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Timothy Naish

Professor Timothy Naish FRSNZ. Photo: Supplied

2016: Professor Timothy Naish FRSNZ, Victoria University of Wellington, has been awarded a James Cook Research Fellowship in Physical Sciences for research entitled: 'The contribution of the Antarctic ice sheet to past and future sea-level rise and implications for New Zealand'

As a coastal nation the majority of New Zealand’s population live in cities and communities built around harbours and other low-lying locations. Consequently, sea-level rise presents a great risk for disruptive climate change to our economy, society and environment. The ability to accurately project future sea-level rises is difficult because of an incomplete understanding of important effects driving the rise. Currently, the single largest uncertainty hampering efforts to improve the predictions stems from a lack of knowledge concerning the potential contribution of the polar ice sheets, in particular the Antarctic ice sheet. This is further complicated by the realisation that the average temperature increase in the polar regions are higher than the average global temperature increase – a phenomenon termed ‘polar (temperature) amplification’ – due to a number of poorly understood amplifying feedbacks such as ocean heat uptake, ocean circulation, ozone hole recovery and more. The level of sea-level rise also depends on local factors. For example, some parts of New Zealand’s North Island are subsiding at up to 3mm per year due to plate tectonic processes. Vertical land movements, coastal morphology, sediment supply, wave and storm climate, ocean dynamics, and the regional geoidal deformation combine to affect the rate, magnitude and ultimately the impact of sea-level rise on a specific location.

In this project, Professor Naish will work toward reducing the uncertainty of future sea-level rise on two levels. Firstly, he will work closely with international collaborators to drill a geological record on the West Antarctic Ice Sheet that will help researchers to determine how the ice sheet has reacted to temperature changes in the past and hence provide more accurate predictions of future changes. Secondly, he will improve region-specific projections of sea-level rise in New Zealand by taking into account local influences and hydro-glacio-isostatic (GIA) modelling – the latter referring to the modelling of changes to Southern Ocean sea levels as a consequences of predicted rise of land masses previously depressed by the huge weight of ice sheets. Ultimately, better predictions of future sea-level rises are critically needed for anticipating and managing the socio-economic impacts of the sea-level rise in New Zealand.