Last month, we reported on a plan put forth by scientists at Princeton University to slow down melting of the Antarctic ice shelf. One of those plans calls for building dams underwater to direct warmer water away from the ice that slides into the ocean every year and floats on the sea water below. Another proposal is to build artificial islands offshore to support the ice shelf.
Whichever method is preferred, new research suggests the need for some form of remedial action may be called for sooner than thought. A study (pay wall) just published by the Center for Polar Observation and Modelling at the University of Leeds reports the findings of the first ever complete underwater mapping of the ice sheet.
“What’s happening is that Antarctica is being melted away at its base. We can’t see it, because it’s happening below the sea surface,” Professor Andrew Shepherd, one of the authors of the paper, tells The Guardian. “The changes mean that very soon the sea-level contribution from Antarctica could outstrip that from Greenland.”
We know that melting in Greenland and the Arctic is occurring because we can see evidence of it in aerial photographs. When viewed from above, Antarctica appears to have remained quite stable over time, but the new mapping reveals that warmer water underneath is melting the ice sheet from below.
Lead author Hannes Konrad says, “This retreat has had a huge impact on inland glaciers, because releasing them from the sea bed removes friction, causing them to speed up and contribute to global sea level rise.” The study gives the lie to the claims of climate deniers that ice in the Antarctic is actually getting thicker. The study shows that, at best, the ice in some parts of the continent are stable when viewed from above. But even those areas are subject to melting below.
“It should give people more cause for concern,” says Shepherd. “Now that we have mapped the whole edge of the ice sheet, it rules out any chance that parts of Antarctica are advancing. We see retreat in more places and stasis elsewhere. The net effect is that the ice sheet overall is retreating. People can’t say ‘you’ve left a stone unturned’. We’ve looked everywhere now.”
In all, the scientists say the ice shelf decreased in size by 1,463 square kilometers — an area the size of Greater London — between 2010 and 2016. The study measured the Antarctic’s “grounding line” – the bottommost edge of the ice sheet — along 16,000 kilometers of coastline. Archimedes’s principle of buoyancy was applied to elevation data collected by the European Space Agency’s CryoSat-2 satellite to relate the thickness of the floating ice to the height of its surface.
The study found that even a small increase in the temperature of the ocean could lead to 5 meters or more of ice melt per year beneath the surface. The underwater dams proposed by Princeton University are intended to steer that warmer water away from the ice shelf.
This study is just one more bit of evidence that suggests the Earth’s environment has reached a tipping point where it could experience cataclysmic changes in a relatively short time. Should you be scared? Not if you live in Pocatello, perhaps, where warmer temperatures could make Idaho the new Bahamas. If not, you should be terrified. Scientists say if all the ice at both poles melts, ocean levels will rise by 216 feet. Here’s a handy video to help you visualize what that will mean to your heirs, assuming any of them survive.
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