antarctic

Antarctic ice loss has tripled in a decade. If that continues, we are in serious trouble.

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antarcticIt is big news from the Antarctic and many media outlets have quite rightly picked it up and reported on this, so let’s dig into it a bit, by going to the alpha source.

Something dramatic is happening in the Antarctic. We have precise measurements going back to 1992 when satellites enabled us to measure what was going on in great detail. In essence …

  • From 1992 until 2012 Antarctica lost about 76 billion tons of ice each and every year
  • Since about 2012 that rate of ice loss has tripled to 219 billion tons per year.

To put all this another way and to translate it into something that directly impacts us, ice losses from Antarctica have increased global sea levels by 7.6 mm since 1992, with two fifths of this rise (3.0 mm) coming in the last five years alone. Prior to 2012, the Antarctic contributed 0.2mm per year to sea level rise.

But a few mm is tiny .. right?

Each and every year over decades it adds up, and that’s bad, especially if this process is accelerating. Antarctica stores enough frozen water to raise global sea level by 58 metres, and so knowing how much ice it is losing is key to understanding the impacts of climate change today and on into the future.

If this acceleration continues then costal communities and cities will have far less time that has been previously envisaged to cope with rising sea level.

If we hope to avert dire consequences then our window of opportunity to avoid the worst possible outcome has possible narrowed to as little as a decade.

The Alpha Source

The study that reports all this is titled “Mass balance of the Antarctic Ice Sheet from 1992 to 2017“. This is the source for the above numbers. The authors of this consist of a large group of climate scientists who are all Antarctic subject matter experts. They have collectively reviewed all the available measurements and so these are definitive figures. It it all part of the ice sheet mass balance inter-comparison exercise (IMBIE) that was established in 2011 as a community effort.

You can find their Press Release here.

Comments from the contributors to this study

Professor Shepherd from the University of Leeds who led this assessment …

We have long suspected that changes in Earth’s climate will affect the polar ice sheets. Thanks to the satellites our space agencies have launched, we can now track their ice losses and global sea level contribution with confidence.

According to our analysis, there has been a step increase in ice losses from Antarctica during the past decade, and the continent is causing sea levels to rise faster today than at any time in the past 25 years. This has to be a concern for the governments we trust to protect our coastal cities and communities.

Dr Ivins from NASA’s Jet Propulsion Laboratory in California …

The added duration of the observing period, the larger pool of participants, various refinements in our observing capability and an improved ability to assess both inherent and interpretive uncertainties, each contribute to making this the most robust study of ice mass balance of Antarctica to date.

Josef Aschbacher, ESA’s Director of Earth Observation Programmes …

CryoSatand Sentinel-1 are clearly making an essential contribution to understanding how ice sheets are responding to climate change and affecting sea level, which is a major concern.

While these impressive results demonstrate our commitment to climate research through efforts such as our Climate Change Initiative and scientific data exploitation activities, they also show what can be achieved by working with our NASA colleagues. Looking to the future, however, it is important that we have satellites to continue measuring Earth’s ice to maintain the ice-sheet climate data record.

Isabella Velicogna, professor of Earth system science, University of California, Irvine, and senior research scientist at NASA’s Jet Propulsion Laboratory …

Gravity measurements from the joint NASA and German Aerospace Center (DLR) GRACE mission help us track the loss of ice mass in the polar regions and impacts on sea level at points around the planet. The data from these spacecraft show us not only that a problem exists but that it is growing in severity with each passing year.”

Eric Rignot, professor of Earth system science, University of California, Irvine, andsenior research scientist at NASA’s Jet Propulsion Laboratory …

Measurements collected by radar satellites and Landsat over the years have documented glacier changes around Antarctica at an amazing level of precision, so that we have now a very detailed and thorough understanding of the rapid changes in ice flow taking place in Antarctica and how they raise sea level worldwide.

Benjamin Smith, senior principal investigator, University of Washington Applied Physics Lab …

We’re at a really exciting time in Antarctic glaciology, in that we have a lot of mature technologies for measuring ice-sheet changes that were not available when I started in the field in the early 2000s.

The IMBIE-2 work shows that these have come together just in time to let us watch some really important changes in the West Antarctic Ice Sheet and in the Peninsula. Over the next few years we’re going to see some more types of data, from ICESat-2, GRACE-FO, and NISAR, that should let us keep watching Antarctica change in even finer detail.

Dr Pippa Whitehouse, NERC Independent Research Fellow at Durham University…

Satellites have given us an amazing, continent-wide picture of how Antarctica is changing. The length of the satellite record now makes it possible for us to identify regions that have been undergoing sustained ice loss for over a decade.

The next piece of the puzzle is to understand the processes driving this change. To do this, we need to keep watching the ice sheet closely, but we also need to look back in time and try to understand how the ice sheet responded to past climate change.

Michiel van den Broeke, professor of polar meteorology at Utrecht University…

To enhance the interpretation of ice sheet mass changes as observed by satellites requires accurate modelling of the amount of snowfall on the ice sheet, something that cannot be reliably measured from space yet.

Our model results prove that mass loss from the Antarctic ice sheet is caused by acceleration of ice flow in West Antarctica and the Antarctic Peninsula, and that mass variations in East Antarctica are mainly driven by snowfall fluctuations.

Further Reading

The science writer Chris Mooney has also published details in the Washington Post …

Other tweets

Here are tweets that are pointing to other sources reporting on all of this …

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