An urgent priority for scientists is estimating the rate at which the Antarctic ice sheet will melt over the coming decades and centuries. 

A diagram

Despite our ever-improving understanding of ice sheet dynamics, difficulties associated with modelling polar ice sheet response to climate change remains the largest source of uncertainty in global sea level projections. This is especially true when modelling the Antarctic Ice Sheet. 

One of the primary objectives of the NZ SeaRise Programme and the related Antarctic Ice Dynamics Project in the Antarctic Science Platform, is to generate new constraints on ice sheet behaviour from historical records. These constraints are used to test and improve ice flow models that are commonly used to predict how the Greenland and Antarctic ice sheets change as air and ocean temperatures increase. 

In contrast to Greenland, ice loss from the Antarctic Ice Sheet is more difficult to predict. In West Antarctica, warm ocean currents erode and thin the bottom of large floating ice shelves, causing accelerating loss of the highly vulnerable West Antarctic Ice Sheet which largely sits below sea-level; while the vast East Antarctic ice sheet may gain mass, as warmer temperatures cause increased snowfall. This results in a greater range of future possibilities, from ice sheet growth that decreases sea level by 7.8 cm to ice sheet melt that increases sea level by 30 cm by 2100. 

The main cause of the differences between the Antarctic Ice Sheet model projections is the extent to which they incorporate processes that control the rapid melting of ice shelves as well as rapid irreversible retreat into deep basins below sea-level. 

Many of the models underestimate modern melt rates at the base of ice shelves. Better understanding of ocean circulation underneath the ice shelves is therefore critical for improving these ice flow models. This is why the IPCC has a “low confidence” and “medium confidence” set of projections for the global sea-level rise. 

Resolving the future melting of the Antarctic ice sheet in process-based models is one of the biggest challenges being addressed by the international Antarctic and climate research community. Researchers from Aotearoa New Zealand are making a major contribution through the Antarctic Science Platform and the National Antarctic Modelling Hub.

 
Featured
Kiwis can now see how sea-level rise will affect them
sea-level rise, sea level, climate change, projections
Kiwis can now see how sea-level rise will affect them
sea-level rise, sea level, climate change, projections
sea-level rise, sea level, climate change, projections
Sea level is rising faster than we thought
Sea level is rising faster than we thought
On the precipice
On the precipice

We need to strive to understand as much as we can about the role Antarctica and its ice sheets will play in a warming world – because what happens in Antarctica will shape what happens everywhere on the planet. On the precipice details why action is needed.

New research on the implications of ice loss from Antarctica
New research on the implications of ice loss from Antarctica

An international team of scientists, including GNS ice sheet modeller Dan Lowry, has published a paper predicting that sea-level rise from melting polar ice could be halved this century if we meet the Paris Agreement target of limiting warming to 1.5°C.

Fig2_T-Naish-Large.png
Policy implications of Antarctic ice sheet melting and global sea-level research

In this article, for the Antarctic Science Platform, Richard Levy and Tim Naish discuss the connections between the melting of Antarctic ice-sheets and planning to sea-level rise in Aotearoa.