A new study revealed that the Antarctic ice sheets retreated at an incredible speed of up to 50 meters per day. That retreat speed was confirmed to be faster than retreat rates from satellite observations.
The recent estimated retreat speed of Antarctic ice sheets was unveiled by researchers at the University of Cambridge, a research university in the UK. Their findings showed that the retreat speed of up to 50 meters per day was 10 times quicker than satellite-derived estimates. The culprit behind the retreat speed was the dual exposure to high temperature, in which warm air and water current melt away the sheet. They published the results in the journal Science.
What are Ice Sheets?
An ice sheet is a massive glacial land that extends over 50,000 square kilometers or 20,000 square miles. According to the National Snow and Ice Data Center, a US information center in polar and cryospheric research, there are two known present ice sheets on Earth: one that covers Greenland and the other that covers Antarctica. But in the last ice age, evidence suggested ice sheets that formerly covered a large area of North America and Scandinavia.
Estimates from scientific studies hint that the combined ice sheets in Antarctica and Greenland hold more than 99% of freshwater ice on the planet. If these ice sheets melt, that amount of freshwater will be released into the ocean, which will increase global sea levels exponentially. Many coastal areas will be wiped out by the rise in sea levels. The release of stored freshwater can also be problematic for territories that depend on ice sheets for irrigation.
The formation of ice sheets involves the snow from winter that does not melt during summer. Because summer did not affect the snow, it accumulated for hundreds of years and grew into large masses of ice, which created glaciers. Since ice sheets are white in color, they can easily reflect back sunlight, preventing them from melting. But ice sheets have no way to resist the effects of warm air and water currents. When parts of ice sheets are penetrated by warm air or water, the melting ice will show darker surfaces that help absorb sunlight. Thus, the blend of warm elements and sunlight can quickly melt ice sheets.
Aside from serving as reservoirs of freshwater for all living things, ice sheets have major influences on climate and weather. Massive high-altitude plateaus on ice caps can change the tracks of storms and create cold downslope winds. If ice sheets melt, their effects on the weather will be removed and nothing may be able to replace their function.
Based on details from Statista, a German portal for statistics, ice areas in Antarctica and the Arctic were detected with significant changes. In 2018, the overall change in the Antarctica sea ice area was 6.2% compared to 1980. That represented a total of 6.2% of shrinkage, from 18.8 million square kilometers in 1980 to 17.6 million square kilometers. In the Arctic in the same period, the melting was unbelievable at 38.8%. The total sea ice area in the region shrunk from 7.6 million square kilometers to 4.6 square kilometers.
Antarctic Ice Sheet Retreating Incredibly Fast
At the University of Cambridge, researchers discovered that the ice sheets of Antarctica were retreating significantly faster, compared to satellite data. Despite advancements in satellite imagery, calculations of retreat speed were unable to record the quickening glacial retreat of the ice sheets. But the autonomous underwater vehicle (AUV) deployed in the region was able to calculate ice conditions, as accurate as possible, which revealed a stunning insight: a retreat speed of up to 50 meters a day. That could reflect a retreat speed of 350 meters per week or 1,500 meters every 30 days, about 1.5 kilometers monthly.
"By examining the past footprint of the ice sheet and looking at sets of ridges on the seafloor, we were able to obtain new evidence on maximum past ice retreat rates, which are very much faster than those observed in even the most sensitive parts of Antarctica today," said Professor Julian Dowdeswell, lead author of the study and director of the Scott Polar Research Institute at Cambridge.
In the study, researchers took part in the Weddell Sea Expedition that happened in early 2019. During the study, the team could not acquire imagery of the legendary shipwreck Endurance. But they were able to carry out their scientific research, which included the mapping of the seafloor near the Larsen Ice shelf, east of the Antarctic Peninsula. Several methods were used to obtain data in the area, such as multiple AUVs, drones, and satellite observations. The data was used to compare the present and past form and flow of the ice shelves.
In general, data showed that ice shelves in some parts of Antarctica were weakening and might fail to support the inland. The weakening was correlated to the warm water currents hitting the thick ice from below. But what made the situation worse was the summer air temperatures: warm enough to melt the thick ice from above. The dual exposure from warm elements crippled the ice shelves and caused the glaciers they were protecting to flow rapidly to the sea. The double bombardment from warm air and water also induced their margins to retreat at a concerning speed.
With AUVs deployed, researchers managed to collect data on the historic ice shelf fluctuations from the geological reference of the Antarctic continental shelf. A series of delicate wave-like ridges on the seafloor was detected. Each of those ridges was approximately one meter in height and 20 to 25 meters apart. The series was dated about 12,000 years ago. The ridges were interpreted as the result of the collapsed grounding line – the zone where the immobile ice sheet starts to float as an ice shelf.
Their successful analyses of the data unveiled that the ice sheet was retreating from 40 to 50 meters per day. Within a year, the retreat speed would be at least 18 kilometers. From the satellite perspective, recent images determined a slower retreat speed. One instance was the observations in the Pine Island Bay, a melting glacier in Antarctica, which was found with an annual retreat speed of only 1.6 kilometers.
The bone-chilling environment of Antarctica and the Arctic is critical to the survival of penguins, polar bears, and other cold-bound animals. This is because the cold temperatures allow their prey to thrive normally. But without ice sheets, their prey die off and cold-bound animals would be forced to move to warmer areas.