posted 03-27-2002 02:09 AM               

Tuesday, 26 March, 2002, 16:18 GMT
Arctic ice 'melting from below'
By Alex Kirby BBC News Online environment correspondent

Scientists believe they have identified a mechanism which can explain the thinning of the Arctic sea ice. They say the thinning, which in summer reaches more than 40% in some areas, has two causes. Rising air temperatures, possibly the consequence of global warming, are melting the ice from above. And warmer water is also rising from the depths to attack the ice from below.

Professor Peter Wadhams, of the Scott Polar Research Institute in Cambridge, UK, said in 2000 that he had established the degree of thinning using measurements from submarines in 1976 and 1996. He said these showed that in that time a large area of the sea ice, stretching from the North Pole to the Fram Strait between Svalbard and Greenland, had thinned by 43% during the Arctic summer. US data from the other side of the Arctic, between the Pole and the Bering Strait, found a similar thinning over the same period. The reported melting has been questioned by scientists who say the ice may not be missing, but simply concentrated in areas where it has not been found. But Professor Wadhams says the thinning he has detected, from 16ft (4.8m) 20 years ago to 9ft (2.7m) today, is scientifically explicable.

He told BBC News Online: "People say global warming can't be raising air temperatures enough to melt the ice, because the Arctic winter temperature is around -30C anyway, and a one-degree warming would be irrelevant. "But it's the summer temperatures that matter. Arctic summers are getting longer, so there is longer for the warmer air to melt the snow and affect the ice beneath. "The other mechanism is the warming of one or two degrees in the water under the ice - enough to increase the bottom melting quite considerably. "There is a cold water layer immediately beneath the ice. But that's changing its stability and salinity, because of changes in the distribution of Siberian river water in the Arctic. Shippers' bonanza "Over a large area that cold water is becoming more saline and denser, which means it's letting more heat rise through it."

Professor Wadhams thinks the Arctic could be virtually ice-free during the summer by about 2080. He told BBC News Online: "The north-east passage across the top of Siberia is already close to becoming commercially viable. "It will shorten the existing route from Europe to the Far East by about 40%, from 20,000 km (11,000 nautical miles) to 13,000 km (7,000 nm). "Containers going from Germany to Japan on Russian vessels are now using that route experimentally. There'll be huge savings for shipping. "And as the route lies through Russia's territorial waters, it will collect fees for providing ice breakers, search and rescue services and so on." Threat from the south But for wildlife the prospects are less good. Polar bears are likely to face problems as the sea ice retreats and makes it harder for them to hunt the seals on which they depend.

posted 03-27-2002 02:28 AM               

Earth Institute News
posted 03/01/01 2:0O P.M. EST

Evidence of Recent Volcanic Activity Found Along the Slow-Spreading Gakkel Ridge
By Kristen Watson
Palisades, N.Y.

Researchers working under the ice canopy in the Arctic Basin, the last of Earth's oceanic frontiers, have confirmed that volcanoes and other tectonic processes often accompany seafloor spreading along the global mid-ocean ridge (MOR) system.

A team of researchers from Columbia, the University of Hawaii at Manoa and Tulane collected data along the Gakkel Ridge, the Earth's slowest spreading MOR, which was thought to be non-volcanic. Data was acquired using mapping sonars developed by Columbia researchers attached to a nuclear-powered submarine. Bathymetric data and sidescan images of the ultra-slow spreading (approximately one centimeter per year) eastern Gakkel Ridge depict two young volcanoes covering approximately 447 square miles of the seafloor. The location of the western volcano is the site of close to 250 teleseismic events detected in 1999. The data demonstrate that eruptions along the ridge are larger and more frequent than previously theorized. "I first noticed the existence of an unusual seismic swarm on the Gakkel Ridge back in the summer of 1999," said Maya Tolstoy, an associate research scientist at Columbia's Lamont-Doherty Earth Observatory. "It looked classically volcanic."

Tolstoy researched how to confirm the presence of volcanism in this area. Eventually, she realized she did not have to go far to validate her theory. Dale Chayes, one of Tolstoy's Lamont-Doherty colleagues, had collected bathymetry and sidescan image data of the Gakkel Ridge using an underwater mapping system he developed for science ice exercises (SCICEX), a program run by the U.S. Navy and National Science Foundation. The program used nuclear-powered Sturgeon class submarines to study the ice canopy, oceanography, biology and geology of the Arctic Basin. With permanent pack ice covering the Arctic Ocean, scientists cannot depend on the usual sea-going vessels or satellites to map the ocean floor, making nuclear submarines the optimal tools for Arctic research.

Columbia Equipment Shines Light on Darkened Seas

For SCICEX-98 and SCICEX-99, the U.S. Navy's submarine USS Hawkbill (SSN 666) was equipped with seafloor characterization and mapping pods (SCAMP), the geophysical mapping system built by Chayes' team of engineers to create the first high-quality, systematic three-dimensional maps of the Arctic seafloor. "SCAMP is composed of a sidescan swath bathymetric sonar (SSBS), a high-resolution subbottom profiler (HRSP), a Bell BGM-3 gravity meter and a data acquisi tion and quality control system (DAQCS)," said Chayes. "The SSBS collects data across a swath of seafloor as much as seven times the water depth perpendicular to the submarine's track.

This data can be used to construct a digital terrain model of the shape of the seafloor and the water depth, or to construct an image of the reflectivity of the seafloor that is similar to an aerial photograph. The HRSP emits sound that penetrates as much as 600 feet into the seafloor below the submarine and from this data images of the sediment layers can be constructed."

posted 03-27-2002 04:12 AM               

Stanford Report, January 16, 2002
Antarctic mud reveals ancient evidence of global climate change BY MARK SHWARTZ

Scientists concerned about global warming are especially troubled by dramatic signs of climate change in Antarctica -- from rapidly melting glaciers to unexplained declines in penguin populations. Records show that average winter temperatures today are 10 degrees higher in parts of Antarctica than 50 years ago. If that warming trend continues, say many climate experts, the vast Antarctic ice sheets could melt, causing catastrophic coastal flooding as the world's oceans rise.

Ironically, say researchers, the most pristine continent on Earth is heating up primarily because of increased greenhouse gas emissions from cars, power plants and other human endeavors elsewhere on the planet. But new geologic evidence unearthed from deep-sea mud deposits strongly suggests that Antarctica experienced periods of extreme warming and cooling long before the invention of the automobile.

"We've got a sedimentary record that reveals very significant changes in water temperature and ice melt during the past 7,000 years," said Robert Dunbar, professor of geological and environmental sciences. "The cause of these highly variable climate changes is still a mystery." Glacial evolution Dunbar and Boston University collaborators Richard W. Murray and Kelly A. Kryc presented their findings at the annual meeting of the American Geophysical Union (AGU) in San Francisco on Dec. 14 during a session titled "Antarctic Glacial Evolution: The Marine Geologic Record II."

The researchers based their study on a biogeochemical analysis of sediments obtained during a recent cruise of the JOIDES Resolution, a research vessel operated by the Ocean Drilling Program (ODP) -- an international project dedicated to exploring the geological history and evolution of the Earth. ODP is principally funded by the National Science Foundation with additional support from institutions representing nearly two dozen other countries, including Germany, Japan and Australia. In 1998, ODP scientists extracted a 150-foot-long sediment core from the muddy bottom of the Palmer Deep -- a submerged section of the continental shelf along the west Antarctic Peninsula about 3,000 feet below sea level.

The sediment sample was loaded with the shells of microscopic creatures called diatoms dating back some 10,000 years to the beginning of the Holocene -- the most recent geologic epoch. "The Antarctic Peninsula is an ideal region to investigate climate change at decadal to millennial time scales due to its location in one of the Earth's most dynamic climate systems," noted Dunbar. "The ODP sample gives us the first continuous, high-resolution Holocene sediment record from the Antarctic continental margin." The sediment sample revealed higher concentrations of diatom shells during the mid-Holocene, roughly 5,500 to 7,000 years ago, which indicates that the waters surrounding the Antarctic Peninsula were more biologically productive then. According to Dunbar, higher productivity suggests that sea ice was less abundant during the mid-Holocene -- a further indication that temperatures were higher. "We think it was quite a bit warmer then," he observed, noting that geochemical analysis of the sediment also revealed higher levels of nitrogen during the mid-Holocene. "Warmer temperatures may have produced freshwater streams that fed nitrogen and other nutrients into coastal waters," he explained. Climate surprises Further analysis revealed other surprises.

According to the researchers, Western Antarctica appears to have undergone periods of warming and cooling during the mid-Holocene -- regular cycles lasting 400, 200, 140 and 70 years. "We believe these cycles of warming and cooling may have been caused by variations in the amount of energy emitted by the sun," said Dunbar, noting that solar activity routinely increases and decreases on a predictable 11-year cycle. There may be other explanations for these ancient periods of cooling and warming, he added, but one fact is certain: They were not caused by people. However, Dunbar was careful to point out that, while increased solar activity may be influencing climate change today, it is a separate phenomenon from the greenhouse effect, which is largely attributed to human-induced carbon dioxide emissions.
http://www.stanford.edu/dept/news/report/news/january16/agudunbarscitech-116.html

Geophysical Evidence of Holocene and Active Tectonism and Volcanic Activity Beneath the Ross Sea Continental Shelf, the Ross Ice Shelf, and the West Antarctic Ice Sheet

John C. Behrendt
Institute of Arctic and Alpine Research University of Colorado, Boulder, CO 80309-0450, USA behrendj@stripe.colorado.edu; also, U.S.Geological Survey, Denver

There are more than 100 exposed late Cenozoic alkaline volcanoes throughout the West Antarctic rift system interpreted as caused by a mantle plume. A few widely scattered volcanoes are active and volcanic activity can be expected throughout (LeMasurier, 1990).

Marine multichannel seismic reflection, and aerogeophysical surveys since 1984 over the West Antarctic rift system have shown evidence of neotectonic activity. Microseismicity has been reported from the Victoria Land Basin beneath the Ross Sea continental shelf and a magnitude 5.3 earthquake in 1993 beneath the continental shelf about 150 km east of Cape Hallett attests to active tectonism in the area. Holocene fault scarps observed on high resolution seismic reflection profiles in the western part of the Victoria Land basin indicate reactivation of basin bounding faults as old as late Cretaceous defined by deep reflection profiles. Probably deglaciation of the Ross Sea continental shelf since about 10 Ka triggered higher levels of seismicity than at present as has been reported offshore Norway since deglaciation there.

Aeromagnetic surveys over the Ross Sea continental shelf and Ross Ice Shelf show >100 short wavelength anomalies interpreted as caused by shallow source late Cenozoic volcanic centers which have penetrated the sedimentary section of the Victoria Land basin and surrounding area. Eight of these aeromagnetic anomalies are also crossed by marine seismic and magnetic gradiometer profiles, which confirmed this interpretation. Two of these volcanic centers have probable hyaloclastite edifices which have been interpreted as evidence of Holocene age.

Aeromagnetic and radar ice sounding surveys reported over the West Antarctic Ice Sheet (WAIS) show hundreds of magnetic anomalies interpreted as having late Cenozoic volcanic sources at the base of the ice. One has been interpreted as an active volcano (Mt. CASERTZ) based on a 600-m high edifice and collapse of the overlying snow surface (Blankenship et al., 1993). The great majority of subglacially erupted inferred hyaloclastite volcanic edifices have been eroded as they were injected into the moving ice.

I interpret these various lines of geophysical evidence as indicating that the West Antarctic rift system is still alive, although possibly at its last gasp.

li nk

Volcanic activity in Antarctica is limited to only a few places, the most notable being Mount Erebus on Ross Island. The island is entirely of volcanic origin, as are White and Black Islands, Brown Peninsula and Mina Bluff, and the massifs of Mounts Discovery and Morning. These are products of eruptions--from the Pliocene through the present--of basaltic lavas from central cones and fissures at various locations. Mount Erebus is the largest and by far the most active of the few volcanoes on the continent, almost continuously spewing out steam and gases from its summit crater.
http://www.antarcticconnection.com/antarctic/science/geology.shtml

Recent Activity:

posted 05-09-2002 12:40 PM               

Thu May 9,11:26 AM ET

WASHINGTON - An iceberg 47 miles (75.2 kilometer) long and 4.6 miles (7 kilometers) across has broken off the Ross Ice Shelf in the Antarctic, the National Ice Center reported Thursday,

The giant sheet of glacial ice and snow was named C-18, meaning that it's the 18th iceberg to be tracked in that section of Antarctica since 1976, when record keeping began.

The iceberg, floating close to the ice shelf, is not considered a hazard to navigation. It was spotted on satellite images.

The National Ice Center provides worldwide ice analyses and tracking to assist the military and private shippers.
It is a joint operation of the Navy, National Oceanic and Atmospheric Administration and Coast Guard.
http://story.news.yahoo.com/news?tmpl=story&u=/ap/20020509/ap_wo_en_ge/us_new_iceberg_1&printer=1

posted 05-22-2002 06:26 PM               

By Randolph E. Schmid
Associated Press Writer
Tuesday, May 21, 2002; 6:16 PM

WASHINGTON –– Another new iceberg has broken away from Antarctica, the National Ice Center reported Tuesday.

The berg named D-17 broke off from the Lazarev Ice Shelf, a large sheet of glacial ice and snow extending from the Antarctic mainland into the southeastern Weddell Sea.

The new iceberg is 34.5 miles long and 6.9 miles wide, about the same size as St. Lucia Island in the Caribbean Sea. It was observed on an image collected by the Defense Meteorological Satellite Program.

Icebergs are named for the area quadrant of Antarctica where they appear. D-17 is the 17th berg reported since record keeping began in 1976.

Just last week, an iceberg nearly as large as the Chesapeake Bay – called C-19 – broke away from Antarctica, where it is late summer.

In March, another giant berg broke free in an adjacent area. Named B-22, it measured 2,120 square miles, bigger than the state of Delaware. Also in March, a large floating ice shelf in Antarctica collapsed.

However, new measurements indicate the ice in parts of Antarctica is thickening, reversing earlier estimates that the sheet was melting.

Scientists reported in January that new flow measurements for the Ross ice streams indicate some of their movement has slowed or halted, allowing the ice to thicken. Researchers don't know if the thickening is merely part of some short-term fluctuation or represents a reversal of the ice's long retreat.

That report, in the journal Science, came less than a week after a paper in Nature reported that Antarctica's harsh desert valleys – long considered a bellwether for global climate change – have grown noticeably cooler since the mid-1980s.

posted 06-05-2002 01:09 PM               

Mysterious as the frozen continent may be, Antarctica is no different from any other landmass when it comes to the frequency of earthquakes, according to Penn State geoscientists.

Antarctica is a huge continent the size of the United States and Mexico combined. In the past, only a few seismic recording stations monitored earthquake activities in Antarctica, compared to the thousands of stations spread throughout the rest of the world. Consequently, the number of recorded earthquakes has always been thought to be paradoxically small, says Dr. Sridhar Anandakrishnan, associate professor of geosciences.

"It was thought that perhaps Antarctica was different," says Anandakrishnan. "That it did not have earthquakes because somehow the ice on top of the rock suppressed the earthquakes and that the cold temperatures also contributed.

"Now we have data to show that that is not true. We did find significant earthquakes in West Antarctica," he told attendees today (May 30) at the spring meeting of the American Geophysical Union in Washington, D.C.

Anandakrishnan, working with Paul Winberry, graduate student in geosciences, analyzed seismic activity from six seismic stations covering an area a little over 300 miles on a side. The research was supported by the National Science Foundation.

"West Antarctica is a rift, an area that is pulling apart and regions like that are prone to earthquakes," says Anandakrishnan. "We put listening posts in an area where we expected to have seismicity and we saw a fair number of events."

What the researchers found were a significant number of small earthquakes. While large earthquakes can be detected at seismic stations all around the world, smaller ones are only recordable locally.

Recording and gathering data from seismic equipment in West Antarctica is not easy. Equipment must be able to withstand and operate in the extreme climate of the ice sheet. For three months, the sun shines 24 hours a day and the temperatures are similar to a northern U.S. winter with highs of 5 degrees Fahrenheit. During this time, the seismic stations operate on solar power.

During the winter months, when the wind blows, wind generators charge the batteries that supply the power to heat the stations and operate the equipment.

"One station operated the whole year round," says Anandakrishnan. "All the rest operated all summer and from 60 to 80 percent of the remainder of the year."

But recording the data is not the only problem. While in other parts of the world, data can be sent via satellite from distant locales, in Antarctica researchers must return to the seismic stations to download the information. Satellites do not move in convenient orbits to relay information from the stations to the researchers at home.

"All of the satellites are in the northern hemisphere," says Anandakrishnan."We have to go back every year to collect the data."

The researchers hope that better satellite coverage of the southern hemisphere will help with future work in Antarctica. While electronics do not really mind the cold, all things mechanical are adversely affected by the low temperatures. Regular computer disks do not operate well in the cold, but newer flash disks work better.

"The number and depth of earthquakes in an area are important," says Anandakrishnan. "They provide a lot of information about what is going on beneath the earth, the types of faults and how they are moving."

In an area where a sheet of ice covers the ground, information about tectonic activity could provide information not available in any other way.
http://www.eurekalert.org/pub_releases/2002-05/ps-nsa052802.php

Satellites Show Alarming Retreat of Glaciers

By SPACE.com Staff
posted: 11:37 am ET
29 May 2002

Satellite imagery being presented today shows that the great majority of the world's glaciers are melting at rates equal to or greater than long-established trends, including some that are receding at alarming and accelerating paces.

If the climate warms at an accelerated rate over the next century, as some scientists predict, the glaciers would be adversely affected, scientists said.

Though most glaciers are receding, the joint study by NASA and the United States Geological Survey (USGS) found that a small minority of them are increasing their bulk. Early results of the project are being discussed today by Jeff Kargel, a USGS scientist, at the American Geophysical Union Spring Meeting in Washington, D.C.

The project, which involves scientists from 23 countries, uses satellites to map and examine glaciers throughout the world during the middle to latter part of the melt season when permanent ice is exposed. Current images are compared with older topographical maps and other records.

"Glaciers in most areas of the world are known to be receding," said Kargel, who heads up the project. "But glaciers in the Himalaya are wasting at alarming and accelerating rates, as indicated by comparisons of satellite and historic data, and as shown by the widespread, rapid growth of lakes on the glacier surfaces."

When ice melts and pools, the melt rate can increase dramatically. While ice reflects the Sun's rays, lake water absorbs and transmits heat more efficiently to the underlying ice, kicking off a feedback that creates further melting.

According to a 2001 report by the Intergovernmental Panel on Climate Change, scientists estimate that surface temperatures could rise by 1.4°C to 5.8°C by the end of the century. The researchers have found a strong correlation between increasing temperatures and glacier retreat.

Glacier changes in the next 100 years could significantly affect agriculture, water supplies, hydroelectric power, transportation, mining, coastlines, and ecological habitats, the research team predicts. Melting ice may cause both serious problems and, for the short term in some regions, helpful increases in water availability, but all these impacts will change with time, Kargel said.

For example, the Gangotri glacier between Kashmir and Nepal is retreating at an accelerated rate that cannot be accounted for by lingering effects from warming after the little ice age more than 200 years ago. The Gangotri glacier-and many others-feed the Ganges River Basin, upon which hundreds of millions of people, including those in New Delhi and Calcutta, depend for fresh water.

Kargel finds that over one percent of water in the Ganges and Indus Basins (South Asia) is currently due to runoff from wasting of permanent ice from glaciers. This contribution is expected to increase as melting rates accelerate, though ultimately the added runoff is predicted to disappear as glaciers decline many decades from now.

Such changes are important since water use in these basins is already approaching capacity as populations continue to grow, the researchers say. In drier parts of Asia, like in arid Western China, wasting glaciers currently account for over ten percent of fresh water supplies.

But the research finds positive aspects to glacier changes as well.

"It's not all doom and gloom," Kargel said. "Glaciers are wastelands, but as they recede the land underneath may become available for use."

The project primarily draws data from the ASTER (Advanced Spaceborne Thermal Emission and reflection Radiometer) instrument aboard the NASA's Earth Observing System (EOS) Terra spacecraft, launched in December 1999.
http://www.space.com/scienceastronomy/planetearth/glacier_retreat_020529.html

Antarctica becomes too hot for the penguins
Decline of 'dinner jacket' species is a warning to the world
Geoffrey Lean
03 February 2002
Penguins are starting to desert parts of Antarctica because the icy wastes are getting too hot.

The numbers of adelie penguins on the Antarctic peninsula – the most northerly part of the frozen continent – are falling as global warming takes hold. And experts predict that, as the climate change continues, they may abandon much of the 900-mile-long promontory altogether.

The archetypal "tuxedoed" species like the cold even more than other penguins. And the peninsula has been warming up faster than almost anywhere else on earth, with temperatures increasing at least five times faster than the world average. Scientists believe this is disrupting their food supplies.

Global warming is also causing them grief in another of their strongholds, the Ross Sea. Two giant icebergs have broken off the Antarctic ice sheet and are blocking the way from their breeding colonies to their feeding areas. As a result they have to walk 30 miles further to get food – no small matter when they can manage only one mile per hour. And, on the other side of the continent, thousands of emperor penguin chicks drowned near Britain's Halley base after the ice broke up early, before they had learned to swim.

Like miners' canaries, the dinner-jacketed penguins of Antarctica are providing an early warning of danger to come. For global warming is heating up the frozen continent faster than the rest of the world, and the penguins are among the first to feel the effects.

Flightless, and so unable to escape like other birds, they are affected by what happens both on land and sea. And, because they are easy to spot and count, they provide an early indication of what may be happening to other species.

They are feeling the heat most strongly on the Antarctic peninsula, which juts out from the polar land mass towards South America. Studies of air temperatures around the world over the past half-century suggest that this is one of the three areas on the planet – along with north-western North America and part of Siberia – warming up fastest. The British Antarctic Survey says flowering plants have spread rapidly in the area, glaciers are retreating, and seven huge ice sheets have melted away.

As the peninsula has warmed up, the numbers of adelie penguins have been dropping. Scientists suspect that the rising temperatures affect the small fish and other marine animals on which they feed, though they are not yet sure how.

Professor Steven Emslie, of the University of North Carolina, believes that if the warming goes on the penguins "would continue to decline in the peninsula, and may completely abandon much of it". Studies of fossilised remains that he has carried out near Britain's Rothera base show that the numbers of the penguins have sharply declined during warmer periods in prehistory.

On at least one occasion, the decline in the peninsula was marked by a rapid increase in the penguins in the Ross Sea more than 2,000 miles away. But in recent months global warming has been causing them trouble there too. Researchers for the US National Science Foundation said that one colony of adelies at Cape Royds will "fail totally" this year. And scientists at the Scripps Institute of Oceanography add that a colony of emperor penguins at Cape Crozier has also failed to raise any chicks.

Global warming also threatens the food supplies of emperor penguins. When there is less ice in the sea, populations of krill – a staple in their diet – fall.

Despite all this, penguins are not in danger of extinction; there are millions of them still in Antarctica and one species – the chinstrap penguin – seems to be thriving in the warmer weather. But they still provide a warning. In the words of the International Union for the Conservation of Nature, the world's leading conservation body: "Things happening to penguins are a foretaste of things to come."
http://news.independent.co.uk/world/environment/story.jsp?story=117890

posted 07-19-2002 02:17 AM               

Glacier Melting in Alaska Increasing

ASSOCIATED PRESS

WASHINGTON- Alaska's major glaciers are eroding so rapidly that researchers estimate they are losing 24 cubic miles of ice each year, adding to the steady rise in global sea level.

In a study appearing Friday in the journal Science, University of Alaska researchers said a survey of 67 major glaciers using an airborne laser system found that the rate of melting has hastened over the past five years.

"From the mid-1950s to the mid-1990s, the glaciers lost about 52 cubic kilometers (13 cubic miles) a year," said Anthony A. Arendt, first author of the study. "In the last five years, that rate has almost doubled."

Over almost a half century, he said, the glaciers have lost some 500 cubic miles of ice. The new measurements show that the glaciers of Alaska are contributing about half of the water worldwide flowing into the oceans from shrinking mountain glaciers, said Arendt.

Studies have suggested that the global sea level has risen about 7.8 inches over the past 100 years, and some experts say the rate is increasing. Arendt said that would be consistent with what he and his co-authors found in their study.

"The next question is what has been causing this glacier thinning. Is it because there is less snowfall in the winter or are the summers warmer?" said Arendt. "Glacier changes are linked to the climate, so this indicates that something has changed about the Alaskan climate."

Alaska's glaciers grow if they receive more snow in the winter than what melts in the summer. Because the glaciers are shrinking, then one end of this ice equation has changed. Arendt said that more study is needed to find out the causes.

Mark F. Meier, a glacier expert at the University of Colorado, Boulder, said the Alaskan study is an important advance in the efforts of science to understand the global climate. "For the first time we have some hard data from these glaciers which we have suspected, but didn't know for sure, are major contributors to the sea level change caused by glacier melt," Meier said.

The contribution from Alaska's glaciers to the worldwide sea level rise "is even more that what we had expected," he said.

Although Alaska contains 13 percent of the world's glacier-bound ice, the melt from its glaciers is greater than all the other glacier fields put together, excluding the ice fields in Greenland and Antarctica.

"Greenland is actually contributing less runoff than are these Alaskan glaciers," Meier said. "Greenland is much bigger, but it is much colder."

Experts have attributed sea level rise to two primary effects: runoff from the melting of ancient ice fields, such as the Alaskan glaciers, and an ocean expansion due to warming.

Some have attributed the warming of the ocean to a general global trend caused by human action.

posted 07-21-2002 02:07 AM               

Research Shows Alaskan Ice Mass Vanishing at Twice Rate Previously Estimated

By Eric Pianin
Washington Post Staff Writer

Friday, July 19, 2002; Page A14 Alaska's glaciers are melting at more than twice the rate previously thought because of warming temperatures, dramatically altering the majestic contours of the state and driving up sea levels, according to a new study.

Scientists using highly precise airborne laser measurements of 67 Alaskan glaciers from the mid-1950s to the mid-1990s discovered that the glaciers are melting an average of six feet a year -- and in some cases a few hundred feet -- and that the rate has accelerated in the past seven or eight years.

As one measure of the severity of the problem, the researchers calculated that the glaciers are generating nearly twice the annual meltage of the Greenland Ice Sheet, which is the largest ice mass in the Northern Hemisphere and second only to the Antarctic. That would mean the Alaskan melt is adding about two-tenths of a millimeter a year to sea levels -- a seemingly small rise that nevertheless could eventually have long-term implications for flooding on Pacific islands and along coastal areas, the researchers concluded.

The study by a team of researchers from the University of Alaska in Fairbanks, published in today's issue of the journal Science, offers a vivid and troubling picture of the potential adverse impact of climate change on the United States and the rest of the world.

"The change we are seeing is more rapid than any climate change that has happened in the last 10 to 20 centuries," said Keith A. Echelmeyer, one of the five researchers who prepared the study.

Scientists can't say whether the extraordinary melting is the result of man-induced global warming, the slow natural advance and rapid retreat of the glaciers, or dramatic but natural variations in weather patterns. But the phenomenon is an example of the kind of effects that can occur because of alterations in the Earth's climate.

"We're getting to the point that this melting is affecting human society," said Janine Bloomfield, a climate expert with Environmental Defense, an advocacy group. "Until now it was just warning signs and signals that the Earth was warming."

Indeed, the study has provided fresh evidence for Alaskan officials, researchers and environmentalists who say their state exemplifies the ills of global warming. Over the past 30 years alone, the annual mean temperature in Alaska has risen 5.4 degrees Fahrenheit -- four times the average global increase, according to the University of Alaska's Center for Global Change and Arctic System Research, an academic research center.

Some scientists theorize that the effects of climate change are most extreme in the northern part of the Northern Hemisphere because of a quirk in the way gases and the Earth's radiation get trapped in the atmosphere.

As the state's pervasive permafrost begins to thaw, the consequences are dramatic and alarming: sagging roads, crumbling villages, sinking pipelines, the proliferation of insects that are destroying spruce forests and the possible disruption of marine wildlife. Some Alaskans talk about "drunken trees" that list and show their roots because of the rapid decline of the permafrost.

"I see it as a trend that has to be taken seriously," said Gunter Weller of the Center for Global Change. "If these kinds of occurrences continue . . . it will have consequences around the world."

However, Sallie L. Baliunas of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., contends that the Alaskan melting is due to a dramatic but temporary shift in Pacific Ocean warm water and wind patterns that began in 1976. "It doesn't have the fingerprints of enhanced greenhouse gas concentrations," she said.

Sen. Ted Stevens (R-Alaska), who chaired public hearings in Fairbanks last year on global climate change, said, "Regardless of cause, many changes predicted worldwide appear to be happening first and with greater severity in arctic regions, including Alaska."

Past efforts to measure the decline of the Alaskan glaciers have been imprecise because they were largely based on observations and model simulations of glacier mass. Glaciers that were monitored routinely were often chosen more for their ease of access and manageable size than for how well they represented a given region or how large a contribution they might make to changing sea level.

The University of Alaska research team -- including Anthony A. Arendt, William D. Harrison, Craig S. Lingle, Virginia B. Valentine and Echelmeyer -- used laser devices aboard airplanes to measure the volume and area changes of the 67 glaciers, representing about 20 percent of the glacial area in Alaska and neighboring Canada.

The profiles developed were compared with contours on U.S. Geological Survey and Canadian topographic maps made from aerial photographs taken in the 1950s to early 1970s.

The study found that, during the past five to seven years, glacier thinning averaged about six feet a year, or twice as fast as that measured on the same glaciers from the mid-1950s to the mid-1990s.

(Because the glaciers are land-based, their meltage displaces water and pushes up the level of the ocean.) The annual meltage totaled 52 cubic kilometers and contributed about 9 percent of the observable rise in the sea level over the past half-century.

"Glaciers in Alaska are thinning quite rapidly . . . and it is due to climate change," Echelmeyer said. "What we don't know is if it's due to increased temperature or less snowfall, but it's definitely due to climate change."

http://www.washingtonpost.com/wp-dyn/articles/A25660-2002Jul18.html