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ANTARCTICA IN 2070: WHAT FUTURE WILL WE CHOOSE?
Choices made in the next decade will have long-term consequences for Antarctica and the globe, according to research published today in Nature.
The study explores how Antarctica and the Southern Ocean will change over the next 50 years, and how those changes will impact the rest of the globe.
Two scenarios are considered: one in which greenhouse gas emissions remain unchecked, and one in which strong action is taken to limit emissions and to manage increased human use of Antarctica.
In the high emissions narrative, by 2070 major ice shelves have collapsed, sea level rise has accelerated to rates not seen in 20,000 years, ocean acidification and over-fishing have altered Southern Ocean ecosystems, and failure to manage increased human pressures has degraded the Antarctic environment.
In the low emissions narrative, Antarctica in 2070 looks much like it does today.
The ice shelves remain intact, Antarctica makes a small contribution to sea level rise, and the continent remains a “natural reserve, dedicated to peace and science” as agreed by Antarctic nations in the late 20th century.
“Continued high greenhouse gas emissions risk committing us to changes in Antarctica that will have long-term and far-reaching consequences for Earth and humanity,” lead author and senior scientist with CSIRO’s Centre for Southern Hemisphere Oceans Research and the Antarctic Climate and Ecosystems Cooperative Research Centre in Hobart, Dr Steve Rintoul said.
“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, such as substantial sea level rise.”
The scenarios, based on the best available science, represent plausible futures rather than predictions.
The high emissions narrative assumes that little action was taken to respond to environmental and human pressures on Antarctica.
As a result, the Antarctic environment was hit by the combined effects of warming, ocean acidification, spread of invasive species and unrestricted growth in human activities, resulting in a degraded environment and altered ecosystems.
The low emissions narrative assumes that Antarctic nations worked together to establish policies to manage the environmental and social pressures on the continent.
Antarctic ecosystems remained largely unscathed, as warming and ocean acidification were kept in check, and growing human use of Antarctica for tourism, fisheries and bioprospecting was managed sustainably.
“The message from this work is clear,” co-author Professor Steven Chown of Monash University’s School of Biological Sciences and President of the Scientific Committee on Antarctic Research said.
“Global sustainability depends on a rapidly closing window of opportunity.
“If we take action now, to limit greenhouse gas emissions, Antarctic environments will remain much as we have come to know them over the past 200 years.
"If we do not, they will change dramatically, and through their connections to the rest of the Earth System, result in global impacts with irreversible consequences.”
The nine international authors, all winners of the prestigious Tinker-Muse Prize for Science and Policy in Antarctica, are experts in a range of disciplines, including biology, oceanography, glaciology, geophysics, climate science, and policy.
Expert Reaction
These comments have been collated by the Science Media Centre to provide a variety of expert perspectives on this issue. Feel free to use these quotes in your stories. Views expressed are the personal opinions of the experts named. They do not represent the views of the SMC or any other organisation unless specifically stated.
Professor Tim Naish, Antarctic Research Centre, Victoria University of Wellington, NZ
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.
Dr Steve Rintoul is a Physical Oceanographer from the Antartic Climate & Ecosystems CRC, CSIRO
This paper is important because it shows that Antarctica is losing ice, and raising sea level, at an accelerating rate. Over the 25 years of their analysis, loss of mass from West Antarctica has tripled. Even East Antarctica, once thought to be stable on long timescales, has shifted from mass gain to mass loss in recent years.
The research also confirms the important role of the ocean in controlling the fate of the Antarctic Ice Sheet. The largest mass loss is observed where relatively warm ocean waters are melting floating ice shelves from below. As the ice shelves thin and weaken, they provide less resistance to ice flow from the continent to the sea. This increases the rate of mass loss from the Antarctic Ice Sheet and therefore the rate of sea level rise.
A critical question for the future is how ocean-driven melting of Antarctic ice shelves will change as the earth warms. If more warm ocean waters reach Antarctica, this will further accelerate sea level rise.
Professor Helen Amanda Fricker is from the Scripps Institution of Oceanography and is currently on sabbatical at the Institute of Marine and Antarctic Studies (IMAS), as well as being a University of Tasmania almunus
On the 'Trends and connections across the cryosphere' paper:
"Antarctica's vast ice sheet 2,800km south of Australia stores enough water to raise global sea level by 55m. These studies confirm that it is losing more ice to the ocean as each year passes. The satellite record is now long enough that signatures are emerging of the atmospheric and oceanic processes that are causing it to change. Extending the satellite record further through continued monitoring will allow us to isolate those processes so that we can predict Antarctica's future behaviour and sea-level contribution."
On the Perspectives paper 'Future of Antarctica':
"The next few years will be a pivotal period for decision making with regard to Antarctica. As we observe the system for longer, we see more and more changes of the type we feared could happen as the climate warms. Depending on what is decided, we could be looking at significant and irreversible changes over the next 50 years.
Associate Professor Duanne White is from the Institute for Applied Ecology at the University of Canberra
Satellite records during the last few decades demonstrate that ice loss from Antarctica has accelerated, and now makes up a considerable contribution to rates of global sea level rise. This paper represents a thorough assessment of the current state of knowledge of Antarctic ice loss using three different methods that broadly agree on the same answer.
The results highlight that most of the ice loss to date has occurred in the warmer, more northerly parts of West Antarctica and the Antarctic Peninsula.
In the much larger ice mass in East Antarctica the story is a more varied. Here it is clear that some large coastal outlet glaciers are also losing mass and contributing to modern day sea level rise.
The satellite records also emphasise the value of recent on-ground work in the ‘Australian’ sector of East Antarctica supported by the Australian Antarctic Division. Here, myself and researchers from the University of Tasmania and Durham University have been working to help calibrate the satellite measurements.
By using GPS measurements and geologic records of ice sheet change we are helping to refine assessments of mass change in East Antarctica, and determine if the larger easterly part of the ice sheet is losing or gaining mass.
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