NASA’s IceBridge operation for this Antarctic summer has discovered that the Pine Island Glacier is in the process of calving a massive iceberg — 880 square kilometres of the floating glacier tongue is about to go floatabout, leaving the glacier snout shorter than any time since its position was first recorded in the 1940s. The crack was first spotted by a flight on October 14, and surveyed during a flight on the 28th — featured in the video above. NASA’s Earth Observatory has more pictures and commentary, and there’s a background piece for the video at the NASA IceBridge news page. See also the NASA Ice Fickr stream and NASA Explorer Youtube channel.
Tag: Pine Island Glacier
Fraser’s Penguins
I decided to read Fen Montaigne’s book Fraser’s Penguins: A Journey to the Future in Antarctica because of what I understood it would have to say about climate change. It does say very important things on that subject, but along the way it proved a fascinating account of the life of the Adélie penguins of the Antarctic Peninsula and of the scientific monitoring which has recorded the welfare of their colonies in the vicinity of Palmer Station for more than three decades. As well, the author provides memorable descriptions of the land, sea and skyscapes and the pleasure he took from them. His weaving in some of the impressions of the early Antarctic explorers added interesting historical perspective. The book is a rewarding read on many fronts.
Warming at the walls of the “citadel of ice”
Australian-born writer Meredith Hooper was looking for “a route into the complex business of the Earth’s changing climate” when she spent January to March 2002 at Palmer Station on the west coast of the Antarctic Peninsula. She watched and chronicled the work of scientist Bill Fraser and his team who for years have studied the Adélie penguins breeding on nearby islands over the summer months.
I read the account of her time there in her book The Ferocious Summer. It was the summer when the Larsen B ice shelf on the eastern side of the Peninsula spectacularly disintegrated. Her often poignant story tells of diminished numbers of penguins arriving for breeding, weather conditions inappropriate for their nesting, poor nutrition levels and low fledgling survival rates.
The book was also an illuminating account of the working and thinking of the scientists as they gradually amass and interpret the years of data needed for a proper understanding of what is happening to wildlife populations under the inexorable processes of climate change.
Hooper wrote for any who want to understand what global warming might mean for specific places and the life which has developed in close relationship with them. She observes that “climate change isn’t a blanket thrown evenly over the surface of the Earth”. Its impacts are variable and often need to be understood locally.
In the vulnerability of the Adélie penguins she saw a small example of a potentially vast reality ahead. “In one sense, they had become surrogate humans.” Her book was yet another solemn warning from the world of science.
Now another book has appeared by a writer who also spent several months with Bill Fraser’s team. Fraser’s Penguins is written by Fen Montaigne, senior editor of the online Yale 360. I hope to be reading and reviewing it in the near future. But in the meantime I wanted to draw attention to a report he has just written for Yale 360, The Warming of Antarctica: A Citadel of Ice Begins to Melt. Its focus is much wider than the Adélie penguins, though they figure in it: amongst other things he notes that their population has declined from 30,000 breeding pairs in 1975 to 5,600 pairs today.
On the broader Antarctic picture Montaigne explains helpfully for the general reader the developing scientific understanding of the effects of warming on the ice. He begins with a prescient quote from a geologist, John H. Mercer, writing in Nature in 1978.
“If present trends in fossil fuel consumption continue, a critical level of warmth will have been passed in high southern latitudes 50 years from now, and deglaciation of West Antarctica will be imminent or in progress… One of the warning signs that a dangerous warming trend is under way in Antarctica will be the breakup of ice shelves on both coasts of the Antarctic Peninsula, starting with the northernmost and extending gradually southward.”
Montaigne observes that Mercer’s prediction has come true, a couple of decades earlier than he anticipated. Since Mercer wrote those words eight ice shelves have fully or partially collapsed along the Antarctic Peninsula, and the northwestern Antarctic Peninsula has warmed faster than virtually any place on Earth.
Montaigne continues:
“The question now, as humanity pours greenhouse gases into the atmosphere at an accelerating rate, is not whether Antarctica will begin to warm in earnest, but how rapidly. The melting of Antarctica’s northernmost region – the Antarctic Peninsula – is already well underway, representing the first breach in an enormous citadel of cold that holds 90 percent of the world’s ice.
He acknowledges the vastness and coldness of the Antarctic ice dome, the heart of which is not likely to begin to melt any time soon. But the periphery is another matter, and on that periphery the Antarctic peninsula has warmed faster than any other place. A 60-year temperature record at a research base on the northwest shows winter temperatures 11 degrees F higher and annual average temperatures 5 degrees F higher.
Ninety percent of 244 glaciers along the western Antarctic Peninsula have retreated since 1940. Sea ice covers the Southern Ocean off the western Antarctic Peninsula three fewer months a year than in 1979, according to satellite data. In addition, ice shelves have been disintegrating up and down the peninsula.
He quotes Ted Scambos, the lead scientist at the National Snow and Ice Data Center in Boulder, Colorado.
“We are already at the point where the changes we’re seeing in this part of Antarctica are unprecedented throughout the entire period of human civilization.”
Turning to the Pine Island and Thwaites glaciers further south, Montaigne discusses the effect of warming water. Changing atmospheric and oceanic circulation patterns have caused the water of the deep Antarctic Circumpolar Current to be funnelled up onto the continental shelf in western Antarctica. At 37 degrees F in winter, it is warmer than the surface water and much warmer than air temperatures. It’s a huge volume and is having an enormous impact. In relative terms it is described as “blisteringly hot” by Douglas Martinson, an oceanographer and Antarctic specialist at Columbia University’s Lamont-Doherty Earth Observatory.
The thinking of Robert Bindschadler, a senior fellow at the Goddard Space Flight Center and an expert on Antarctic ice, is that the warmer waters are melting the submerged undersides of the ice shelves attached to the Pine Island and Thwaites glaciers, causing them to grow thinner. The melting is effectively loosening the grip of the Pine Island Glacier on the sea floor, causing the vast river of ice behind it to accelerate into the sea. It is now moving at a rate of about two miles a year.
Montaigne reports Bindschadler as saying that if all the ice from the ice streams feeding the Pine Island and Thwaites glaciers were to flow into the Southern Ocean, global sea levels could increase by five feet, inundating low-lying coastal areas from Florida to Bangladesh. “Such an event, said Bindschadler, “could happen in the next half-century.”
The warming of the Antarctic is already bad news for ice-dependent penguin species. It will also be bad news for humanity if we mindlessly continue our assault on the citadel of ice.
Tipping and other points
During the Copenhagen kerfuffle a lot of interesting stuff hit the web: here’s something that deserves a bit more air – a Proceedings of the National Academy of Science (PNAS) special issue on tipping elements in the earth system, edited by John Schellnhuber, the director of the Potsdam Institute for Climate Impact Research in Germany.
Tipping elements (or points, as Malcolm Gladwell would have them) are changes that once started take on a life of their own, and can’t easily be returned to their original state. In the climate system that might be the rapid loss of an ice sheet in a few decades or hundreds of years, while regrowing it might take many thousands. The PNAS special issue deals with nine: dust production in the Bodélé Depression in Chad, ENSO, Arctic sea ice and ice sheets, the Atlantic Meridional Overturning Circulation, deep ocean hydrates (not shallow sea bed, Siberian methane) — David Archer dubs them a “slow tipping point”, the Amazon rainforest (no “Amazongate” here, just a confirmation that concern is justified), monsoons, oceans, and policy responses to the climate challenge. And the best thing is that all the articles are available online, free (click on the link above). Schellnhuber contributes an introduction, and the Potsdam press release also provides a good overview. For some introductory thoughts, check out Tim Lenton’s discussion here.
Another recent example of a real tipping point is the Pine Island Glacier in West Antarctica. Recent modelling suggests that the glacier’s grounding line retreated beyond a ridge in 1996, and is now free to retreat by several hundred kilometres inland. This could happen in a hundred years and result in the loss of half of the ice in the glacier — enough to raise sea level by 24cm. New Scientist reports:
Observations already show that the model severely underestimates the rate at which PIG’s grounding line is retreating, says Katz. “Ours is a simple model of an ice sheet that neglects some important physics,” says Katz. “The take-home message is that we should be concerned about tipping points in West Antarctica and we should do a lot more work to investigate,” he says.
Amen to that.
More than a metre
Sea level will rise by more than a metre by 2100 according to the authors of the third chapter in the World Wide Fund for Nature’s new Arctic report, introduced by Gareth a few days ago. Eric Rignot, one of the two authors of the chapter, is principal scientist for the Radar Science and Engineering Section at NASA’s Jet Propulsion Laboratory, Pasadena, Calif. The other author, Anny Cazenave, is an internationally renowned research scientist from France’s national centre for space studies.
The value of the chapter is that it draws together, authoritatively and coherently, the evidence that points to considerably more sea-level rise over this century than projected in the 2007 IPCC Fourth Report (AR4). Happily politicians are taking IPCC reports much more seriously than in the past, but they should not rest on them. Their responsibility is to be up to date with what the science is saying now. The WWF report assesses the most recent science, and finds that the impacts of warming will be more severe than indicated by the IPCC.
What follows is a summary of the main points made by the chapter.