New satellite research has confirmed that Antarctica’s ice is melting, but that it’s more complicated than simply shrinking glaciers. For years, scientists have been concerned about the impact of climate change on ice changes and how that impacts sea level contribution from the continent. However, the sheer scale of Antarctica has made measuring that problematic.
“Antarctica is way too big to survey from the ground,” Professor Andrew Shepherd, from the School of Earth and Environment at the University of Leeds, explains, “and we can only truly understand the trends in its ice cover by looking at the continent from space.” He and a team from Leeds, the University of California San Diego, and the University of Maryland have instead been looking to satellite measurements to get to grips with the changing topography.
That’s opened up decades-worth of data, and more than just how Antartica’s glaciers have changed in terms of their outline. The satellite’s observations have allowed the change of sea ice location, movement, and thickness to be tracked, for example. Changes in ice shelf thickness can also be followed.
The conclusions suggest it’s far more complicated – and potentially ominous – than blunter analysis of the impact of climate change might have had us believe. The total area of sea ice surrounding the continent has changed relatively little since satellite measurements first began, for example. However, ice shelf and sea ice thinning has led to a huge increase in water being added.
Warmer water has already melted ice shelves in West Antarctica, for instance; some are now as much as 18-percent thinner than they were in the early 1990s. Rising air temperatures at the Antarctic Peninsula, for example, have caused ice shelf collapse. Overall, more than 13,000 square miles of ice shelf area is believed to have been lost since the 1950s.
In turn, there’s a knock-on result for glacier changes. “Although breakup of the ice shelves does not contribute directly to sea-level rise – since ice shelves, like sea ice, are already floating – we now know that these breakups have implications for the inland ice,” Professor Helen Amanda Fricker, of the Scripps Institution of Oceanography at UC San Diego, says of the findings, “without the ice shelf to act as a natural buffer, glaciers can flow faster downstream and out to sea.”
It’s not a small change, either. Ice shelves have been thinning by up to 20 feet per year in the Amundsen Sea. That in turn has caused two glaciers to accelerate by 0.93 miles per year. Scientists estimate that together they could raise sea levels by over three feet.
The researchers are now looking to new satellites, including ICESat-2, to better track the changing Antarctic conditions. The full report has been published in Nature.