Tanker traffic that carries roughly 15% of U.S. crude oil passes through Prince William Sound, where huge chunks of ice break away from glaciers and pose risks to ships. Some of the largest icebergs in the Northern Hemisphere are found in the area, and climate change is melting glaciers faster, U.S. Geological Survey (USGS) scientists said.
A newly published study suggests icebergs in the sound are changing shape, with more pieces of smaller sizes than in the past. That poses a different threat to tankers because ships may have an easier time finding routes around larger icebergs, but those tactics may not work as well for the more scattered, smaller ones, the scientists said.
Climate change “creates a whole new situation for ship captains” negotiating a path through the ice, said Anthony Arendt, a USGS scientist and author of the study that was published in the journal Geophysical Research Letters.
More than three decades after the 1989 Exxon Valdez tanker oil spill that devastated marine wildlife in Prince William Sound, climate change is posing new challenges to the oil industry in the region, Arendt said.
“These changing conditions are certainly not on anybody’s navigation chart,” he said.
The study compared how sea ice and icebergs behaved in the sound during two periods: 2002-03 and 2019-20. During the more recent period, glaciers were losing ice at a faster rate and fewer icebergs were attached to glaciers, the study found.
The number of days during summer that icebergs were present in at least one location within the sound increased by 50%, and the total number of icebergs counted per day jumped 95%, according to the study.
The study provides the most detailed look yet of the changing physical properties of icebergs and sea ice in Prince William Sound, Arendt said.
The number and size of icebergs in Antarctica and Greenland have increasingly drawn the attention of scientists as climate change accelerates the melting of the polar regions. Icebergs breaking off glaciers in those regions are not as prevalent as in Prince William Sound, but they are far larger and pose a serious risk to cruise ships and other vessels, particularly in glacier-lined fjords, Arendt said.
