Nature article poses choices for the future of Antarctica

Choices made in the next decade will have long-term consequences for Antarctica and the globe, according to research published today in the journal Nature.

The authors, including Victoria University of Wellington’s Professor Tim Naish, are from the world’s leading Antarctic and climate change institutes and are experts in a range of disciplines, including biology, oceanography, glaciology, geophysics,

They say Antarctica and the Southern Ocean are closely coupled to the rest of the globe and so change in the region will have widespread consequences for the Earth and humanity.

The study, Choosing the future of Antarctica, contrasts two narratives on the future of Antarctica and the Southern Ocean, from the perspective of an observer in the year 2070 looking back on the past 50 years. Each narrative highlights the long-term ramifications of decisions made today.

In the first scenario, greenhouse gas emissions remain unchecked, the climate continues to warm, and little policy action is taken to respond to environmental and social factors affecting Antarctica.

In the second scenario, ambitious action is taken to limit greenhouse gas emissions and to establish policies that reduce anthropogenic pressure on the environment, slowing the rate of change in Antarctica.

These science-based scenarios represent plausible alternative futures rather than forecasts, the authors say.

“The trajectory that will play out over the next 50 years depends on choices made today,” said the paper’s lead author, Dr Steve Rintoul of the Centre for Southern Hemisphere Oceans Research and Antarctic Climate and Ecosystems Cooperative Research Centre in Hobart, Australia.

“Greenhouse gas emissions must start decreasing in the coming decade to have a realistic prospect of following the low emissions narrative and so avoid global impacts associated with change in Antarctica, such as substantial sea level rise,” he said.

Professor Naish says under the high emissions narrative, Antarctica and the Southern Ocean undergo widespread and rapid change, with global consequences.

“What these narratives show us is that reducing greenhouse gas emissions, in line with the Paris climate agreement, and implementing effective policy can still minimise change in the Antarctic environment and the rest of planet. Under the low emissions scenario in this paper, Antarctica looks much as it did in the earlier decades of the century and global sea-level rise remains under one metre,” he says.

In contrast, the global consequences set out under the high emissions narrative include dramatic loss of major ice shelves, sea warming, sea ice retreat and ocean acidification, and degradation of the environment caused by unrestricted growth in human use of Antarctica and introduced invasive pests.

"The approach of looking back is a creative way to communicate the immediacy of the problem. You can’t help but feel the necessity to act to ensure the right policy pathways are taken,” says Professor Craig Cary, Director of the New Zealand Antarctic Research Institute which helped fund the research.

Professor Naish and Associate Professor Nicholas Golledge from Victoria University of Wellington’s Antarctic Research Centre are also authors in a second paper published today in the same edition of Nature. It reveals that the East Antarctic Ice Sheet may eventually contribute to multi-metre global sea-level rise if action is not taken and greenhouse levels in the atmosphere continue to rise over coming decades.

Professor Naish, a geologist, uses past—or paleo—climate history to better understand future climate changes. His work with Associate Professor Golledge and their co-authors shows Earth last experienced the sort of climates that are predicted for the future, millions of years ago, before humans had evolved.

“If we don’t get on top of climate change and make good policy decisions now, we will end up with a world we haven’t seen for three million years, with a sea level up to 30 metres higher than now.”