A new study published in Nature, led by Monash University researcher Dr. Felicity McCormack of Securing Antarctica's Environmental Future (SAEF), examines how reliably scientists can predict future ice loss from Antarctica and how those predictions could improve sea level planning.

Antarctica's Potential Impact on Global Sea Levels

Reports from the Intergovernmental Panel on Climate Change (IPCC) indicate that global sea levels could rise by more than two meters by 2100 under high emission scenarios if large parts of the Antarctic Ice Sheet collapse.

An increase of that scale would put one quarter of Australian residential properties at risk of flooding. It could also make large areas of sovereign territory across the Pacific uninhabitable and force hundreds of millions of people worldwide to leave their homes. Such an outcome would rank among the largest humanitarian and economic crises in history.

Despite the scale of the threat, the path of sea level rise through 2100 remains highly uncertain. Much of that uncertainty comes from the difficulty of determining how quickly Antarctica will lose ice.

In a worst-case scenario, the IPCC has estimated that the rate of sea level rise caused by Antarctic ice loss alone could almost double over the next 30 years. Until now, however, researchers have lacked a strong estimate of how much Antarctica may contribute to rising seas during the next several decades, the period most relevant to government policy and coastal planning.

Testing How Far Ahead Ice Loss Can Be Predicted

The research focused on two central questions: how much ice Antarctica may lose over the next 30 to 50 years, and whether that loss can be predicted with enough confidence to give governments and nations time to prepare.

To address these questions, the team evaluated how predictable sea level rise was across a range of ice sheet model projections during this relatively near-term period.

According to Dr. McCormack, Antarctic ice loss remains strongly and consistently predictable until around the middle of the century. This means models may be able to provide dependable estimates of Antarctica's contribution to sea level rise during the decades most important for adaptation planning.

"If ice sheet models accurately reproduce the rates of ice loss we observe today, we can have confidence in using those same models to reliably predict Antarctica's contribution to sea level rise over the next 30 to 50 years. Accurately predicting how much and how fast global sea levels will rise offers vital information for future coastal planning and government policy," said Dr. McCormack.

Predictability Declines Later in the Century

That confidence weakens toward the end of the 21st century, when physical processes capable of rapidly increasing ice loss become more likely.

Some Antarctic ice rests on bedrock that lies below sea level. If this ice begins retreating quickly, the process can become difficult to stop or reverse. Once underway, it could produce far greater ice loss than near-term climate projections alone would suggest.

"The research findings provide a roadmap for future climate planning. By improving how ice sheet models represent critical physical processes that lead to rapid ice sheet retreat, we can narrow the deep uncertainty that hampers reliability of long-term sea level rise projections," Dr. McCormack said.

The findings suggest that a meaningful opportunity for climate action still exists. Over the next three decades, sea level rise pathways are relatively well constrained, making this period especially important for long-range adaptation and infrastructure planning.

A Critical Window for Climate Action

Professor Steven Chown, Director of SAEF, said the world should use this period of greater predictability to act and invest in stronger systems for monitoring Antarctica.

"The predictability identified in this research does not reduce long-term risk; instead, it provides a defined period in which to act with greater confidence. Improvements in observational systems and ice sheet model developments will directly translate into more reliable sea level projections for short-term planning horizons," Professor Chown said.

Professor Chown also said Australia is in a strong position to work with Indo-Pacific partners and help turn the findings into practical adaptation strategies.

"Pacific Island governments require reliable near-term projections to make decisions about infrastructure, community relocation, and long-term land use. Engagement on sea level science and adaptation planning represents a foreign policy opportunity and a regional responsibility," Professor Chown said.

Turning Ice Sheet Forecasts Into Policy

Dr. McCormack said it is essential to create a clear process for incorporating ice sheet model projections into policies addressing sea level rise.

"When models replicate present-day observations of Antarctic ice mass loss, their projected ice mass loss rates over the coming several decades provide a reliable foundation for planning and adaptation, while longer-term sea level rise uncertainties highlight the need for ongoing development," Dr. McCormack said.

The researchers argue that Antarctic forecasts may be most useful when presented across two distinct time periods: short-term ice loss that can be predicted with greater confidence, and longer-term change shaped by feedbacks that could rapidly accelerate retreat.

This two-stage approach could give policymakers a clearer basis for preparing for rising seas while also recognizing the much greater uncertainty that develops later in the century.

About Securing Antarctica's Environmental Future

Securing Antarctica's Environmental Future is a Monash-led research and workforce development program that forms a central part of the Australian Antarctic Program. SAEF conducts Antarctic and Southern Ocean research intended to support Australians, neighboring countries in the Asia-Pacific, and communities around the world as the climate continues to change.