Landsat 8 image illustrating the highly vibrant SCAR Inlet Ice Shelf, Antarctic Peninsula, and sea ice production offshore. Credit: NASA/USGS, processed by Dr. Frazer Christie, Scott Polar Research Institute, University of Cambridge
Scientists discover that throughout periods of international warming, ice sheets can pull back at a rate of as much as 600 meters daily, which is 20 times quicker than the previous highest tape-recorded rate of retreat.
An international team of scientists, headed by Dr. Christine Batchelor from Newcastle University in the United Kingdom, used high-resolution imagery of the ocean floor to uncover the quick rate at which a previous ice sheet that extended from Norway declined at the end of the last Ice Age, around 20,000 years back.
The group, which also consisted of researchers from the universities of Cambridge and Loughborough in the UK and the Geological Survey of Norway, mapped more than 7,600 small landforms called corrugation ridges throughout the seafloor. The ridges are less than 2.5 m high and are spaced in between about 25 and 300 meters apart.
Example of corrugation ridges on the seafloor of mid-Norway. Two ridges were produced each day by the tidal-induced vertical movement of the retreating ice sheet margin. The scientists conclude that pulses of similarly fast retreat might soon be observed in parts of Antarctica. This consists of at West Antarcticas vast Thwaites Glacier, which is the topic of considerable global research study due to its prospective vulnerability to unstable retreat. The authors of this new research study suggest that Thwaites Glacier might undergo a pulse of quick retreat due to the fact that it has actually just recently retreated close to a flat area of its bed.
These landforms are understood to have formed when the ice sheets pulling away margin moved up and down with the tides, pushing seafloor sediments into a ridge every low tide. Provided that 2 ridges would have been produced every day (under 2 tidal cycles each day), the scientists had the ability to determine how rapidly the ice sheet retreated.
Example of corrugation ridges on the seafloor of mid-Norway. Two ridges were produced each day by the tidal-induced vertical movement of the retreating ice sheet margin.
Their results, reported in the journal Nature, reveal the former ice sheet underwent pulses of rapid retreat at a speed of 50 to 600 meters per day.
This is much faster than any ice sheet retreat rate that has been observed from satellites or presumed from comparable landforms in Antarctica.
” Our research offers a caution from the past about the speeds that ice sheets are physically capable of pulling away at,” said Dr. Batchelor. “Our outcomes show that pulses of fast retreat can be far quicker than anything weve seen up until now.”
Details about how ice sheets behaved during past durations of climate warming is crucial to inform computer system simulations that anticipate future ice sheet and sea-level change.
Sentinel-1 image composite illustrating the fast-flowing and highly fractured frontal margin of the Thwaites and Crosson ice shelves. Credit: Copernicus EU/ESA, processed by Dr. Frazer Christie, Scott Polar Research Institute, University of Cambridge
” This study shows the value of getting high-resolution images about the glaciated landscapes that are protected on the seafloor,” said research study co-author Dr. Dag Ottesen from the Geological Survey of Norway, who is included in the MAREANO seafloor mapping program that gathered the information.
The new research study recommends that periods of such fast ice-sheet retreat might only last for brief time periods (days to months).
” This demonstrates how rates of ice-sheet retreat balanced over a number of years or longer can conceal much shorter episodes of more rapid retreat,” said study co-author Professor Julian Dowdeswell of the Scott Polar Research Institute, University of Cambridge. “It is very important that computer simulations are able to reproduce this pulsed ice-sheet habits.”
The seafloor landforms also shed light into the system by which such fast retreat can take place. Dr. Batchelor and coworkers kept in mind that the previous ice sheet had actually retreated fastest throughout the flattest parts of its bed.
Landsat 8 image revealing the greatly crevassed front of Thwaites Glacier, West Antarctica, and icebergs and sea ice offshore. Credit: NASA/USGS, processed by Dr. Frazer Christie, Scott Polar Research Institute, University of Cambridge.
” An ice margin can unground from the seafloor and retreat near-instantly when it becomes resilient”, explained co-author Dr. Frazer Christie, also of the Scott Polar Research Institute. “This design of retreat only happens across reasonably flat beds, where less melting is required to thin the overlying ice to the point where it begins to float.”
The researchers conclude that pulses of likewise fast retreat might soon be observed in parts of Antarctica. This consists of at West Antarcticas vast Thwaites Glacier, which is the subject of significant global research due to its prospective vulnerability to unsteady retreat. The authors of this brand-new study recommend that Thwaites Glacier could go through a pulse of rapid retreat because it has recently pulled back close to a flat location of its bed.
” Our findings recommend that present-day rates of melting suffice to cause brief pulses of rapid retreat across flat-bedded locations of the Antarctic Ice Sheet, including at Thwaites”, said Dr. Batchelor. “Satellites may well detect this style of ice-sheet retreat in the future, particularly if we continue our existing pattern of climate warming.”
Recommendation: “Rapid, buoyancy-driven ice-sheet retreat of numerous metres daily” by Christine L. Batchelor, Frazer D. W. Christie, Dag Ottesen, Aleksandr Montelli, Jeffrey Evans, Evelyn K. Dowdeswell, Lilja R. Bjarnadóttir, and Julian A. Dowdeswell, 5 April 2023, Nature.DOI: 10.1038/ s41586-023-05876-1.
Other co-authors are Dr. Aleksandr Montelli and Evelyn Dowdeswell at the Scott Polar Research Institute of the University of Cambridge, Dr. Jeffrey Evans at Loughborough University, and Dr. Lilja Bjarnadóttir at the Geological Survey of Norway. The research study was supported by the Faculty of Humanities and Social Sciences at Newcastle University, Peterhouse College at the University of Cambridge, the Prince Albert II of Monaco Foundation, and the Geological Survey of Norway.
