Antarctic sea ice

small chunks of ice float just off the Antarctic coast

Targeted observation and process-informed modelling of Antarctic sea ice

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.

While the rapid retreat of Arctic sea ice is alarming researchers worldwide, satellite observations show that sea ice extent has actually been increasing in the Antarctic over the past 37 years. This behaviour is seemingly at odds with global warming. The truth is that current earth system models can’t faithfully reproduce the trends in sea ice coverage, and a lack of observations has meant that the drivers of these trends are poorly understood.

(In late 2016–early 2017, total Antarctic sea ice extent actually reduced. We still don’t know if this is a reversal of the pattern or just natural variability. Regardless, it’s important we understand what is going on.)

Antarctic sea ice grows and recedes fastest at the margins. The movement of the ocean surface waves break up ice on the outer edges, while extremely cold water causes sea ice to grow closer to the continent. This project involves field experiments on sea ice around Antarctica, and modelling work, to better understand the drivers of sea ice growth and decay. Our goal is to understand these processes well enough to ensure the NZ Earth System Model (NZESM) accurately reproduces the behaviour we’re seeing in Antarctic sea ice.

Project contact: Pat Langhorne, University of Otago
Project budget: $1.9 million
Project duration: 2015 – 2019

This project in the media:
University of Otago professor gets $1.9m for Antarctica research,
Beneath the Ross Ice Shelf, RadioNZ
Science on ice, Otago Daily Times
What lies beneath: Why NZ's slice of Antarctica is at the centre of an eco-mystery,
New Zealand's Next Top Model, New Zealand Geographic
Breaking the ice, NIWA

Research and findings:
Modelling wave-induced ice breakup in the marginal ice zone, Fabien Montiel & Vernon Squire, Proceedings of the Royal Society A
Time-dependent freshwater input from ice shelves: impacts on Antarctic sea ice and the Southern Ocean in an Earth System Model, Andrew G. Pauling et al. Geophysical Research Letters
Changes to sea ice thickness distribution due to Ice Shelf Water, Langhorne et al., Isaac Newton Institute for Mathematical Sciences


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