Antarctica Is Melting. It Has Happened Before
Antarctica is the highest, driest, coldest, windiest, and brightest of the seven continents. It is roughly the size of the United States and Mexico combined and is almost completely covered by a layer of ice that averages more than one mile in thickness, but is nearly three miles thick in places. This ice accumulated over millions of years through snowfall. Presently, the Antarctic ice sheet contains 90% of the ice on Earth and would raise sea levels worldwide by over 200 feet were it to melt, according to NASA.
Antarctica drives much of the Earth’s climate systems. For millennia, cold water from the South Pole has flowed northward through the world’s oceans while heat from the higher latitudes has flowed south toward Antarctica. Those ocean currents influence the complex air currents that control the climate in various parts for the world. This enormous flow of energy is like the cooling system of an automobile where the developed world is the engine and Antarctica is the radiator. Everything is just fine so long as the system operates properly. But what happens when it stops working?
The Importance Of A Few Degrees
We are about to find out. Researchers recently drilled a hole 30 centimeters wide through nearly 600 meters of ice using hot water. Then they lowered instruments to measure temperature and salinity under the glacier. What came next is the biggest part of the story. They inserted Icefin — a robot with a camera — into the hole and were able to see the underside of the glacier for the first time.
What their instruments told them was that there is a thin layer of fresh water that protects the glacier from the warmer (warmer being a relative term) beneath. Therefore, the amount of vertical ice loss was less than predicted. But Icefin revealed the underside of the glacier is riddled with cracks and crevices that look like an upside down staircase. Some of those crevices extend far up into the glacier, making it unstable. Apparently, the insulating effect of the fresh water is diminished in the areas where those cracks and crevices are present.
Peter Davis, an oceanographer at the British Antarctic Survey (BAS) and lead author on one of the two new studies published in the journal Nature, tells The Independent, “Our results are a surprise but the glacier is still in trouble. If an ice shelf and a glacier is in balance, the ice coming off the continent will match the amount of ice being lost through melting and iceberg calving. What we have found is that despite small amounts of melting there is still rapid glacier retreat, so it seems that it doesn’t take a lot to push the glacier out of balance.”
Eric Steig, a glaciologist at the University of Washington in Seattle, says the results highlight ways in which the ice is sensitive to specific factors. Glacial retreat can be rapid — the Thwaites Glacier has receded 16 kilometers since 19990 — despite low rates of melting from underneath. The most pronounced melting is occurring in those cracks and crevasses below the ice, which might encourage large bits of ice to break off. “Maybe you don’t need as much melt to affect the structural integrity,” Steig says.
Warmer Water In Antarctica
Remember how ocean currents affect wind circulation? Those winds can also impact ocean currents. Climate researchers believe changes in wind patterns related to higher average global temperatures are driving a flow of warmer water into the Southern Ocean, which in turn is raising the temperature of the water beneath the ice floes of Antarctica.
Carlos Moffat, an oceanographer at the University of Delaware, has recently returned from a research mission to Antarctica. He tells the Daily Kos he personally witnessed “extraordinary change — what we’ve seen this year is dramatic. Even as somebody who’s been looking at these changing systems for a few decades, I was taken aback by what I saw, by the degree of warming that I saw. We don’t know how long this is going to last. We don’t fully understand the consequences of this kind of event, but this looks like an extraordinary marine heatwave.” He added that it’s “too early, and difficult” to attribute this year’s conditions to long term climate change. That will have to wait until peer reviews of this year’s data are published.
The Octopus & Antarctica
While is it generally assumed that Antarctica was ice-free millions of years ago, climate scientists have often wondered whether the ice sheet was diminished significantly in more recent times, particularly during the interglacial period that occurred about 125,000 years ago.
A team of 11 scientists that includes biologists, geneticists, glaciologists, computer scientists, and ice-sheet modelers have devised an ingenious new way to answer that question. They examined the DNA of the Turquet’s octopus — a species that has been living around the Antarctic continent for about 4 million years. The octopus DNA carries a memory of its past, including how and when different populations were moving and mixing together, exchanging genetic material.
After examining samples from 96 octopuses collected over three decades from around the continent, the scientists say they detected clear signs that some octopus populations on opposite sides of the West Antarctic Ice Sheet had mixed together about 125,000 years ago. The only likely route that would allow the two populations to mix would be a waterway between the south Weddell Sea and the Ross Sea.
“That could only have happened if the ice sheet had completely collapsed,” said Dr Sally Lau, a geneticist at James Cook University who led the research. She tells The Guardian the information on the changes in the DNA of the octopus can be used like a clock, allowing her to pinpoint the period when octopuses in the south Weddell Sea and the Ross Sea were mixing.
Nathan Bindoff, an oceanographer and Antarctic expert at the University of Tasmania who was not involved in the research, told The Guardian that using octopus DNA was “the last way I would have thought of having evidence of large sea level changes coming from the collapse of the West Antarctic Ice Sheet. The loss of that ice sheet would have very real consequences for the whole planet. If this [octopus research] is correct, then there are sensitivities in the Earth system that lead to planetary scale sea level rise. This paper is another piece of evidence that reduces that uncertainty of how this ice sheet has evolved in the past and that is critical for how we think about the future.”
The Takeaway
Most of us don’t spend a lot of time thinking about Antarctica. It’s a big lump of ice surrounding the South Pole. It’s been there forever and it will continue to be there for millions of years to come, right? Well, maybe. The most recent research indicates there are more changes taking place in this frozen part of our world than we ever imagined. The scientific community is trying to identify those changes and help us understand how they will impact human civilization.
If all the ice in Antarctica were to melt, sea levels would be two hundred feet higher than they are today. Think what happens there doesn’t have any effect on humans? Think again.
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