New Research Reveals Significant Thinning of Antarctica’s Ice Shelves
New research has indicated that more than 40 percent of Antarctica’s ice shelves have experienced significant thinning over the last 25 years. This worrying development could potentially speed up the rise of sea levels by allowing more land ice to flow into the ocean. The study, led by Benjamin Davison, was released on Thursday and provides further evidence of the impact of rising global temperatures on the continent.
Davison, who is a researcher at the University of Leeds, expressed his surprise at the extent of ice shelves that are deteriorating rapidly and continuously. He stated, “Lots of ice shelves, not just the big ones, are steadily losing mass over time with no sign of recovery.” Ice shelves are vast sections of ice that float on the ocean’s surface, originating from glaciers on land. They play a critical role in restricting the flow of land ice into the ocean. However, as they thin or retreat, the land ice can flow more rapidly, leading to an accelerated rise in sea levels. The melting of the Antarctic and Greenland ice sheets has contributed to more than one-third of total sea level rise in recent decades.
The study analyzed over 100,000 satellite images from 1997 to 2021 and found that 71 out of the 162 ice shelves surrounding Antarctica had reduced in volume. Nearly 50 ice shelves lost more than 30 percent of their initial mass during this period. While 29 shelves gained mass and 62 remained relatively unchanged, the overall trend of shrinking ice shelves is cause for concern.
Davison highlighted that healthy ice shelves naturally retreat and grow over time. They constantly flow and advance, losing mass through processes like melting or calving, which is when parts of the front break off into the ocean. However, the significant number of shrinking ice shelves observed in the study indicates an interruption in this natural cycle.
The most substantial decrease in ice shelves was observed on the western side of Antarctica, where warmer water erodes the shelves from beneath. The majority of ice shelves on the western side experienced ice loss. For example, the Getz Ice Shelf in West Antarctica lost 1.9 trillion tons of ice primarily due to melting at its base, while the Pine Island Ice Shelf lost 1.3 trillion tons, with a third attributed to calving.
In contrast, most ice shelves in East Antarctica either increased in volume or remained stable. Davison explained that the east is less exposed to warm water compared to the other side of the continent. A band of cold water along the coast acts as a protective barrier against warmer water intrusion. However, pockets of shrinking ice shelves were still observed in this region, and researchers are investigating the possible reasons.
The study also highlighted an alarming collapse of the Conger Ice Shelf in East Antarctica in March 2022. Within a few weeks, this ice shelf, about the size of New York City, completely disintegrated, likely triggered by an unprecedented heat wave in Antarctica.
The thinning of ice shelves has had noticeable effects on the surrounding environment. Over the 25-year study period, an estimated 66.9 trillion tons of fresh water from the ice shelves entered the ocean. This influx of fresh water can dilute the saltier ocean water, making it lighter and weakening ocean circulation. Scientists have already observed changes in ocean circulation around Antarctica due to this phenomenon.
Ice scientist Alex Gardner, who was not involved in the research, observed that the study’s results confirm previous work on ice shelf changes, including his own findings. Gardner emphasized that when considering the entirety of Antarctic ice shelves, a clear pattern of retreat and thinning is visible – a trend expected in a warming world.
While the current data set is not long enough to definitively establish a direct link between these changes and climate change, Davison believes it would be a “remarkable coincidence” if the natural variability of ice shelves alone were responsible. Climate models predict that ice shelves will continue to shrink, reaching a tipping point that could result in a significant period of ice sheet disintegration.
Davison stressed that it is not necessary to reach this tipping point to witness the impact on the planet. The current changes are substantial and have significant consequences. Davison warned, “You don’t need every ice shelf to be basically gone or disappearing for it to matter.”