Scientists say the next 30 to 50 years could be a key opportunity to predict Antarctic ice loss and prepare for the sea level rise it could cause.
New research published in natureSecuring the Future of the Antarctic Environment (SAEF), led by Monash University researcher Dr Felicity McCormack, is investigating how scientists can reliably predict future Antarctic ice loss and how these predictions can improve sea level planning.
Antarctica’s potential impact on global sea levels
A report from the Intergovernmental Panel on Climate Change (IPCC) shows that if large parts of the Antarctic ice sheet collapse, global sea levels could rise by more than two meters by 2100 under high emissions scenarios.
If this scale were to increase, a quarter of Australia’s residential areas would be at risk of flooding. Large areas of sovereign territory across the Pacific could also become uninhabitable, potentially forcing hundreds of millions of people around the world to flee their homes. Such an outcome would rank among the greatest humanitarian and economic crises in history.
Despite the scale of the threat, the path of sea level rise by 2100 remains highly uncertain. Much of that uncertainty stems from the difficulty of determining how quickly Antarctica is losing ice.
The IPCC estimates that in a worst-case scenario, the rate of sea level rise caused by Antarctic ice loss alone could nearly double over the next 30 years. But until now, researchers lacked strong estimates of how much Antarctica is likely to contribute to sea level rise in the coming decades, which is most relevant to government policy and coastal planning.
Test how far in advance you can predict ice loss
This study focused on two central questions. It’s about how much ice Antarctica could 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 researchers assessed how predictable sea level rise is across a range of ice sheet model projections over this relatively short period of time.
According to Dr McCormack, Antarctic ice loss is strongly and consistently predictable until about the middle of this century. This means the model may be able to provide reliable estimates of Antarctica’s contribution to sea level rise in the decades that are most important for adaptation planning.
Dr McCormack said: “If ice sheet models can accurately reproduce the currently observed rates of ice loss, we can be confident that the same models can reliably predict Antarctica’s contribution to sea level rise over the next 30 to 50 years. Accurately predicting the amount and rate of global sea level rise will provide important information for future coastal planning and government policy.”
Predictability will decline in the second half of this century
Towards the end of the 21st century, that confidence is weakening, and physical processes that could rapidly increase ice loss are likely to occur.
Some of Antarctica’s ice rests on rock below sea level. If this ice begins to rapidly retreat, it can be difficult to stop or reverse the process. Once underway, ice losses could be much greater than short-term climate projections alone suggest.
Dr McCormack said: “Our findings provide a roadmap for future climate planning. By improving how ice sheet models represent the key physical processes that lead to rapid ice sheet retreat, we can narrow the deep uncertainties that hamper the reliability of long-term sea level rise projections.”
The findings suggest that meaningful opportunities for climate action still exist. Sea level rise pathways will be relatively well contained over the next 30 years, making this period particularly important for long-term adaptation and infrastructure planning.
A critical moment for climate action
SAEF Director Professor Stephen Chown said the world should take advantage of this period of increased predictability to act and invest in stronger systems for Antarctic monitoring.
“The predictability revealed in this study does not reduce long-term risks, but rather provides a period of time in which we can act with more confidence. Improvements in observation systems and the development of ice sheet models will lead directly to more reliable sea level predictions in the short-term planning horizon,” Professor Chown said.
Professor Chown also said Australia was in a strong position to work with partners in the Indo-Pacific to translate research findings into practical adaptation strategies.
“Pacific Island governments need reliable short-term forecasts to make decisions about infrastructure, local population relocation, and long-term land use. Engagement in sea level science and adaptation planning is a foreign policy opportunity and a regional responsibility,” Professor Chown said.
Turning ice sheet prediction into policy
Dr McCormack said it was essential to create a clear process for incorporating ice sheet model predictions into policies to address sea level rise.
Dr McCormack said: “If the model reproduces current observations of Antarctic ice mass loss, the projected rate of ice mass loss over the coming decades provides a reliable basis for planning and adaptation, while the uncertainty of long-term sea level rise highlights the need for continued development.”
The researchers argue that forecasts for Antarctica may be most useful when presented over two different time periods: short-term ice loss, which can be more reliably predicted, and longer-term changes shaped by feedbacks that can rapidly accelerate retreat.
This two-tiered approach provides policymakers with a clearer basis for preparing for sea level rise while recognizing the much greater uncertainty that will emerge later this century.
On protecting Antarctica’s environmental future
Securing Antarctica’s Environmental Future is a Monash-led research and workforce development program that is at the heart of the Australian Antarctic Program. SAEF conducts research in Antarctica and the Southern Ocean with the aim of supporting Australians, our Asia-Pacific neighbors and communities around the world as the climate continues to change.
