Melting ice in Antarctica

Considering how cold it’s been around here recently, global warming sounds not so much like an environmental problem as it does something devoutly to be wished for–but as someone once said, “Be careful what you wish for–you may get it.”

While it’s true that science has yet to come flat out and say that global warming, the anticipated result of mankind’s pumping of billions of tonnes of heat-trapping carbon dioxide and other gases into the atmosphere every year, has unequivocally begun, the evidence is mounting–and one place where the evidence may soon become crystal clear is Antarctica.

As far back as 1978, a paper in the science journal Nature suggested that scientists would see the first evidence of global warming in Antarctica. And what they’ve seen in the last few years is exactly what they would expect if global warming were already underway–although, they always hasten to add, there’s still a possibility that the changes Antarctica is undergoing are related to some natural cycle we don’t know about yet.

But those changes are massive. Over the whole of Antarctica, temperatures have increased an average of about one degree Celsius over the past 50 years, according to David G. Vaughan, a glaciologist at the British Antarctic Survey in Cambridge, England–and on the Antarctic Peninsula, which extends outward toward the southern tip of South America, temperatures have risen an average of 2.5 degrees Celsius since record-keeping began in the 1950s.

As a result, massive ice shelves have begun to break up. Between January 14 and February 27 last year, an ice shelf that formerly blocked the Prince Gustav Channel between James Ross Island and the peninsula broke up, which means that, for the first time in recorded history, James Ross Island can be circumnavigated.

During the same period, the northern section of another ice shelf, the Larsen, disintegrated, crumbling into a plume of debris extending 200 kilometres. And further south, an iceberg roughly the size of Luxembourg–37 kilometres wide, 77 kilometres long and 183 metres thick–also calved off the Larsen Ice Shelf. Another huge ice shelf, the Wordie, has also recently disappeared.

Although the giant iceberg drew the most media attention, the real shocker to scientists was the disappearance of the ice shelves. If you have an old–or even a new–school atlas lying around, you’ll see those vanished ice shelves included on the map of Antarctica as permanent fixtures. That they could collapse in such a relatively short period of time could be an ominous harbinger of other dramatic changes soon to come as the planet warms up.

The disappearance of the ice shelves isn’t the only change to Antarctica. On another ice shelf, the Wilkins, summer–defined as the period during which ice melts (which is a pretty good definition for Saskatchewan, too, actually) has increased from 60 to 90 days in just over a decade. As well, parts of the “white continent” are becoming increasingly green. Antarctica has only two species of flowering plant. Since 1964, the Antarctic pearlwort has increased sixfold, and Antarctic hairgrass has become 25 times more common.

So why aren’t scientists absolutely convinced that all this is related to global warming? Because the Antarctic Peninsula is more prone to temperature fluctuations than most places, due to the complex interactions of winds, ocean currents and ice. Nevertheless, what’s happening there matches very well with predictions of global warming’s effects.

Scientists would like very much to know what happened to the Antarctic ice cap in the Pliocene Epoch, three to four million years ago, when the Earth was approximately as warm as mankind’s efforts may make it in the next few centuries. If the Antarctic ice cap melted then, it may melt again–and that would be a disaster of unimaginable proportions, because the Antarctic ice cap averages 2.5 kilometres in depth, and if it melted, it would raise the sea level by 74 metres–which means you could take a boat to the 20th story of the Empire State Building.

At the moment, scientists aren’t sure what will happen, because even though the ice shelves seem to be slowly disintegrating, they don’t effect the sea level. It’s the land-based glaciers that could cause the problem, and at the moment, scientists don’t even know whether the ice sheet is getting thicker or thinner. They’ve begun the process of finding out, however, and the results of that data should be of great concern to all of us.

If the melting of Antarctica truly is underway, a lot more than just that continent’s shorelines are going to change.

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