Antarctic Researchers Say a Marine Heatwave Could Threaten Ice Shelves

An anonymous reader shares an article that originally appeared on Inside Climate News, a nonprofit independent news organization that covers climate, energy, and the environment. It was republished with permission via Ars Technica. Here's an excerpt: Research scientists on ships along Antarctica's west coast said their recent voyages have been marked by an eerily warm ocean and record-low sea ice coverage -- extreme climate conditions, even compared to the big changes of recent decades, when the region warmed much faster than the global average. Despite "that extraordinary change, what we've seen this year is dramatic," said University of Delaware oceanographer Carlos Moffat last week from Punta Arenas, Chile, after completing a research cruise aboard the RV Laurence M. Gould to collect data on penguin feeding, as well as on ice and oceans as chief scientist for the Palmer Long Term Ecological Research program. "Even as somebody who's been looking at these changing systems for a few decades, I was taken aback by what I saw, by the degree of warming that I saw," he said. "We don't know how long this is going to last. We don't fully understand the consequences of this kind of event, but this looks like an extraordinary marine heatwave." If such conditions recur in the coming years, it could start a rapid destabilization of Antarctica's critical underpinnings of the global climate system, including ice shelves, glaciers, coastal ecosystems, and even ocean currents. Such radical changes have already been sweeping the Arctic, starting in the 1980s and accelerating in the 2000s. Data collected during Moffat's most recent research voyage includes the first readings from temperature and salinity sensors that were deployed a few years ago, which will give the scientists a starting point for comparisons. Moffat said it's "too early, and difficult" to attribute this year's conditions to long-term climate change until some peer-reviewed results are published. "But it seems to me that this might be a really unprecedented event," he said. "These episodes of relatively rapid ocean warming that can persist for months have been occurring all over the place. They haven't been common in this region." He said ocean temperature readings going back to April 2022 speak to the persistence of the warm conditions off the Antarctic Peninsula. The cruise covered an area more than 600 miles long and crisscrossed waters above the 125-mile wide continental shelf, documenting widespread ocean heating. "That's a very significant region," he said. "We don't have data going back 30 years for the entire region. But for the parts of the shelf for which we do have that data, it really seems extraordinary. It's very difficult to warm the ocean, and so when we see these conditions, that really speaks to a very intense forcing."

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