Antarctic sea ice: Analysis

Targeted observation and process-informed modelling of Antarctic sea ice (TOPIMASI)

Antarctic sea ice plays a major role in the global climate system. Its presence maintains cold conditions that help sustain Antarctica’s ice sheets, and it affects the rate of global warming by changing heat uptake in the Southern Ocean. Antarctic sea ice has a significant influence on both the ocean and atmospheric components of the climate system, and sea ice extent is closely linked with weather systems over New Zealand.

This project builds on the work completed by the team in their Phase 1 Antarctic sea ice project.

While the rapid retreat of Arctic sea ice is alarming researchers worldwide, satellite observations show that, until 2016, sea ice extent had been increasing in the Antarctic. This behaviour is seemingly at odds with global warming. Since 2016 there has been a decrease in Antarctic sea ice – is this a reversal of the pattern, or natural variability?

Antarctic sea ice grows and recedes fastest at its margins. Ocean surface waves break up ice on the outer edges, while extremely cold water causes relatively thicker sea ice close to the continent. The first phase of this project involved field experiments on the inner and outer margins of Antarctic sea ice, including the first, fixed-wing aircraft, sea ice thickness survey in Antarctica. This showed surprisingly thick, freely moving, pack ice (more than 4m thick) in the SW Ross Sea. Waves in sea ice also behave in an unexpected way, forcing a revision of ice-ocean modelling.

We’re now focussed on completing our analysis, leading to a better understanding of Antarctic sea ice processes in the NZ Earth System Model (NZESM).