Researcher part of critical team studying glaciers and climate change

Brad Danielson and Alex Gardner during time-lapse camera setup in spring 2007.
Brad Danielson and Alex Gardner during time-lapse camera setup in spring 2007.

University of Ottawa geography professor Luke Copland is among researchers from 17 countries studying 19 Arctic tidewater glaciers to better understand how they react to climate change.

The international GLACIODYN project, which is part of the International Polar Year, is concerned with the effect of climate change on tidewater glacier flow, which increases the amount of freshwater pouring into oceans thus causing a rise in sea levels.

Tidewater glaciers drain directly into the ocean from large ice caps and ice sheets such as Greenland. Over the past decade, these glaciers have experienced accelerated ice flow and increased rates of mass loss by iceberg break-up. GLACIODYN researchers want to find out why.

In Canada, seven glaciologists have been working on the Belcher Glacier, a tidewater outlet of the Devon Island ice cap in the Arctic. The research team spent three months in the spring and summer of 2007 on the Belcher Glacier and will be going back in 2008. Their main task is to collect field data to develop a numerical model of the glacier, which will allow them to simulate and explain how it responds to climate change. The field research is augmented by remote sensing data, which will be used to apply field measurements to the scale of the whole glacier system.

“When we look at how glaciers and ice caps respond to climate change we know that their surface melting will increase” explains co-PI Dr. Luke Copland of the University of Ottawa, “but until recently we didn’t realize that glaciers may also respond by speeding up due to increased meltwater lubrication of the glacier bed. This can result in a much more rapid loss of ice from an ice cap than melting alone.”

So far the team has used ice-penetrating radar to measure ice thickness and map the topography under the ice. Researchers also installed time-lapse cameras to monitor the development of surface meltwater drainage systems and the break-up of icebergs during the summer melt season. They used global positioning systems (GPS) to measure ice movement, and installed automated weather stations to record local conditions.

The data will allow scientists to explore how the increased amount of meltwater draining into the glacier as the climate warms will affect the rate of ice flow and the subsequent break-up of icebergs.

A team led by Dr. Luke Copland, Director of University of Ottawa’s new Laboratory for Cryospheric Research, will be heading to Devon Ice Cap in May 2008 to make measurements for the GLACIODYN project. One of three teams to visit the glacier next summer, Copland’s will include two graduate students and one northern undergraduate student who will be using the fieldwork results towards their degrees. This will be the first major field expedition for the Laboratory for Cryospheric Research, which opened in September 2007 with funding from the Canadian Foundation for Innovation and Ontario Research Fund.

The Canadian GLACIODYN team also received substantial support from researchers using the Canadian research icebreaker CCGS Amundsen. They mapped the seabed topography and measured ocean conditions in the water at the glacier snout, giving the team information about what’s happening under the front of the glacier, and how it affects the ice surface.

New Tibetan Ice Cores Missing A-Bomb Blast Markers; Suggest Himalayan Ice Fields Haven’t Grown In Last 50 Years

Operation Redwing was a United States series of 17 nuclear test detonations from May to July 1956
Operation Redwing was a United States series of 17 nuclear test detonations from May to July 1956

Ice cores drilled last year from the summit of a Himalayan ice field lack the distinctive radioactive signals that mark virtually every other ice core retrieved worldwide.

That missing radioactivity, originating as fallout from atmospheric nuclear tests during the 1950s and 1960s, routinely provides researchers with a benchmark against which they can gauge how much new ice has accumulated on a glacier or ice field.

In 2006, a joint U.S.-Chinese team drilled four cores from the summit of Naimona’nyi, a large glacier 6,050 meters (19,849 feet) high on the Tibetan Plateau.

The researchers routinely analyze ice cores for a host of indicators – particulates, dust, oxygen isotopes, etc. — that can paint a picture of past climate in that region.

Scientists believe that the missing signal means that this Tibetan ice field has been shrinking at least since the A-bomb test half a century ago. If true, this could foreshadow a future when the stockpiles of freshwater will dwindle and vanish, seriously affecting the lives of more than 500 million people on the Indian subcontinent.

“There’s about 12,000 cubic kilometers (2,879 cubic miles) of fresh water stored in the glaciers throughout the Himalayas – more freshwater than in Lake Superior,” explained Lonnie Thompson, distinguished university professor of earth sciences at Ohio State University and a researcher with the Byrd Polar Research Center on campus.

“Those glaciers release meltwater each year and feed the rivers that support nearly a half-billion people in that region. The loss of these ice fields might eventually create critical water shortages for people who depend on glacier-fed streams.”

Thompson and his colleagues worry that this massive loss of meltwater would drastically impact major Indian rivers like the Ganges, Indus and Brahmaputra that provide water for one-sixth of the world’s population.

Thompson outlined his findings in an address at the annual meeting of the American Geophysical Union in San Francisco this week.

The Beta radioactivity signals – from strontium90, cesium136, tritium (hydrogen3) and chlorine36 – are the remnants of radioactive fallout from the 1950s-60s atomic tests. They are “present in ice cores retrieved from both polar regions and from tropical glaciers around the globe and they suggest that those ice fields have retained snow (mass) that fell during the last 50 years,” he said.

“In ice cores drilled in 2000 from Kilimanjaro’s northern ice field (5890 meters high), the radioactive fallout from the 1950s atomic test was found only 1.8 meters below the surface.

“By 2006 the surface of that ice field had lost more than 2.5 meters of solid ice (and hence recorded time) – including ice containing that signal. Had we drilled those cores in 2006 rather than 2000, the radioactive horizon would be absent – like it is now on Naimona’nyi in the Himalayas,” he said.

In 2002 Thompson predicted that the ice fields capping Kilimanjaro would disappear between 2015 and 2020.

“If what is happening on Naimona’nyi is characteristic of the other Himalayan glaciers, glacial meltwater will eventually dwindle with substantial consequences for a tremendous number of people,” he said.

Scientists estimate that there are some 15,000 glaciers nested within the Himalayan mountain chain forming the main repository for fresh water in that part of the world. The total area of glaciers in the Tibetan Plateau is expected to shrink by 80 percent by the year 2030.

The work is supported in part by the National Science Foundation.

Working on the project along with Thompson were Yao Tandong, Institute for Tibetan Plateau Research, Chinese Academy of Sciences; Ellen Mosley-Thompson, professor of geography at Ohio State and research scientist at the Byrd Center; Mary E. Davis, a research associate with the Byrd Center; doctoral student Natalie M. Kehrwald; Jürg Beer, Swiss Federal Institute of Aquatic Science and Technology; Ulrich Schotterer, University of Bern; and Vasily Alfimov, Paul Scherrer Institute and ETH in Zurich.

Western Canada’s Glaciers Hit 7000-Year Low

Overlord Glacier - 7000 years old. glacier in background.
Overlord Glacier – 7000 years old. glacier in background.

Tree stumps at the feet of Western Canadian glaciers are providing new insights into the accelerated rates at which the rivers of ice have been shrinking due to human-aided global warming.

Geologist Johannes Koch of The College of Wooster found the deceptively fresh and intact tree stumps beside the retreating glaciers of Garibaldi Provincial Park, about 40 miles (60 km) north of Vancouver, British Columbia. What he wanted to know was how long ago the glaciers made their first forays into a long-lost forest to kill the trees and bury them under ice.

To find out, Koch radiocarbon-dated wood from the stumps to see how long they have been in cold storage. The result was a surprising 7000 years.

“The stumps were in very good condition sometimes with bark preserved,” said Koch, who conducted the work as part of his doctoral thesis at Simon Fraser University in Burnaby, British Columbia. Koch will present his results on Wednesday, 31 October 2007, at the Geological Society of America Annual Meeting in Denver.

The pristine condition of the wood, he said, can best be explained by the stumps having spent all of the last seven millennia under tens to hundreds of meters of ice. All stumps were still rooted to their original soil and location.

“Thus they really indicate when the glaciers overrode them, and their kill date gives the age of the glacier advance,” Koch explained. They also give us a span of time during which the glaciers have always been larger than they were 7000 years ago — until the recently warming climate released the stumps from their icy tombs.

Koch compared the kill dates of the trees in the southern and northern Coast Mountains of British Columbia and those in the mid- and southern Rocky Mountains in Canada to similar records from the Yukon Territory, the European Alps, New Zealand and South America. He also looked at the age of Oetzi, the prehistoric mummified alpine “Iceman” found at Niederjoch Glacier, and similarly well-preserved wood from glaciers and snowfields in Scandinavia.

The radiocarbon dates seem to be the same around the world, according to Koch. It’s important to note that there have been many advances and retreats of these glaciers over the past 7000 years, but no retreats that have pushed them back so far upstream as to expose these trees.

The age of the tree stumps gives new emphasis to the well-documented “before” and “after” photographs of retreating glaciers during the 20th century.

“It seems like an unprecedented change in a short amount of time,” Koch said. “From this work and many other studies looking at forcings of the climate system, one has to turn away from natural ones alone to explain this dramatic change of the past 150 years.”

Researchers monitor glaciers for long-haul study

Michael O'Neal, an assistant professor of geography at the University of Delaware, and his students spent two weeks in August studying glaciers in the Cascade Mountain Range in the Pacific Northwest.
Michael O’Neal, an assistant professor of geography at UD, and his students spent two weeks in August studying glaciers in the Cascade Mountain Range in the Pacific Northwest.

Michael O’Neal, an assistant professor of geography at UD who recently returned from a two-week field trip studying glaciers in the Cascade Mountain Range, describes a typical day of research: A five-mile vertical hike kicks things off. Careful note-taking fills most of the daylight hours. The hike back to camp (at an elevation of 3,000 feet) completes the cycle. And at the end of the trip, the thoroughgoing data will be inconclusive. Two weeks in the life of millennia-old glaciers is a very short span, after all.

But O’Neal, who’s spearheading a decade-long study monitoring glaciers in the Pacific Northwest, isn’t motivated by instant results. In fact, it’s the monumental challenge and scale of the systems he studies, he says, that he enjoys.

“There are as many as 10,000 glaciers in the Cascades region,” O’Neal said, “and realizing that as one person I can only study a few, or a few dozen, in my lifetime makes it a trick.

“A lot of time is spent trying to figure out exactly where the glaciers that you’re studying were in recent history–primarily the last 200 years,” he added, describing the nature of the fieldwork that he, two colleagues and 10 students from UD’s Department of Geography conducted on the Aug. 12-21 trip. “And that’s no easy task.

“For the last 10,000 years, alpine glaciers in the mid latitudes in the northern hemisphere have fluctuated back and forth,” he said, “and what we’re studying now are how changes in precipitation and temperatures over a span of years are affecting the larger valley glaciers in the region.”

Starting from the Canadian border and ending in Oregon, O’Neal’s August expedition with Brian Hanson, glaciologist and chairperson of UD’s Department of Geography; Daniel Leathers, climatologist and professor of geography at UD; and seven UD graduate and three undergraduate students, included visits to some of the larger valley glaciers in the Cascade range and tracked data being charted for the 10-year study.

Now in its second year, the monitoring process will include summertime field trips to Iceland, Greenland, Alsaka and the Canadian Rockies, as well, and will trace how patterns in precipitation and temperature affect glaciers over time.

“One of the things that the Department of Geography specializes in is especially cold climates, so in this study we’re trying to understand how glaciers vary naturally, and we’re particularly interested in recent glacier fluctuation in the Cascades,” O’Neal said. “We’re one of just a handful of groups working in that area of the country, so that makes the region all the more appealing.”

Adding that the study, at its conclusion, will leave some room for the growing debate over global warming, O’Neal emphasized that the primary goal is to better understand the natural variations of glaciers over time.

“Everybody has heard that glaciers are retreating,” he said, “and in a general sense that’s true. But understanding how much glaciers have retreated and when and how they have retreated is very difficult, and the data is very complex. In our fieldwork, we’re trying to understand how glaciers vary naturally. Glaciologists have observed–just in recent history–that these systems can advance by as much as 300 meters in a very short span of years, as they did in the 1980s. So knowing how and why they do this is vital for making any sweeping predictions of climate change.”

Given this scholarly angle, as well as the leisurely timeframe, the study, O’Neal said, allows for in-depth research and affords students the rare opportunity to take what they’ve learned beyond the classroom.

“If I’m excited about one thing, it’s that students from our department are getting the opportunity to do something they’d probably never do on their own,” he said. “We camp at about 3,000 feet and hike every day to about 7,000 or 8,000 feet. Students get exposed to icy, alpine landscapes, and getting to these locations is no small feat. It’s a physical challenge to study them on top of a mental challenge, and students get a real vision of what it means to be in these environments and why it’s so hard to study them. At the end of two weeks, there are enough scrapes and bruises for me to be glad that I’ve limited the trip to 10 days and 10 students, but the value of the experience is lasting.”

Two independent projects, launched during the summer’s trip, reflect this. One, by master’s candidate Adam Goldstein, a geology major from Wayne, N.J., will examine how heavy deforestation affects local summertime mountain temperatures (and, by extension, glaciers). The other, by senior Janine Howard, an environmental conservation major from Ridgefield, Conn., will draw on data she collected this summer for a presentation she’ll give with O’Neal at the annual conference of the Association of American Geographers in Boston next spring.

“Geography students at UD do work on ice and climate, so being involved in fieldwork is important for them, and in terms of their collaboration, we’re going to look for National Science Foundation funding,” O’Neal said.

Explaining the complex and long-term nature of the study, he added that most students who want to participate in the summertime field trips get the chance.

“There are warm periods, not unlike the one we’re in now, that have occurred frequently on 100-year time scales during the last 10,000 years,” O’Neal said, “and part of what we want to understand is how often they occurred and how many times in the past few thousand years glaciers retreated to their farthest extent. That is the kind of information we are trying to establish even before we try to tweak out how recent patterns of precipitation and temperature have affected glaciers in the Cascades.”

Fitting data collected from the study into a larger framework of glacier research is an even bigger goal, he added.

“The Pacific Northwest is a small region of the planet, and relating our data to research conducted in other regions–there are tens of thousands of glaciers on earth–will be tricky,” O’Neal said.

“One of the things we do believe–and one of the reasons we are studying glaciers in the Pacific Northwest, where there are decades-old precipitation patterns that last–is that precipitation and temperature are equally important in affecting the larger valley glaciers in the Cascade Range. In a lot of regions, that’s not true. But in the Pacific Northwest, the precipitation patterns tell at least half the story on how the glaciers out there behave. So the statement we can make from our research that hasn’t been made before is that understanding the role precipitation plays on glaciers in Cascades region is critical,” he said.

As a larger framework gets laid and the science community draws further evidence for global warming, O’Neal said that having conclusive data will be especially useful.

“I think that most of the people in this department would agree that if you look at the statistics of recent climate, the planet does seem to be warming,” he said. “But climate is the statistics of weather, and weather is noisy, and glaciers are poor proxies of climate change in general. They take a long time to respond. Their behavior is complicated and the natural variations of the systems are poorly understood. So while we hope that we’re a contributor to the global thought that global warming is affecting glaciers, we are really gathering data with the intent that it will go to the scientific community to give us all better tools for understanding the natural variations of glacial systems.”

Climate research gives clues to human expansion out of tropical Africa

New research that involves a University of Nebraska-Lincoln scientist has shed light on an important, but previously little-understood period in Africa’s climate history that has implications for understanding human evolution and the expansion of Homo sapiens out of tropical Africa.

In a paper published this week in the online version of the Proceedings of the National Academy of Sciences, a team headed by Andrew Cohen of the University Arizona and including UNL’s Jeffery Stone as the second author, reported findings from sediment cores recovered from one of the world’s deepest lakes, Lake Malawi in East Africa’s Great Rift Valley. Cohen, Stone and colleagues reported finding evidence of two extended periods of extreme aridity between 135,000 and 70,000 years ago, an important time in human pre-history.

“Prior to this research, there was not a really good terrestrial record of climate that stretched back through the period of human development and migration from the tropical region of Africa,” said Stone, an adjunct faculty member in the UNL Department of Geosciences who also has a research appointment at Arizona.

“Most of the previous records basically stretch back to the last glacial maximum, maybe 20,000 years. They show some really dry conditions and it’s assumed that that had a huge impact on human populations in Africa, but nobody really had a sense of what was going on before that.”

The scientists studied a variety of fossils and other sediments that settled to the lake bottom over the millennia and used them as proxies to interpret the climate at various times during the last 140,000 years. For example, diatoms, Stone’s specialty, are one-celled organisms having a silica skeleton that fossilizes readily. Different species of diatoms flourish or fail during different climatic conditions, so their relative abundance or absence provides a good indication of contemporary climate conditions.

What the diatoms and other proxies indicate is a Lake Malawi basin between 135,000 and 70,000 years ago that looked a lot different from the lush conditions found there today. Modern Lake Malawi has a surface area of 29,500 square kilometers (more than 11,000 square miles) and reaches a depth of 706 meters (more than 2,300 feet). Annual rainfall in its watershed varies from 800 to 2,400 millimeters a year (31-93 inches; for comparison, Lincoln averages 27.8 inches of rainfall per year).

But records from the sediment cores reveal two periods of megadrought, from 135,000 to 127,000 and 115,000 to 95,000 years ago, when the level of Lake Malawi fell 550 to 600 meters (1,800-1,970 feet) below present-day levels. The surrounding watershed was a semidesert that received less than 400 millimeters (16 inches) of rain per year, creating much drier conditions than occurred during the last glacial maximum, 35,000 to 15,000 years ago, when Lake Malawi’s level fell by only 30 to 200 meters.

There is little archaeological evidence of human habitation in tropical Africa during the megadroughts, a period that coincides with the earliest evidence of humans outside the region — about 125,000 years ago in North Africa and the Middle East.

The research by Stone and colleagues, however, indicates that tropical Africa’s climate became wetter after 70,000 years ago and reached conditions comparable to today by about 60,000 years ago. That period coincided with increased evidence of human habitation in the area, and closely coincided with increased aridity in other parts of the continent.

Cohen said the new finding provides an ecological explanation for the “Out-of-Africa” hypothesis that suggests that all humans descended from just a few people living in Africa sometime between 150,000 and 70,000 years ago. He said it’s possible that the human population crashed during the megadroughts, but rebounded when the climate became more hospitable. The growing human population eventually expanded down the Nile valley and dispersed around the globe.

The PNAS paper concluded that this timing is “consistent with the idea that the earlier (approximately 125,000 years ago) documented occurrence of modern humans in North Africa and the Levant represents ultimately unsuccessful ‘excursions’ out of Africa.”

The article is scheduled for publication in the Oct. 16 print edition of PNAS. The National Science Foundation, the International Continental Drilling Program and the Smithsonian Institution funded the research.

Scientist tracks greenland meltwater

Many glaciologists believe that snow/ice melt in Greenland could equate to a 1 meter increase in ocean levels, something that would be devastating to a major portion of the human population
Many glaciologists believe that snow/ice melt in Greenland could equate to a 1 meter increase in ocean levels, something that would be devastating to a major portion of the human population

World oceans would rise 23 feet and flood many coastal areas if climate change melted the entire Greenland ice cap. And satellite images from 1980 onward reveal the surface of this vast ice sheet is warming, getting soggy and staying wet for longer periods every year.

However, preliminary research by The University of Montana and its partners suggests some of this meltwater does not reach the ocean to contribute to sea-level rise. Instead it infiltrates downward into colder snow and refreezes into ice layers that can be more than a foot thick. These layers are fragmented, so water can’t flow atop them for long before draining downward again and freezing in place.

“We are still working up our results, but so far this is good news concerning worries about Greenland’s role in the sea level rise we see happening today,” said UM glaciologist Joel Harper. “Since many of the ice layers that form during a year of heavy melt are discontinuous, the next year’s melt can’t travel along the ice layers as a means of escaping the ice sheet.”

He said it’s so dark and cold during Greenland winters that even with some winter warming the snowpack is still extremely cold going into summer, “and summer melting always will have a hard time warming a snowpack laden with cold dense ice layers.”

Harper was part of a six-person scientific expedition that ventured onto the Greenland ice sheet for a month during June and July. They lived in tents high atop the ice cap at about 6,600 feet in a white, featureless landscape swept by endless wind. To do its work, the group made 60- to 70-mile journeys down into the melt zone closer to Greenland’s west coast, using snowmobiles to pull scientific gear and expedition members on skis.

Harper said their research was funded by a $524,000 National Science Foundation grant. His project collaborators are Tad Pfeffer of the University of Colorado and Neil Humphrey of the University of Wyoming. Each scientist brought one graduate student to complete the team.

The researchers drilled 21 35-foot-long ice cores during the course of their work. They also dug many snow pits and did numerous experiments with colored dye to track meltwater flow. In addition, they installed two meteorological stations and used radar to map ice layers beneath the snow.

In five boreholes located in sequentially lower elevations across a 25-mile span, the team also installed vertical strings of temperature sensors to note melting and freezing events in the snow up to 35 feet deep. (When water freezes it releases heat – a thermal signature that can be detected.) Harper said the sensors – called thermisters – have their own power source and will record data until researchers retrieve them next year.

He compared the Greenland ice cap to pancake batter. In its middle at higher elevations there is more snowfall than melting. As more snow is poured on, it compresses the vast sheet, which flows outward toward the warmer coasts where there is more melting.

The team had two snowmobiles to haul six people and their gear down to the melt zones to do their research. The landscape is utterly devoid of landmarks, so they used global positioning systems to navigate during the three-hour traverses. Two scientists drove, while the rest were towed behind the snowmobiles on skis.

“While skiing, we put on every bit of clothing we had and an iPod because you were standing behind these snowmobiles for three hours or more,” Harper said. “We would use a bike tire as a harness clipped to the rope. So we would just stand there and try not to fall asleep as we were pulled along.”

Harper, who was a competitive skier as a youth in Colorado, also tried using a sail to kite ski across the ice cap. His power source was Greenland’s endless katabatic winds, which are caused by dense cold air atop the ice sheet flowing downward toward the warmer coasts.

“A lot of times it was too windy – you could get up to 30 mph no problem,” he said. “I could get screaming along – and I’m used to speed – but this was on the edge. I found it was too hard to navigate long distances with GPS when you are trying to fly the kite and not crash. It just wasn’t compatible with the whole group, so in the end it was more for fun.”

He said some of the melt zone contained barely wet snow, while others areas were a “slush swamp” of super-saturated snow that a person without skis could sink into like quicksand. The expedition had to make the long traverses from base camp because members didn’t dare camp in the melt zone. Too much thawing could bog down their snowmobiles and leave the researchers stranded in an area where ski planes can’t land. They might be stranded in the soggy snow until the next freeze.

“And if the snow machines would break, you couldn’t possibly ski back in a day,” he said. “It’s too far.”

Harper said his group will return next year to study another 75-mile stretch of the ice cap. They will start at the lowest elevation examined last summer and continue downward toward the coastal melt zone. The expedition will begin earlier in the year so the snow won’t be as treacherous at lower elevations.

“This is one reason why our results are preliminary,” he said. “We only have half the story. I suspect things might really be moving down below, but so far in the upper part of the ice sheet, we have thrown that out. In that area we found the melt is increasing every year, but it isn’t going anywhere.”

Harper said they decided to study the west side of the ice cap because it is accessible from the town of Kangerlussuaq, which is the logistics headquarters for science in Greenland. The ice they studied also is the headwaters of Jakobshavn, one of Greenland’s big calving glaciers that has increased speed in recent years. Their base camp was a three-hour plane ride from Kangerlussuaq.

“There was nothing special about our camp,” he said. “It was just some GPS coordinates we selected in the middle of nowhere. We got nailed by a big storm right after we arrived, but after that temperatures stayed between about 10 and 35 degrees Fahrenheit.”

Harper said their work might partially explain why Greenland isn’t a larger player in current sea-level rises despite its enormous ice cap. A 2007 article in the journal Science contends Greenland contributes about 0.5 millimeter to ocean level rise annually, while smaller glaciers scattered around the globe contribute 1.1 millimeter to sea-level rise.

“Other recent work shows that ice loss from small glaciers and ice caps like those in Montana dominate current sea-level rise and will likely continue to dominate sea-level increases for at least the next 50 years,” he said. “Since there are several hundred thousand small glaciers around the world, the sea-level rise we expect from them is still very significant.

“I don’t know of any glaciologist who thinks anything like a 6-meter (19.8 foot) sea-level rise is in the cards by the end of the century,” Harper said, “but even 1 meter – which is at the upper end of what we currently think might be possible – would be a very big deal.”

Glaciologist Looks To Ice For Clues About Global Warming

Glaciologists extract ice cores, analyze them and determine changes in climate over time.
Glaciologists extract ice cores, analyze them and determine changes in climate over time.

Once or twice a year Keith Mountain, chair of the Department of Geography and Geosciences at the University of Louisville, and colleagues from the Byrd Polar Research Center at Ohio State University spend months hunting for a disappearing treasure: ice.

They travel to a glacier in the mountains of Bolivia, Peru, China, Antarctica or Tanzania. The conditions can be brutal at elevations as high as 20,000 feet, but what they find might help save the planet.

Glacier ice contains thousands of years of the Earth’s climate history. It also provides clues as to how and why global warming is happening today, Mountain said.

The researchers use a portable drilling system to extract from the glaciers cylindrical ice cores about 13 centimeters in diameter and hundreds of meters long. They cut each core into 1-meter segments, then mark and pack it for later analyses.

Like the rings of trees, these ice cores are time capsules which can span tens of thousands of years.

Through mathematical models and other methods, including preliminary test drillings, the team can determine the amount of ice compression and come up with reliable ways to interpret these ice cores, he explained.

“We can reconstruct atmospheric temperatures and ascertain precipitation rates and how much dust there was in the atmosphere,” Mountain said. “We can find out the chemical composition of the atmosphere. You can pick up things like various nitrates-sea salt, for example-and figure out wind directions and the sources of moisture and how those may have changed over time.”

The team has determined from interpreting the ice records over time that, “yes, climate change is global and real,” he said.

Rising temperatures worldwide and local decreases in precipitation are contributing to the decline of the glaciers — which makes their work a race against time.

“When I started out in this field in the late ’70s I never would have thought that the photographs we took of this big ice sheet in southern Peru would become archival records of something lost,” Mountain said. “We photograph the changes there every year now, and the changes are occurring quickly. It’s retreating on the order of 50 meters a year.”

Ice is retreating not only in Peru, but worldwide. The famed white cap of Mt. Kilimanjaro in Tanzania soon will be no more. At its current rate of melting, he said, it will disappear by about 2015.

Glaciologists are just one scientific sector contributing to the mass of evidence on the reality of global climate change, Mountain said, noting that 95 percent of the scientific community believes that global climate change is happening and that humans are a significant causal factor.

Yet somehow, he said, a 95 to 5 percent ratio becomes a yes-no, either-or vote: “Some are trying to turn this into a debate, but there is no debate.”

In his native Australia where years of drought have led to bush fires and dying cattle, global warming is a real issue, Mountain said. That’s also true in other parts of the world.

“For the people in Peru, as the glaciers melt they are losing their irrigation water for farming. In Tibet, as the glaciers recede streams are evaporating and leaving big salt deposits that make the remaining water undrinkable,” he said.

The jury is no longer out on global warming, Mountain said.

“At some point, the jury has to come back and make a decision. What kind of policies are we going to develop to deal with this?”

Glaciers and Ice Caps to Dominate Sea Level Rise Through 21st Century

When a glacier with its “toe in the water” thins, a larger fraction of its weight is supported by water and it slides faster and calves more ice into the ocean at the glacier terminus. – Photo Credit: Nicolle Rager Fuller, National Science Foundation

Ice loss from glaciers and ice caps is expected to cause more global sea rise during this century than the massive Greenland and Antarctic ice sheets, according to a new University of Colorado at Boulder study.

The researcher, primarily funded by the National Science Foundation (NSF) and NASA, concluded that glaciers and ice caps are currently contributing about 60 percent of the world’s ice to the oceans and the rate has been markedly accelerating in the past decade, said Emeritus Professor Mark Meier of CU-Boulder’s Institute of Arctic and Alpine Research, lead study author. The contribution is presently about 100 cubic miles of ice annually — a volume nearly equal to the water in Lake Erie — and is rising by about three cubic miles per year.

In contrast, the CU-Boulder team estimated Greenland is now contributing about 28 percent of the total global sea rise from ice loss and Antarctica is contributing about 12 percent. Greenland is not expected to catch up to glaciers and ice caps in terms of sea level rise contributions until the end of the century, according to the study.

A paper on the subject appears in the July 19 issue of Science Express, the online edition of Science magazine. Co-authors include CU-Boulder INSTAAR researchers Mark Dyurgerov, Ursula Rick, Shad O’Neel, Tad Pfeffer, Robert Anderson and Suzanne Anderson, as well as Russian Academy of Sciences scientist Andrey Glazovsky.

“One reason for this study is the widely held view that the Greenland and Antarctic ice sheets will be the principal causes of sea-level rise,” said Meier, former INSTAAR director and professor in geological sciences. “But we show that it is the glaciers and ice caps, not the two large ice sheets, that will be the big players in sea rise for at least the next few generations.”

The accelerating contribution of glaciers and ice caps is due in part to rapid changes in the flow of tidewater glaciers that discharge icebergs directly into the ocean, said the study. Many tidewater glaciers are undergoing rapid thinning, stretching and retreat, which causes them to speed up and deliver increased amounts of ice into the world’s oceans, said CU-Boulder geology Professor Robert Anderson, study co-author.

Water controls how rapidly glaciers slide along their beds, said Anderson. When a glacier with its “toe in the water” thins, a larger fraction of its weight is supported by water and it slides faster and calves more ice into the ocean at the glacier terminus.

“While this is a dynamic, complex process and does not seem to be a direct result of climate warming, it is likely that climate acts as a trigger to set off this dramatic response,” said Anderson, also an INSTAAR researcher.

The human impact of this accelerated sea level rise could be dramatic. The team estimated accelerating melt of glaciers and ice caps could add from 4 inches to 9.5 inches of additional sea level rise globally by 2100. This does not include the expansion of warming ocean water, which could potentially double those numbers. A one-foot sea-level rise typically causes a shoreline retreat of 100 feet or more. The World Bank estimates that about 100 million people now live within about three feet of sea level.

“At the very least, our projections indicate that future sea-level rise may be larger than anticipated, and that the component due to glaciers and ice caps will continue to be substantial,” wrote the researchers in Science Express.

The team summarized satellite, aircraft and ground-based data from glaciers, ice caps, the Greenland ice sheet, the West Antarctic ice sheet and the East Antarctic ice sheet to calculate present and future rates of ice loss for the study.

Meier estimated there are several hundred thousand small glaciers and small, pancake-shaped ice caps in polar and temperate regions. They range from modest, high mountain glaciers to huge glaciers like the Bering Glacier in Alaska, which measures about 5,000 square miles in area and is nearly one-half mile thick in places.

The researchers used a mathematical “scaling” process to estimate more remote glacier volumes, thicknesses and trends by factoring in data like altitude, climate and geography. They used data gathered from around the world, including cold regions in Russia, Europe, China, Central Asia, Canada and South America.

While warming temperatures will likely cause many small high mountain glaciers in North America Europe to disappear by the end of the century, large ice fields and ice caps will continue to produce large amounts of melt water, Meier said. The scientists also believe many “cold” polar glaciers and ice caps will soon warm up enough to begin melting and contributing to sea rise.

The retreat of the Greenland and Antarctic ice sheets also is giving birth to new, smaller glaciers that are prime candidates for study by scientists. “It is incorrect to assume that the small glaciers will simply go away next century — they will continue to play a key role in the sea level story,” said Anderson.

Anderson also said that although the volume of ice locked up in Greenland is equal to roughly 23 feet in sea rise, only a small fraction is likely to be “pulled out” during the next century, most of it through outlet glaciers.

Many smaller “benchmark” glaciers around the world that have been under study for decades are expected to disappear by the end of the century, said Anderson. “We need to start gathering benchmark information on some of the larger glaciers that are unlikely to disappear, so that we can have a long-term record of their behavior.”

Anderson said outlet glaciers in Greenland behave much like tidewater glaciers in Canada and Alaska, making them very relevant for long-term study. “Since the world is becoming increasingly aware that sea-level rise is a very real problem, we need to acknowledge the role of all of the ice masses and understand the physical mechanisms by which they deliver water to the sea.”