind-driven upwelling, sea-ice formation, deep water production, and biological productivity, were instrumental in regulating Earth’s atmospheric carbon dioxide levels through Pleistocene glacial-interglacial cycles. On millennial timescales, rapid changes in ocean and atmospheric circulation were influenced by meltwater input from unstable ice sheet margins in both hemispheres, leading to highly variable regional and interhemispheric climate responses. This chapter provides an overview of the tools used in marine sediment and ice core archives to reconstruct Pleistocene changes in the Earth system. We discuss the mechanisms that controlled Earth’s climate over different timescales, and review the latest evidence that is revealing how the Antarctic Ice Sheet has both influenced and responded to Pleistocene climate change, including during intervals when Earth’s climate was similar to near-future projections. Despite experiencing ice volume changes that were modest in comparison to the advance and retreat of large Northern Hemisphere ice sheets, Antarctica has been a very active player in the ice sheet-ocean-climate system of the past 2.6 million years, and evidence increasingly suggests that it could respond dramatically to anthropogenic warming.