Antarctic ice loss – Expert Reaction

Antarctica has lost about 3 trillion tonnes of ice since 1992, which corresponds to a sea-level rise of around 8 millimetres.

An analysis published in Nature shows warm oceans have driven a tripling of ice-loss in Western Antarctica between 1992 and 2017. A collection of international researchers, known as the Ice sheet Mass Balance Inter-comparison Exercise (IMBIE) team, used 24 different satellite-based estimates to pull together this huge analysis on what impact warming is having on the coldest continent, and what we should do about it.

The SMC asked experts to comment on the research, which has been covered by national media, including NZ Herald, RNZ, and Stuff

Professor Tim Naish, Antarctic Research Centre, Victoria University of Wellington, comments:

“The perspective paper, Choosing the future of Antarctica, makes the point that human impacts on Antarctica and the Southern Ocean are well underway as a consequence of climate change, pollution of our oceans, resource extraction and tourism. It’s incorrect to think of Antarctica as this pristine unspoiled environment. Microplastics have made their way across the polar front and are now in the Southern Ocean. Tourism is having more and more impact as visitor numbers swell, two non-native invasive species of plant have colonised the warming Antarctic Peninsula, and warming oceans around the edge of the West Antarctic ice sheet are causing it to melt at an accelerating rate, contributing to rising sea-levels.

“The paper presents an assessment of two potential futures for Antarctica from the perspective of an observer 50 years in the future looking back. There is bad news and good news. The good news is that there is still time to prevent major meltdown of the ice sheets, and other far-reaching dangerous impacts, if nations collectively reduce their emissions in line with the Paris Climate Agreement target of 2C warming above pre-industrial levels. The bad news is that time is short and emissions need to peak in the next decade and reduce to zero before the end of the century. Urgent action is needed. Put simply if we cannot collectively tackle climate change, then it’s unlikely we will maintain Antarctica as a place for peace, nature and science.

“The authors of this paper have been recipients of the prestigious Tinker Muse Prize in Antarctic Science and Policy worth USD$100,000. Their expertise spans climate change, marine and terrestrial ecology, oceanography, glaciology, and the implications for policy.”

Conflict of interest statement: I am a contributor on the perspective paper Choosing the Future of Antarctica. 

Dr Craig Stevens, Principal Scientist, Marine Physics, NIWA and Associate Professor of Physics, University of Auckland, comments:

“This set of studies represents a landmark, both in terms of Antarctic, and climate, science. It brings together a huge team of researchers looking at one of the major challenges facing humanity – how much of the Antarctic ice sheet is melting and raising sea level.

“It makes use of a remarkable set of tools – mainly made possible by satellite observations over the past few decades. I think we sometimes take for granted the understanding made possible by these remarkable instruments orbiting the planet.

“The papers also makes clear how vital the role of the ocean, in particular the massive Antarctic Circumpolar Current, is in controlling present and future ice melting. In a similar vein to satellite science, the ever-increasing data set from ARGO, robotic ocean drifters, is dramatically changing what we know about the oceans.

“The combined studies give us a solid grounding in the wide range of impacts these changes will have, on a time frame that is in the lifetime of a significant portion of readers, and certainly in the lifetimes of their children and grandchildren. It lays out a clear pair of end-members based on how seriously we, as a species, take the impending impacts on our global climate system.

“Because the changes for our planet are unprecedented and wide-ranging, the 2070 narratives are especially useful and point to the stark differences in our near-future depending on how we address greenhouse gas emissions. I think the authors could have gone even further to consider the socio-economic impacts on coastal cities of this rising sea level.

“The synthesis also motivates where science needs to make more direct observations of ice and oceans. This study synthesis largely combines remotely sensed data and identifies hot-spots as well as areas and mechanics that are uncertain. Science at the poles is never cheap, but the importance of better understanding our future world means this investment is vital.”

No conflicts of interest.

Associate Professor Nick Golledge, Antarctic Research Centre, Victoria University of Wellington, and senior research fellow, GNS Science, comments:

“The new IMBIE study provides startling confirmation that the worlds largest ice sheet – and the largest potential contributor to sea level rise – is losing ice at an accelerating rate.”

What does this rising rate of ice loss tell us about global warming? 
“The acceleration in Antarctic ice sheet loss indicates not just that warmer ocean temperatures are melting the base of the ice shelves, but also that the grounded ice that feeds the ice shelves is thinning, accelerating, and retreating. These three signals are consistent with theoretical predictions of a ‘runaway retreat’ of the West Antarctic Ice Sheet, which may be irreversible over human timescales.”

What do we need to be doing more of? 
“As individuals, we need to acknowledge the impact that our lifestyle choices have on the environment. As a society we need to rapidly transition to a low-carbon footprint, and the easiest way to do that is to adopt an entirely plant-based diet.”

What needs to change in the short, medium and long-term?
“In the short term we need to stop pretending that this is someone else’s problem. We all need to take responsibility. Over the medium and long-term we need government policy to support the transition to an environmentally responsible and low-carbon economy, with commitments from all industry sectors to invest in ecologically sound practices.”

No conflicts of interest.

Professor Christina Hulbe, Dean of the School of Surveying, University of Otago, comments:

“The new collection of research and review papers paint a clear and coherent picture about the things that keep Antarctic scientists up at night.

“Antarctic glaciers and ice sheets are, collectively, losing mass at an increasing rate. Sea ice both causes and responds to changes in the atmosphere, ocean, and land-based ice and it’s changing in ways that are not completely understood. What happens in Antarctica does not stay there: ice cores reveal tight global connections as well as the unprecedented nature of the anthropogenic CO2 emission.

“We should prioritise monitoring in as many parts of the Antarctic and Southern Ocean system as we can, we should be multidisciplinary in our approach, and we should have a multi-decade to century scale plan.

“It’s clear that massive change is now underway in Antarctica and the Southern Ocean but I think it would be a mistake to read these new articles as all doom and gloom. While some amount of change is already locked in, there are always choices to be made and it’s still possible to avert the worst of the climate projections.

“Certainly, there is more we need to learn and the farther forward we go in time, the less certain the projections become. But I’ve never been at an Antarctic or climate conference where people said ‘that happened slower than I thought it would’. The system always seems to surprise us in the opposite direction. There is nothing here to be complacent about.”

No conflicts of interest.

Associate Professor Rob McKay, Antarctic Research Centre, Victoria University of Wellington comments:

“The latest mass balance findings indicate loss of the West Antarctic Ice Sheet is continuing to accelerate. While the 3mm of sea level rise seen over the past 5 years seems relatively small when taken at face value, it is the acceleration that is of greatest concern. This has the potential to continue accelerating, with geological evidence and computer models both indicating the rates of sea level rise relating to ice sheet melt can be more than ten times this rate in a warming climate.”

No conflicts declared.