Antarctica has lost 3 billion tons of ice since 1992 , and that ice loss has accelerated rapidly in the last five years, as highlighted by up to five studies published this week in the journal Nature Research.
In one of the most comprehensive studies to date on the continent’s frozen state, an international group of 84 researchers analyzed data from multiple satellite surveys, from 1992 to 2017.
They found that Antarctica is currently losing ice about three times faster than it did until 2012, reaching a rate of more than 241 billion tons (219 billion metric tons) per year. Total ice loss over the 25-year period contributed to sea level rise of approximately 8 millimeters and about 40%, that is, 3 mm, occurred in the last five years.
Millimeters of sea level rise may not sound like much, but previous studies suggested that the huge ice sheets of Antarctica weren’t going to be affected by climate change. Now, the new findings hint that the continent’s ice sheet may not be as resistant to warming as previously thought, and they present a very different picture of Antarctica’s possible contributions to a rising ocean.
Let’s keep this in mind: If all the ice in Antarctica were to melt, the resulting water could raise sea levels to levels of about 58 meters, according to the researchers.
Together, the published studies assess past and present conditions in Antarctica to determine the impact of climate change and human activity on the continent and present strategies for the future of its ecology and geology.
For the new study, the scientists combined data from three types of satellite measurements to track changes in the ice over time. Satellites that scanned Antarctic ice with altimeters gathered scientific evidence on its volume; another type of satellite measurement tracked the speed of glacial flow in the ocean; and a third type of observation calculated the gravity of the land masses around the planet, weighing the ice sheets in their entirety.
On their own, each of these techniques contained uncertainties; Factors such as varying snow on top of the ice or changes in rock could affect satellite measurements.
“Satellite measurements tell us that the ice sheet is much more dynamic than we used to think,” said Andrew Shepherd, a professor at the University of Leeds.
“If you take a look at the first assessment report of the IPCC (Intergovernmental Panel on Climate Change) 30 years ago, before we had satellite measurements of the polar regions, you will see that the ice sheets were not expected to respond to climate change. The general consensus in glaciology was that ice sheets couldn’t change rapidly, but that’s not the case, “Shepherd said.
The biggest change in annual ice loss was in West Antarctica, averaging around 58 billion tonnes in the years leading up to 2012, then skyrocketing to 175 billion tonnes per year in the five years after. Meanwhile, in the Antarctic Peninsula, the annual rate of ice loss increased from about 7 billion tonnes from 1992 to 2012 to 36 billion tonnes from 2012 to 2017, largely due to the collapse of the ice shelves.
Accelerated melting
Despite the fact that Antarctica is covered in ice throughout the year, its ice sheets recede and advance in annual cycles, a pattern that has persisted for thousands of years. But clues from the geological record suggest that the climate change driving ice loss in Antarctica is going much faster than during its periods of ice loss in the distant past.
Referencia: “Mass balance of the Antarctic Ice Sheet from 1992 to 2017”
https://www.nature.com/articles/s41586-018-0179-y / “Antarctic and global climate history viewed from ice cores”https://www.nature.com/articles/s41586-018-0179-y / “The global influence of localized dynamics in the Southern Ocean” https://www.nature.com/articles/s41586-018-0179-y / “Trends and connections across the Antarctic cryosphere” https://www.nature.com/articles/s41586-018-0179-y / “Choosing the future of Antarctica” https://www.nature.com/articles/s41586-018-0179-y
