Scientists around the globe conducted a study which found that part of the world’s largest ice shelf is melting at an unpredictable speed 10 times faster than previously estimated. They believe this rapid melting is caused by the solar heating of the global ocean.
Researchers studied Antarctica’s Ross Ice Shelf, which is about as large as France. They spent years trying to learn how the northwestern sector of the ice shelf interacts with the ocean. Their results were published in the journal Nature Geoscience.
“The stability of ice shelves is generally thought to be related to their exposure to warm deep ocean water, but we’ve found that solar heated surface water also plays a crucial role in melting ice shelves,” author Dr. Craig Stewart of New Zealand’s National Institute of Water and Atmospheric Research (NIWA) in New Zealand said in a statement.
“Previous studies have shown that when ice shelves collapse, the feeding glaciers can speed up by a factor or two or three,” added co-author Dr. Poul Christoffersen of Cambridge University’s Scott Polar Research Institute. “The difference here is the sheer size of Ross Ice Shelf, which over one hundred times larger than the ice shelves we’ve already seen disappear.”
Researchers analyzed four years’ worth of data gathered via oceanographic mooring which was deployed under the Ross Ice Shelf. They measured temperature, salinity, melt rates and ocean currents.
The results suggest the world’s largest ice shelf is affected by solar-heated surface water which flows through the cavity under the ice shelf. As a result, the melt rates almost triple during the summer. Additionally, the study suggests that the conditions in the ice shelf cavity are connected with the surface ocean and atmosphere temperature more than previously suspected.
“Climate change is likely to result in less sea ice, and higher surface ocean temperatures in the Ross Sea, suggesting that melt rates in this region will increase in the future,” Stewart said.
A thin, but important layer of the world’s largest ice shelf appears to be melting rapidly where the ice pushes against nearby Ross Island. The pressure exerted by the island is transmitted through the region, which slows the flowing of the entire ice shelf.
“The observations we made at the front of the ice shelf have direct implications for many large glaciers that flow into the ice shelf, some as far as 900 km away,” Christoffersen said.
The researchers consider the Ross Ice Shelf to be relatively stable and not endangered by climate change. However, the new findings suggest it may be more vulnerable than previously thought.
The findings also don’t indicate that the world’s largest ice shelf has become unstable. The researchers say their study suggests that the ice shelf evolved over time so that the ice it is losing is balanced by large inputs of ice from glaciers and snow accumulation. However, it is Ross Island which contributes to this stability right now, and the new study suggests that the island could one day make the ice shelf vulnerable.