The Thwaites Glacier in West Antarctica – a colossus the size of Florida – is in a phase of fast retreat. This is causing widespread concern about how much and how fast this so-called “Doomsday Glacier” may give up its ice to the ocean, triggering dangerous changes in sea-level. The potential impact of the Thwaites Glacier’s retreat is spine-chilling: a total loss of the glacier and surrounding icy basins could raise the sea level from three to ten feet.
In a new study led by the University of South Florida (USF), scientists mapped in high-resolution an important area of the seafloor in front of the glacier, providing a window into how fast Thwaites retreated in the past. By documenting over 160 parallel ridges which were created – like a footprint – as the glacier’s leading edge retreated, and analyzing the rib-like formations submerged 700 meters beneath the polar ocean, while factoring in the tidal cycle for the region, the experts were surprised to discover that the glacier had periods of extremely fast retreat in the past. For instance, at some point during the last two centuries, the glacier retreated at a rate of more than 2.1 kilometers per year – twice as fast as it did between 2011 and 2019.
“Our results suggest that pulses of very rapid retreat have occurred at Thwaites Glacier in the last two centuries, and possibly as recently as the mid-20th century,” said study lead author Alastair Graham, an associate professor of Geological Oceanography at USF.
“Thwaites is really holding on today by its fingernails, and we should expect to see big changes over small timescales in the future – even from one year to the next – once the glacier retreats beyond a shallow ridge in its bed,” added study co-author Robert Larter, a marine geophysicist at the British Antarctic Survey (BAS).
While previously, scientists thought that the Antarctic ice sheets are sluggish and rather slow to respond, these new findings show that the situation may be quite different and more worrisome. “Just a small kick to Thwaites could lead to a big response,” Professor Graham warned.
“This study is part of a cross-disciplinary collective effort to understand the Thwaites Glacier system better, and just because it’s out of sight, we can’t have Thwaites out of mind. This study is an important step forward in providing essential information to inform global planning efforts,” concluded Tom Frazer, dean of the USF College of Marine Science.
The study is published in the journal Nature Geoscience.
Image Credit: NASA/OIB/Jeremy Harbeck
By Andrei Ionescu, Earth.com Staff Writer