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Northern Now - Winter 2006
NIU plays large role in $30 million effort to unlock climate secrets buried beneath the Antarctic sea
by Tom Parisi
The snows of Kilimanjaro, the 11,000-year-old ice cap atop Africa’s tallest peak, made famous by Ernest Hemingway, might disappear within the next decade. Halfway across the globe in Montana, the number of glaciers in Glacier National Park already has dwindled from 150 to 30 over the course of less than a century.
Near the top of the world, at the edge of the Arctic Circle, the island village of Shishmaref, no longer shielded from storm surges by sea ice and built on permafrost, is eroding into the Bering Sea. At the other polar extreme, edges of the Antarctic ice sheet are melting into the ocean, raising fears of a rise in global sea levels.
With global warming now recognized by most scientists as one of the top threats facing our planet, researchers are turning their attention to determining its causes, the rate of warming and its ramifications for our future. Few efforts in coming years will be more ambitious and larger in scale than a $30 million project led in part by Northern Illinois University geologist Ross Powell.
Powell is co-leader and co-chief scientist for the U.S. contingent of ANDRILL, a geologic drilling project that will involve 150 researchers worldwide, including at least half a dozen NIU scientists and students. ANDRILL aims to unravel mysteries of global warming by unlocking clues buried in one of the most remote, hard-to-reach regions of our planet: the vast seabed beneath the Antarctic sea.
“The layers of geologic strata in the Antarctic seabed have a story to tell us that goes back millions and millions of years,” Powell says. “It’s a story about the earth’s cycles of warming and cooling, and like all good histories, this one will help us to better understand and prepare for the future.”
NIU and the University of Nebraska at Lincoln lead a group of top U.S. universities involved with ANDRILL, while the project’s international half is made up of researchers from New Zealand, Italy and Germany. After eight years of planning, scientists are preparing to drill into the seabed this coming fall and during the fall of 2007. The drill sites are located in or near McMurdo Sound, a historic staging point for exploration and scientific investigation in the southwestern Ross Sea.
Awful, beautiful place
The scientists will retrieve sediment cores that will help explain how the Antarctic ice sheets behaved during past warming and cooling trends. The polar regions are more sensitive to climate change than other parts of the world, and the massive ice sheets generate trails of evidence about climate history. Because the Antarctic ice sheet is by far the world’s oldest and largest, the continent holds a treasure trove of information, albeit hidden in the recesses of a brutal, unforgiving environment.
British naval officer Robert Falcon Scott famously said of the Antarctic, “Great God, this is an awful place!” Holed up in a tent during a fierce blizzard on the Ross Ice Shelf, he drew his last breath in March of 1912. Norwegian explorer Roald Amundsen, whose team months earlier had beaten Scott’s men in the quest to first reach the South Pole, was awed by its icy majesty. “The land,” he said, “looks like a fairy tale.”
Antarctica is about 1.5 times the size of the United States. It is an isolated landscape of regal Emperor penguins and surly Leopard seals, spontaneous whiteouts and vast blue skies, plunging crevasses and towering ice mountains, smoldering volcanoes and bitter cold, howling wind and otherworldly stillness. More than 95 percent of the continent is covered by ice that can be up to three miles thick.
“The polar regions are different from anything you’ve experienced,” says Powell, who has traveled to the Antarctic on 10 previous research expeditions. “Even for scientists, the Antarctic region is somewhat of a mystery.We know so little about the history of how the ice has behaved because the records we have from past drilling operations are fragmentary. Yet, it’s such a big mass of ice, understanding what can happen and how fast it can react to warming is really important.”
Geologic drilling operations that began in the 1970s have produced much of what is known about the continent’s history. Scientists now know the Antarctic ice sheet is more than 35 million years old, but they believe the current extremely cold climate has existed for only 3 million years. Through most of its history, the continent has been ice-free, even warm enough at one time to accommodate dinosaurs.
Today the Antarctic ice sheet, divided into east and west lobes, accounts for some 60 percent of the world’s freshwater. If it were to entirely melt, it would raise the level of the world’s oceans by nearly 200 feet.
The “global thermostat”
“Understanding the earth’s potential for global climate change is one of the most important scientific challenges of our age,” says Thomas Wagner, program director for the Antarctic Geology and Geophysics Program of the National Science Foundation, which is supporting ANDRILL to the tune of $20 million. (The agency’s average research allocation is $400,000.) The project also will be among the world’s largest during International Polar Year (2007-09), a coordinated campaign of research designed to initiate a new era in polar science.
“ANDRILL will give us the best information to date on the role of the Antarctic ice sheet in global climate change,”Wagner says. “It’s a profound role, being the major player in sea-level change and feeding back on ocean and atmospheric circulation.”
Powell likens the Antarctic to a “global thermostat.”
The continent’s massive ice sheet interacts with the world’s atmosphere and oceans to help maintain worldwide temperature distributions.When global temperatures warm past critical thresholds, the ice sheet melts, accelerating the warming effect. When global temperatures cool, the ice sheet expands, accelerating the cooling effect.
“Scientists understand the world is warming because of an increase in carbon dioxide in our atmosphere, or the greenhouse effect,” Powell says. “Our challenge is to determine where we are in that natural cycle of warming and cooling, the rate at which we’re warming and the significance and consequences of mankind’s role. Answers to these questions will help scientists predict the future consequences of global warming.”
Evidence of warming
According to the National Academy of Sciences, the earth’s surface temperature has risen by about 1 degree Fahrenheit over the past century, with the strongest warming effect occurring in the past two decades. A United Nations’ panel on climate change has projected a rise in global temperature, mostly because of greenhouse warming, of between 2.5 and 10.5 degrees Fahrenheit by 2100. In addition to its impact on sea levels, continued global warming could influence everything from agriculture and air quality to energy usage and the spread of disease.
“If those projections of warming trends are correct, the world’s climate within the next few centuries will be at a point equivalent to conditions on our planet tens of millions of years ago, before Antarctica became cold enough to support the big ice sheets that are there today,” Powell says. “Sea levels are already rising on the order of millimeters a year—that’s well documented. If the trend continues at that rate or faster, eventually coastal cities from Venice (Italy) to New Orleans are going to have to do something to mitigate the rise.”
A growing body of evidence indicates that the world’s oceans are warming as well, according to NIU geologist Paul Loubere, an international authority on the role of oceans in climate change.
“A number of scientific surveys show us that the temperature of the deep ocean has been increasing, on the order of a tenth of a degree centigrade over the past 30-odd years,” Loubere says. “That might not seem like a large increase, but to change the temperature of the deep ocean even by that much requires an enormous amount of heat because of the enormous amounts of water in our oceans. The message without a doubt is that heat has been accumulating in the earth’s atmosphere and in the oceans over centuries.”
Like cake layers
Scientists don’t expect the warming atmospheric and oceanic temperatures to melt the entire ice mass over the South Pole in the foreseeable future, but there is real concern over the West Antarctic Ice Sheet. It is grounded well below sea level and is considered potentially unstable. That region will be the focus of this fall’s drilling effort, led by Powell and Tim Naish of the Institute of Geological and Nuclear Sciences in New Zealand.
The drill site is located on the Ross Ice Shelf extending from Ross Island, off the Antarctic coast (see circled area on p.14 map.) Fed by glaciers, ice shelves are large floating bodies of ice. They are extremely sensitive early indicators of climate change. Roughly the same size as Texas, the Ross Ice Shelf is the world’s largest. It is considered stable but appears to be undernourished, which could be cause for concern. Scientists believe the demise of the Ross Ice Shelf would be an important precursor to eventual collapse of the entire West Antarctic Ice Sheet.
Drill operators and scientists will work in the shadow of Mt. Erebus, an active volcano towering 12,500 feet above the Ross Sea. Mt. Erebus and two inactive volcanoes make up Ross Island. The volcanoes played an important role in the unique confluence of geologic events that created the time capsule that ANDRILL researchers seek to open.
Deep processes within the earth tore at the tectonic plates beneath the continent, creating rifts that were further deepened by the weight of the dying volcanoes, sinking back into the crust as they cooled and creating a moat-like depression around Ross Island. During repeated warming and cooling cycles over tens of millions of years, the massive ice sheet ground back and fourth. It deposited glacial sediments into those rifts with each advance, and ocean sediments with each retreat, like alternating layers of a cake.
The presence of volcanic ash in those ancient layers provides scientists with key chemical signatures for dating sediments. The remains of microscopic marine life further give researchers critical knowledge about everything from ancient water temperatures and water depth to floating ice conditions.
Drilling through time
During the first season of drilling, core samples are expected to provide scientists with their first high resolution picture of climate fluctuations dating back from the present day to 5 million years ago. “To my mind, the record of climate change over the last few million years is most relevant to understanding our modern climate and predicting where it’s headed in the future,” says Reed Scherer, an NIU geologist and key member of the ANDRILL team.
Scherer’s expertise lies in the study of fossil diatoms, microscopic single-celled algae that live in surface or shallow waters, evolve rapidly and are eventually deposited on the ocean floor. “The variety of diatoms is linked to water temperature,” Scherer says. “So we can track changes in water temperature based on the different species of diatom fossils that we find in the layers of sediment from the rock cores. In essence, they provide a record of climate and environmental change in the region through time.”
Past Antarctic research conducted by Scherer drew a startling conclusion: that the West Antarctic Ice Sheet did indeed disappear and then reform sometime within the past million years. “I think the last time the West Antarctic Ice Sheet disappeared was 400,000 years ago, when the planet experienced an unusual warm period,” Scherer says. “If such an event occurred today, it would increase sea levels by 18 feet. Most of the Netherlands and Bangladesh and most of Florida and Manhattan would be under water.”
Other ANDRILL drilling sites over the next two seasons will seek to recover sediment cores for periods of time going back 20 million years. Sites also are being investigated that would take the record back to 60 million years.
“With each change in drilling location, we tap into very different sequences representing windows of geologic time preserved from erosion,” says Powell, who expects the ANDRILL team to unearth the unexpected. “Just about every drilling project produces revelations that create revolutions in scientific thought. Even though we have specific objectives, we are hoping and expecting to be surprised.”
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