Zarina Hewett

Zarina Hewett

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Zarina Hewett

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Start Year

2021 (Cohort 8)

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PhD Project
PhD Title

The AMOC and past abrupt climate change: new views on an old paradigm.

Research Theme

Earth, Atmosphere and Ocean Processes

Primary Supervisor
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Secondary Supervisor
Secondary Institution



The formation and circulation of deep waters in the North Atlantic is a critical component of the global climate system. Periods of abrupt climate change have occurred frequently during the Holocene (the last ~11,700 years), but the causal mechanisms and role of the North Atlantic preceding these events are not well understood. The aim of this project is to identify what changes, if any, occurred in the circulation and formation of deep waters before, during, and after key abrupt climate events throughout the Holocene (e.g., the 8.2ka, 4.2ka, and 2.7ka BP events). The project will utilise a wide range of palaeoceanographic proxies including analysis of stable isotopes and trace metals, sortable silt, radiocarbon ventilation age, and neodymium isotopic composition. These methods will enable the reconstruction of deep-water ventilation, flow speed, and the vertical distribution of deep watermasses. Current models struggle to reconstruct past climate variability, and the stability of the North Atlantic circulation remains somewhat uncertain. Constraining the behaviour of the North Atlantic during periods of abrupt climate is critical for constraining the mechanisms involved in abrupt climate change, improving climate model simulation of such events, and informing our understanding of the likelihood of similar abrupt events occurring in the future.

Policy Impact
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