Haumoanamarch2005b credit alan blacklock niwa

Coastal erosion at Haumoana, Hawkes Bay. Photo: Alan Blacklock, NIWA

Case study: New Antarctic Ice Sheet data contributes to policy and planning

21 July 2023

The Antarctic Science Platform is generating improved, data-constrained models that are being used for planning and adaptation decision-making measures to manage the impacts of future sea level rise on Aotearoa and Antarctica.

Rising sea level is among the most visible effects of human-induced global warming. Since 1880, the global mean sea level has increased by 20cm, and since 1990 the rate of rise has increased up to six-fold.

Pinning down the rate of sea-level rise beyond 2050, and reducing the uncertainty, requires a focused effort from the scientific community to identify and understand the key rate-determining processes that affect melting of the Antarctic Ice Sheet (AIS) — the largest and most uncertain contributor to future sea level rise.

The ASP’s Antarctic Ice Dynamics Project has made major advances towards this goal:

  • Research is providing critical data for constraining assessments of the sensitivity and performance of the AIS models used in sea level projection.
  • We have identified and incorporated some of the key rate-determining processes into our ice sheet model. This model was used in the development of the IPCC’s Sixth Assessment Report, and is being used by the international community to understand the Antarctic contribution to global mean sea level.
  • ASP leads the international SWAIS2C Project (Sensitivity of the West Antarctic Ice Sheet (WAIS) under 2 degrees of global warming). This team will drill through the ice and underlying sediment at the grounding line of the WAIS - the most vulnerable part of the AIS. The focus of this coming Antarctic field season is to find out if it collapsed during the last time (125,000 years ago) the Earth experienced 1.5°C of global warming. At that time, global mean sea level was at least 5m higher.
  • The ASP has been working with Antarctic and New Zealand stakeholders to provide improved sea level projection information and tools.

The New Zealand Government’s National Adaptation Plan identified hazards related to sea level rise as one of the greatest set of risks facing Aotearoa, and a broad range of stakeholders are concerned with anticipating and managing the impacts of sea level change.

In collaboration with the NZ SeaRise Programme, the Platform has provided key data for a new national set of site-specific sea level projections, spaced every two kilometres around Aotearoa’s coastline. The data and the online tool are being used widely in co-designed case studies, and independently, by stakeholders including local councils, the insurance sector, national and regional emergency management agencies, Department of Conservation, infrastructure providers, and Iwi and Māori communities. Sea level projections are also included in the latest edition of the Ministry for the Environment’s Coastal Hazard’s Guidance to Local Government.

Map combo SLR

This map shows the bottom of the North Island, including the harbour coastline of Wellington city and a sea level rise projection for a location in Evans Bay, Wellington Harbour where the rate of local vertical land movement is 2.8 ± 0.9mm/year.

ASP research is also informing international policy development pathways. Antarctic ice sheet contribution to future sea level rise is a priority question in international climate change strategic plans (e.g. World Climate Research Programme, SCAR’s 2022 Antarctic Climate Change and Environment Decadal Synopsis, and SCAR’s research flagship INStabilities & Thresholds in ANTarctica (INSTANT).

In 2023, members of the Antarctic Ice Dynamics team delivered an Information Paper, co-sponsored by Scientific Committee for Antarctic Research (SCAR) and the Committee of Managers of National Antarctic Programs (COMNAP) to the 45th Antarctic Treaty Consultative Meeting on ‘Understanding Future Sea Level Change Around Antarctica’. The ASP will lead work with international partners to deliver a set of site-specific sea level projections for the coast of Antarctica.

Using these national and international pathways to policy impact, New Zealand’s Antarctic data and research is contributing to better decision making and advice that helps communities, planners, businesses and infrastructure providers to improve their resilience to the impacts of sea level rise.

This Case Study was prepared as part of the Platform’s annual reporting to MBIE for the 2022-2023 year. It illustrates how New Zealand’s Antarctic research on ice sheet dynamics is improving sea level rise projections, which in turn inform improved long-term policy and planning development in Aotearoa.

Contributors: Tim Naish