“Estuaries” from the ocean onto the ice can cause fractures and contribute to sea-level rise
Columbia University glaciologist Alexandra Boghosian spent two years studying a meltwater river on Greenland’s Petermann Ice Shelf. She suspected the river ended in a waterfall like the one that cascades off the Nansen Ice Shelf in Antarctica, potentially keeping water from accumulating in melt ponds that can damage the ice. Instead Boghosian and her team discovered a new phenomenon: a deep-cut river channel that could contribute to future ice-calving events and accelerate sea-level rise.
The team first spotted the phenomenon in 2018 using Google Earth; an overhead view showed sea ice floating in a river carving into the ice shelf. Further work confirmed this river had cut so deep its water actually flowed backward, from the sea up to half a mile into the channel. “We called it an ‘estuary’ because of the evidence of this flow reversal that mixes fresh and salt water,” Boghosian says. She and her colleagues detailed their find in Nature Geoscience.
The researchers also noticed ice fractures running parallel to the river along its backward-flowing section. “The type of fractures they found can really set up ice for failure because ocean water can get in there and erode them,” says Catherine Walker, a glaciologist at the Woods Hole Oceanographic Institution, who was not involved with the study. Such fractures can contribute to calving events, in which large blocks crack off a shelf.
Relatively warm water flows in “upside-down rivers” underneath some ice shelves, melting the bottom and letting surface ice settle to form depressions on top. Water flowing through such channels could also make shelves more prone to forming estuaries. “These linear features mean the river is going to form in the same place every year, allowing the water to incise deeper,” Boghosian says.
Most of the world’s ice shelves are in Antarctica and experience less meltwater than Greenland’s do, but climate change could lessen the gap. “I don’t think the volume of meltwater has been able to establish one of these estuaries in Antarctica,” Walker says, “but this study is certainly forward-looking as to what could happen to weaken those big ice shelves.”
Brasil Últimas Notícias, Brasil Manchetes
Similar News:Você também pode ler notícias semelhantes a esta que coletamos de outras fontes de notícias.
California gives rivers more room to flow to stem flood riskCalifornia is on the forefront of a new wave of flood risk management that centers on natural engineering over structural
Consulte Mais informação »
State Project Provides Local Rivers More Room To Flow To Stem Flood RiskThe Dos Rios Ranch Preserve is California's largest single floodplain restoration project, part of the nation's broadest effort to rethink how rivers flow as climate change alters the environment.
Consulte Mais informação »
Strawberries and canned salmon? Creator of ‘Spokane-style’ pizza explains recipe from viral videoStrawberries, bell peppers, onions, fry sauce and canned salmon on a pizza? FOX13
Consulte Mais informação »
Monero Is on Rise with Hashrate and Exchange Inflows Rising Rapidly$XMR is one of the best performing coins on the cryptocurrency market as it shows more than 70% growth in recent months
Consulte Mais informação »
Crypto Funds See Outflows as Bitcoin Gets More 'Interest-Rate Sensitive'Some $97 million flowed out of digital asset funds in the week through April 15 as investors adjusted to a hawkish Fed discussion on shrinking the central bank's balance sheet AngeliqueChen07 reports
Consulte Mais informação »
Global warming is speeding up ocean currents. Here’s whyClimateChange will continue to speed up ocean currents, a new study suggests, potentially limiting the heat the ocean can capture and complicating migrations for already stressed marine life.
Consulte Mais informação »