An ice sheet in West Antarctica previously found to be capable of increasing the sea level by as much as 10 feet underwent unexpectedly significant melting last year, and an unexpected rainfall is at least partially to blame, according to a newly-published Nature Communications paper.
In fact, the study authors found that a Texas-sized area of the Ross Ice Shelf – the largest chunk of floating ice on Earth – experienced an unusual degree of thawing in 2016, with pools of water remaining on the surface for up to 15 days at a time, The Verge reported on Thursday.
The melting is being blamed on a particularly strong El Niño event which, over the course of the past two years brought unexpectedly warm and moist air into the region. The heat, along with the unexpected rainfall, causes meltwater to pool and persist – which is problematic because it could cause thawing to accelerate, the website explained.
“It provides us with a possible glimpse of the future,” study author David Bromwich, a senior research scientist at the Byrd Polar and Climate Research Center and Polar Meteorology Group at Ohio State University, explained during an interview with the Washington Post.
“You probably have read these analyses of West Antarctica,” he added. “Many people think it’s slowly disintegrating right now, and it’s mostly thought to be from the warm water eating away at the bottom of critical ice shelves. Well, that’s today. In the future, we could see action at the surface of these ice shelves as well from surface melting. So that makes them potentially much more unstable.”
Event could demonstrate how future melting will occur
As The Verge pointed out, this is not the first time that an El Niño event has caused melting on the surface of the Ross Ice Shelf, but this time, Bromwich and his colleagues noted that it lasted far longer. That, in turn, could cause surface snow to melt, and combined with the unanticipated rainfall, the phenomenon could increase the risk of the ice shelf fracturing.
The study authors tracked the melting event from afar using a monitoring station they had set up in West Antarctica, according to the Post. That station detected a marked increase in atmospheric temperatures, as well as the presence of clouds containing large amounts of moisture. Bromwich then used satellite and microwave data to determine the event’s impact on the ice shelf.
They determined that liquid water had mixed into snow covering the landscape, creating slush. For now, the additional rainfall and moisture does not appear to have had any adverse effect on the Ross Ice Shelf, which has since become fully frozen again, the researchers noted. However, the event has caused some concern, as it fits with a previously published study which suggested that major ice loss in the region could increase the sea level by four feet this century.
In that study, Rob DeConto of the University of Massachusetts-Amherst and David Pollard of Penn State University indicated that while melting in West Antarctica is currently caused mostly by warming waters from below, the phenomenon could speed up due to liquid water from above seeping downward into the ice shelves and causing them to break apart.
“These big melting events that we were studying in this paper is in exactly one of the critical areas that the DeConto and Pollard paper modeled big retreat in the Antarctic ice sheet,” noted Bromwich. “So that’s a big significance here. It kind of shows how these big events could take place in the real world, not just the modeled world… I would say this shows in perhaps a more realistic way, how melting could proceed in the future.”
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