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Antarctic ice sheet crack raises global flood concerns

Fears of a global flood have been raised by the discovery of a 30km crack in the West Antarctic ice sheet – a development which, according to experts and researchers, could lead to an immense rise in sea levels across several continents.

The West Antarctic ice sheet has been under scrutiny for years, with a lot of focus placed on the nature of its stability. There has also been much speculation pertaining to the effects of any further significant ice loss. Now, it seems an event from hundreds of thousands of years ago could give some indication as to what lies in store if the ice sheet were to melt much further than it already has.

The world has three global ice sheets, all of which hold the potential to affect sea level, even if some of the ways in which they do so are quire diverse. The dispersion of rising levels can be spread far from the source, leading to widespread disruption, including damage to ecosystems, adverse weather and, of course, flooding.

Over the past 23 years, there have been three significant collapses in the West Antarctic ice sheet. Larsen A in 1995, Larsen B in 2002 and Larsen C in 2017 (see below).

The West Antarctic Ice Sheet, as depicted in a June 2018 National Geographic article. It highlights where sections have broken off in the recent past. (c) National Geographic

Antarctica has been a cause for great concern in recent years, having lost three trillion tonnes of ice since 1992, melting at three times its previous rate.

Many of these worries stem from a connection which has been made between the ice sheet and sea levels from 125,000 years ago, during ‘the last brief warm period between ice ages’ as Paul Voosen of Science describes it. “Earth was awash,” continues Voosen is his description of these prehistoric events, “Temperatures during this time, called the Eemian, were barely higher than in today’s greenhouse-warmed world. Yet proxy records show sea levels were 6 to 9 meters higher than they are today, drowning huge swaths of what is now dry land.”

At a meeting of the American Geophysical Union, which took place in Washington, D.C earlier this month, experts confirmed that the global flood at that time was caused by the melting West Antarctic ice sheet.

Anders Carlson, a glacial geologist at Oregon State University in Corvallis, who led the recent study said; “We had an absence of evidence,” referring to the connection between global sea levels and the ice sheet, adding “I think we have evidence of absence now.”

Global flood 30km ice crack
A visible 30 km crack in the Pine Island Glacier, a vulnerable part of the Antarctic Ice Sheet has raised the alarm among scientists. (c) NASA/GSFC/METI/ERSDAC/JAROS, AND U.S./JAPAN ASTER SCIENCE TEAM

With the new discovery of a 30 km crack in the Pine Island Glacier, scientists are referring to the events 125,000 years ago as a cautionary tale. Basically put, what happened then can happen again if this ice sheet melts, and the geographical definition of the world will be forever altered as a result. Pine Island Glacier and Thwaites Glacier act as stoppers, or blockers, which are able to contain dense ice mass located further inland from merging with or falling into the ocean. Should they fall away, or crumble, like the Larsen ice sheets and glaciers have done in recent decades, the effects would be devastating.

The West Antarctic Ice Sheet might not need a huge nudge to budge,” Jeremy Shakun, a paleoclimatologist at Boston College said in a recent interview, alluding to the fact that “the big uptick in mass loss observed there in the past decade or two is perhaps the start of that process rather than a short-term blip.”

Records stats that, since 1993, the global ocean watermark has risen by 84.8 mm. Oceans themselves are currently rising by 3.4 millimetres per year.

Without drastic changes, or a drop in global temperatures, the consensus remains that this may not be a tide we can turn back.