Boston and New York are "directly in the path" of sea level rise

By 2100 visitors to Boston could be parking their boats, not their cars, in Harvard Yard.

Scientists believe that the influx of fresh water from the disintegrating ice sheets will disrupt a circulation pattern in the Atlantic Ocean, causing seas to expand.

The new projections call for an extra 4-12 inches (10.2-30.5 cm) on top of the rise of 8 inches (20.3 cm) previously estimated in the journal Nature Geoscience in March.

That previous study found that, if global warming continues, sea levels around New York City would rise by twice as much as in other parts of the United States within this century.

In the new study, researchers considered three scenarios: that Greenland's present melt rate of 7% would continue, or a drop to either 1-3% a year—viewed by many as more likely, as the rate is actually expected to slow in coming decades.

"We hope the high end wouldn't happen," said study lead author Aixue Hu of the National Center for Atmospheric Research in Boulder, Colorado.

But "we should be aware that there's a potential the melt of the Greenland ice sheet could be faster than we expected."

Vulnerable

Of the three scenarios, the two lower melt rates are more realistic, according to computer models of future ice sheet melting, Hu said.

A 3% melt rate would mean an extra 12 inches (30.5 cm) on top of the predicted global sea level rise of 21 inches (54 cm), and a 1% rate would mean an extra 8 inches (20.3 cm) for the region.

But if the current 7% rate were to persist, up to 20 inches (50 cm) of extra water would inundate cities such as New York and Halifax, Nova Scotia.

Still, Waleed Abdalati, a glaciologist at the University of Colorado, Boulder, said that the 7% scenario is really a worst case, particularly because "melt rate" is sometimes a misnomer, he said.

When glaciers break off into the ocean, they don't immediately melt, so scientists can't really say that all of Greenland's ice loss is due to melting, he explained.

But the finding is still important, he added, because "a few inches [of sea-level rise], depending on the time frame on which this occurs, makes a significant amount of difference," especially when it impacts heavily populated coastal areas.

What's more, previous studies had not taken into account how Greenland's melt might interact with an oceanic "conveyor belt" in the Atlantic Ocean, which transports water north from the tropics.

Normally in the belt tropical water gets cooler and becomes a deep layer of dense, cold water in the North Atlantic.

But the freshwater flow from Greenland slows down this conveyor belt and prevents the deep, dense water from accumulating. This would make deep water warmer and less dense, causing surface waters to expand throughout the North Atlantic.

It's for this reason that the northeast coast of North America is particularly vulnerable to rising seas, said Hu, whose research will appear May 29, 2009, in the journal Geophysical Research Letters.

Uncertainties

Such predictions, and the study of ice sheets in general, is often plagued with uncertainties.

For instance, scientists still don't understand ice sheet dynamics, such as how fast an unstable ice sheet will melt.

And data from the Intergovernmental Panel on Climate Change (IPCC)—which many researchers depend on as the gold standard in climate change predictions—can become easily outdated.

The 2007 IPCC assessment, for example, projected a sea-level rise of up to 23 inches (59 cm) this century. But the rapid decline of the world's ice sheets has led many researchers to believe the rise will be even greater.

"The more we know," said the University of Colorado's Abdalati, "the more we're finding things are more severe than we thought."

Link: http://news.nationalgeographic.com/news/2009/05/090528-greenland-melt.html

Arctic sea ice thinnest ever going into spring

AFP/LAVAL UNIVERSITY/File – This image shows Markham Fiord, in August 2008, after the Markham Ice Shelf broke away. "In the …

• Play Video Video:Polar ice cap health KVUE-TV Austin

WASHINGTON – The Arctic is treading on thinner ice than ever before. Researchers say that as spring begins, more than 90% of the sea ice in the Arctic is only 1 or 2 years old. That makes it thinner and more vulnerable than at anytime in the past three decades, according to researchers with NASA and the National Snow and Ice Data Center in Colorado.

"We're not set up well for summertime," ice data center scientist Walt Meier said Monday. "We're in a very precarious situation."

Young sea ice in the Arctic often melts in the spring and summer. If it survives for two years, then it becomes the type of thick sea ice that is key. But the past two years were warm, and there's more young, thin ice at the top of the world.

In normal winters, thick sea ice — often about 10 feet thick or more — extends from the northern boundaries of Greenland and Canada almost to Russia. This year, the thick ice cap barely penetrates the bull's-eye of the Arctic Circle.

The amount of thick sea ice hit a record wintertime low of just 378,000 square miles this year, down 43% from last year, Meier said. The amount of older sea ice that was lost is larger than the state of Texas.

"That thick ice really traps ocean heat; it keeps the planet in its current state of balance," said Waleed Abdalati, director of the Center for the Study of Earth from Space at the University of Colorado and NASA's former chief ice scientist. "When we start to diminish that, the state of balance is likely to change, tip one way or another."

Sea ice is important because it reflects sunlight away from Earth. The more it melts, the more heat is absorbed by the ocean, heating up the planet even more, said NASA polar regions program manager Tom Wagner. That warming also can change weather patterns worldwide and it alters the ecosystems for animals such as polar bears.

The Arctic essentially acts as a refrigerator for the rest of the globe. And the amount of sea covered by ice — thick or thin — has been shrinking at a rate of about 3% a decade in the Arctic.

This year, the maximum ice cover of 5.85 million square miles — reached on Feb. 28 — was higher than four of the previous five years. But it was still the fifth lowest since record-keeping began in 1979.

Usually, younger, thin ice accounts for about 70% of the ice cover. This year it reached 90%, Meier said.

And the problems of global warming caused melt is being seen at the other pole, too.

The U.S. Geological Survey last week released a detailed map of the Antarctic coastline and found dwindling and even disappearing ice shelves.

The map itself was finished in the middle of last year, but the previous Interior Department didn't want to release it and other Antarctic maps, said map co-author Richard Williams Jr., a glaciologist for the USGS. The report with the map bears the 2008 date and the previous interior secretary's name on it.

The map shows found for the first time that an entire ice shelf — the Wordie ice shelf on the western end of the Antarctic peninsula — has essentially disappeared. In 1966, it was 772 square miles. In addition, about 4,500 square miles of the Larsen ice shelf is gone.

"The map portrays one of the most rapidly changing areas on Earth, and the changes in the map are widely regarded as among the most profound, unambiguous examples of the effects of global warming on Earth," the USGS report concludes.

Link to article: http://news.yahoo.com/s/ap/20090406/ap_on_sc/arctic_ice

Sound the alarm on climate change

by Waleed Abdalati

Article Last Updated: 12/18/2008

Environmental scientists who have been watching Earth's climate change dramatically in recent decades recognize an immediate need for comprehensive, coordinated action to address the threats of climate change.

From ground and from space, we see an Arctic in the midst of rapid change: The blanket of sea ice that once covered much of the Arctic Ocean in summer is disappearing. Once-frozen soils are thawing, and buildings, pipelines and forests lean on sinking foundations. Glaciers are disintegrating and ice sheets are shedding massive amounts of ice, feeding already-rising seas.

As predicted for decades, human- caused warming is sweeping across the Earth. This will have impact on water resources, public health, coastal infrastructure, ecosystems and agriculture. No place on the planet will be left untouched.

Leaders in both major parties have given voice to concerns about climate change. Now is the time to act, and swiftly. Climate change is critical to the U.S. economy, national security, international standing, and environmental and cultural heritage. Consider the findings of thousands of scientists around the globe:

• Dwindling sea ice. Since the advent of satellite monitoring in the 1970s, summer Arctic sea ice extent has declined by 39 percent, further amplifying warming and having significant biological, ecological and societal impacts.

• Thawing ground. Across the Arctic, permafrost has warmed up to 13 degrees in the last century — with about half of that increase occurring in the last 25 years. Degrading permafrost releases ancient stored carbon, creating a warming feedback not yet included in most climate models.

• Ice loss in Greenland. Warming has caused a 30 percent increase in melt area of the Greenland ice sheet since 1979, and ice now flows off the sheet much faster than a decade ago.

• Ice loss in Antarctica. Oceanic and atmospheric patterns have protected most of Antarctica from warming. However, the Antarctic Peninsula, which juts into the southern Atlantic, has warmed by about 4 1/2 degrees in the last 50 years. Ice shelves the size of small states have begun disintegrating.

• Rising seas. Oceans are rising because of melting glaciers and ice sheets and because water expands as it warms. Seas have risen twice as quickly in the last 15 years than in the previous 50, and at the current rate of warming, will rise another foot by 2100. However, if warming continues to accelerate and polar ice sheets begin to shrink more rapidly, a rise of 3 feet or much more is possible. That would affect 145 million people around the world, at a cost of nearly $1 trillion, according to the United Nations.

Areas of uncertainty remain, from the roles that air pollution and clouds will play in a warming world to the effect of warmer oceans on hurricanes. But we have enough data today to compel global mitigation, to reduce emissions and lessen the impact of climate change in the future.

Climate change is not an intractable issue. Other harmful global environmental trends have been successfully addressed, most notably the destruction of the ozone layer. We believe such nimble responses are again possible and necessary, to reduce greenhouse gas emissions and prepare communities for change. As before, with great leadership, these actions will create new opportunities for our country to prosper.

We ask President-elect Barack Obama to lead us and the international community — now.

Waleed Abdalati is head of NASA's Cryospheric Sciences Branch at the Goddard Space Flight Center (GSFC) in Greenbelt, Md. Other signers were Walter Meier, Steven Nerem, Mark Serreze, Konrad Steffen, Julienne Stroeve, John Wahr, and Tingjun Zhang, climate scientists and professors at the University of Colorado Boulder. (The opinions expressed do not necessarily reflect the views of CU.)

WASHINGTON — In northern Greenland, a part of the Arctic that had seemed immune from global warming, new satellite images show a growing giant crack and an 11-square-mile chunk of ice hemorrhaging off a major glacier, scientists said Thursday.

And that's led the university professor who spotted the wounds in the massive Petermann glacier to predict disintegration of a major portion of the Northern Hemisphere's largest floating glacier within the year.

If it does worsen and other northern Greenland glaciers melt faster, then it could speed up sea level rise, already increasing because of melt in southern Greenland.

The crack is 7 miles long and about half a mile wide. It is about half the width of the 500 square mile floating part of the glacier. Other smaller fractures can be seen in images of the ice tongue, a long narrow sliver of the glacier.

"The pictures speak for themselves," said Jason Box, a glacier expert at the Byrd Polar Research Center at Ohio State University who spotted the changes while studying new satellite images. "This crack is moving, and moving closer and closer to the front. It's just a matter of time till a much larger piece is going to break off.... It is imminent."

The chunk that came off the glacier between July 10 and July 24 is about half the size of Manhattan and doesn't worry Box as much as the cracks. The Petermann glacier had a larger breakaway ice chunk in 2000. But the overall picture worries some scientists.

"As we see this phenomenon occurring further and further north — and Petermann is as far north as you can get — it certainly adds to the concern," said Waleed Abdalati, director of the Center for the Study of Earth from Space at the University of Colorado.

The question that now faces scientists is: Are the fractures part of normal glacier stress or are they the beginning of the effects of global warming?

"It certainly is a major event," said NASA ice scientist Jay Zwally in a telephone interview from a conference on glaciers in Ireland. "It's a signal but we don't know what it means."

It is too early to say it is clearly global warming, Zwally said. Scientists don't like to attribute single events to global warming, but often say such events fit a pattern.

University of Colorado professor Konrad Steffen, who returned from Greenland Wednesday and has studied the Petermann glacier in the past, said that what Box saw is not too different from what he saw in the 1990s: "The crack is not alarming... I would say it is normal."

However, scientists note that it fits with the trend of melting glacial ice they first saw in the southern part of the massive island and seems to be marching north with time. Big cracks and breakaway pieces are foreboding signs of what's ahead.

Further south in Greenland, Box's satellite images show that the Jakobshavn glacier, the fastest retreating glacier in the world, set new records for how far it has moved inland.

That concerns Colorado's Abdalati: "It could go back for miles and miles and there's no real mechanism to stop it."

Ohio State University images and data: http://bprc.osu.edu/MODIS/

The scientists also said that the margin of the massive Jakobshavn glacier has retreated inland further than at any time in the past 150 years of observation.

They believe, moreover, that it has not retreated so far inland "in at least the last 4,000 to 6,000 years."

Jakobshavn's northern branch has broken up in the last several weeks and the glacier has lost at least 10 square kilometers (three square miles) since the end of the last melt season, the researchers said.

About one-tenth of Greenland's icebergs come from Jakobshavn, making it the island's most productive glacier.

The glacier lost 94 square kilometers (36 square miles) of ice field betwen 2001 and 2005, a phenomenon that drew international attention to the impact of global warming on glaciers, the scientists said.

Meanwhile, the roof of an ice tunnel in Argentina's gigantic Perito Morena glacier, 60 meters high and weighing thousands of tonnes, suddenly collapsed July 8, a phenomenon unheard of in the dead of the southern hemisphere winter.

Scientists blamed global warming for the collapse.

Journal of Geophysical Research, Vol. 109, F04007, doi:10.1029/2003JF000045, 2004

W. Abdalati (NASA Goddard Space Flight Center, Greenbelt, Maryland, USA); W. Krabill (Wallops Flight Facility, NASA Goddard Space Flight Center, Wallops Island, Virginia, USA); E. Frederick, S. Manizade, C. Martin, J. Sonntag, R. Swift, R. Thomas, and J. Yungel (EG&G, Wallops Flight Facility, NASA Goddard Space Flight Center, Wallops Island, Virginia, USA); R. Koerner (Geological Survey of Canada, Ottawa, Ontario, Canada)

Precise repeat airborne laser surveys were conducted over the major ice caps in the Canadian Arctic Archipelago in the spring of 1995 and 2000 in order to measure elevation changes in the region. Our measurements reveal thinning at lower elevations (below 1600 m) on most of the ice caps and glaciers but either very little change or thickening at higher elevations in the ice cap accumulation zones. Recent increases in precipitation in the area can account for the slight thickening where it was observed but not for the thinning at lower elevations. For the northern ice caps on the Queen Elizabeth Islands, thinning was generally <0.5>−1, which is consistent with what would be expected from the warm temperature anomalies in the region for the 5 year period between surveys, and appears to be a continuation of a trend that began in the mid-1980s. Farther south, however, on the Barnes and Penny ice caps on Baffin Island, this thinning was much more pronounced at over 1 m yr⁻¹ in the lower elevations. Here temperature anomalies were very small, and the thinning at low elevations far exceeds any associated enhanced ablation. The observations on Barnes, and perhaps Penny, are consistent with the idea that the observed thinning is part of a much longer term deglaciation, as has been previously suggested for Barnes ice cap. On the basis of the regional relationships between elevation and elevation change in our data, the 1995–2000 mass balance for the archipelago is estimated to be −25 km³ yr⁻¹ of ice, which corresponds to a sea level increase of 0.064 mm yr⁻¹. This places it among the more significant sources of eustatic sea level rise, though not as substantial as the Greenland ice sheet, Alaskan glaciers, or the Patagonian ice fields.

Received 17 April 2003; accepted 8 September 2004; published 20 November 2004.

Keywords: ice caps, Arctic, mass balance

Index Terms: 1640 Global Change: Remote sensing; 1699 Global Change: General or miscellaneous; 1827 Hydrology: Glaciology (1863); 1863 Hydrology: Snow and ice (1827).

Read Full Article (file size: 1519739 bytes) Cited by

Citation: Abdalati, W., W. Krabill, E. Frederick, S. Manizade, C. Martin, J. Sonntag, R. Swift, R. Thomas, J. Yungel, and R. Koerner (2004), Elevation changes of ice caps in the Canadian Arctic Archipelago, J. Geophys. Res., 109, F04007, doi:10.1029/2003JF000045.

Copyright 2004 by the American Geophysical Union.

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Combining ICESat and Aircraft Laser Altimetry Observations to Examine Recent Changes in Canadian Ice Caps

Abstract

Effects of Climate Change on Baffin Island's Glaciers

"In the Arctic, where the regional-scale positive albedo feedbacks and
interactions between ocean, atmosphere, and sea ice are expected to
amplify the effects of climate change" (Cubasch et al., 2001).

Climate Change in the Canadian Arctic:

Holocene climate change in the Eastern Canadian Arctic has been influences by 3 factors: (1) the impact on atmospheric circulation by the waning Laurentide Ice Sheet (2) the steady decrease in summer solar insolation as regular changes in the Earth’s orbit diminished Northern Hemisphere seasonality and (3) changes in the balance between relatively warm, salty Atlantic water and the outflow of cold, low-salinity surface water from the Arctic Ocean. (Miller et al. 2005) Baffin Island’s glacial features have been affected by the warming trend experienced in the Holocene. At the peak of the last glacial maximum, warm based outlet glaciers occupied most fiords and sounds, but significant portions of Baffin Island were covered by cold based ice. By the beginning of the Holocene, the Eastern Canadian Arctic had warmed enough that most glaciers were warm based and deglaciation can deciphered from moraines, ice-con-tact deposits and from sediment cores taken. (Miller et al. 2005).

Glacier Change and Climate Change in Nunavut:

The advance and retreat of glaciers have long been understood to be tied to climate change (Ahlmann, 1953 in Bell and Jacobs, 1997).

Throughout the islands in Nunavut, evidences suggest recent neoglacial events that ended in the latter part of the 19th century (Bell and Jacobs, 1997). Glaciological data from the 20th century indicate a renewed glacial retreat from recent terminal moraines (Bell and Jacobs, 1997). The mass balance of glaciers in the area has shown be most influenced by summer near-surface air temperature, followed by winter precipitation (Johannesson et al., 1995 in Bell and Jacobs, 1997). Glacier studies completed in Nunavut, for example, of Boas in 1975, the Grinnell in 1956 and the White (Axel Heiberg) in 1995 showed that one warm summer can melt the net accumulation from a number of successive positive mass balance years (Bell and Jacobs, 1997). This is especially of interest under the current global warming trend.

In 1992, using glaciers from a wide range of climatic regimes, Oerlemans and Fortuin examined the sensitivities of glaciers and small ice caps to global warming (Bell and Jacobs, 1997). They found that under the condition of a uniform 1 K warming, the glacier mass balance will be lowered by 0.4 m/a and this corresponds to an increase of 0.58 mm/a in sea level (Bell and Jacobs, 1997).

Due to the logistic problems associated with completing research in remote sites, continuous field glacier monitoring in the High Arctic is limited to only a few glaciers, mostly confined to the Queen Elizabeth Islands (Bell and Jacobs, 1997). Bell and Jacobs (1997) suggests that Canada can adopt the data collection method used by Iceland, there, the Icelandic glacier observation program train laypeople living near glaciers how to measure and observe glacial patterns (Bell and Jacobs, 1997). In addition, with the recent advancement of satellite imagery, data is becoming more readily available.

From the 1960s to the 1990s, Baffin Island experienced a general cooling trend rather than a global warming trend like elsewhere in Nunavut (Bell and Jacobs, 1997). If this pattern continues, the resulting effects it is still uncertain.

Figure 1 Southernly ice caps in the Canadian Arctic Archipelago show higher thinning
rates than more northernly ice caps (Abdalati et al., 2004).

Figure 2: Annual mass balance (from 1960-1983) plotted against departure of Clyde summer temperature from the mean of
1960-1993. JJA stands for June, July, August (Bell and Jacobs, 1997).

LINKS:
C-GIP HOME PAGE
Baffin Island Introduction

Glaciated Peninsulas Include:

Brodeur Peninsula Cumberland Peninsula Hall Peninsula Meta Incognita Peninsula
Ice Caps on Baffin Island Include:
Barnes Ice Cap Grinnell Ice Cap Penny Ice Cap Terra Nivea Ice Cap
Glacial features in Cumberland Peninsula Include:
Boas Glacier Caribou Glacier Coronation Glacier Fork Beard Glacier Highway Glacier
Penny Ice Cap Tumbling Glacier
Glacial features in Hall Peninsula Include:
Grinnell Ice Cap
Glacial features in Meta Incognita Peninsula Include:
Terra Nivea Ice Cap
Additional Links:
Decade Glacier Effects of Climate Change on Baffin References

Link: http://cgip.wetpaint.com/page/Effects+of+Climate+Change+on+Baffin+Island's+Glaciers?t=anon

Waleed Abdalati: “With an ice-free Arctic--more heat is absorbed by the planet. Throughout recorded history, we’ve counted on this ice being there.”

These “awakening” or thawing ice sheets will affect the world, from raising sea levels and threatening the existence of polar bears, to expanding maritime commerce and impacting national security, Abdalati noted.

One of the world's pre-eminent experts in the study of climate change, Abdalati provided evidence that the polar ice sheets are shrinking, drawing on data yielded by some 14 different scientific models used for predicting climate, to striking images of Greenland's and Antarctica's ice cover taken by NASA satellites.

The presentation was the latest installment in UD's William S. Carlson International Polar Year Events--a series of public programs named after UD's president from 1946-50 who conducted research in the Arctic. The lecture also was Webcast and simulcast to UD's island in the virtual world of Second Life.

Abdalati said he “fell in love with NASA” as a youngster, after watching the lunar landings. Today, he leads a group of scientists who monitor the planet's changing ice cover using satellites and other airborne instruments. He also is a veteran of nine field expeditions to the Greenland Ice Sheet.

“It's nature in its most austere form,” Abdalati said, showing a slide of a helicopter hovering along the edge of the Antarctic ice shelf towering taller than a football field above the waterline. “Does it matter that a place like this is changing?” he asked.

While Abdalati says the polar ice sheets “won't go tomorrow,” how much sea level rises in the future and how well we are prepared for it has huge social, political and economic implications for the world.

The impact of a one-meter (3.2 foot) rise in sea level in the world's oceans would amount to the inundation of 2.2 million square miles of coastline around the globe, the equivalent of one-quarter of the continental United States. It would affect 45 million people and cost a trillion dollars, Abdalati said.

Tools such as ice-penetrating radar and NASA's ICESat satellite have revealed that the Greenland Ice Sheet has a “weakened underbelly,” eroded by meltwater from thawing ice on the surface.

Since 1979, sea ice has been shrinking by about 8 percent per decade, Abdalati said. Every summer, sea ice thaws until it reaches a summer minimum. Then nature “presses a re-set button,” and the sea ice grows back in winter, he noted. However, the thick, old ice no longer exists in many places, leaving much thinner ice, more vulnerable to melting.

In 2007, scientists were stunned by the 23 percent reduction in sea ice that occurred from 2005-07. In 2007, a 76-year-old farmer from Minnesota navigated the largely ice-free Northwest Passage in a sailboat, he noted.

An ice-free Arctic Ocean has both negative and positive implications, Abdalati noted, providing the means for moving goods from Asia to Europe more quickly, and reducing the need to use the Suez Canal, not to mention increasing access to the Arctic's tremendous economic resources.

As this frozen ground melts, it releases methane, a strong greenhouse gas. Melting permafrost already is costing Alaska some $35 million per year, where homes, highways and other infrastructure are affected by the sinking ground.

“Climatologically, we're in unfamiliar territory,” Abdalati noted. “The effectiveness of society's response depends on how big the changes are, how fast they come and how fast our ability will be to anticipate the changes.”

For information on UD's polar research and outreach activities, visit [www.udel.edu/research/polar].

Photos by Jon Cox and Debbie Jeffers

Link to article: http://www.udel.edu/PR/UDaily/2008/apr/giants041608.html

Thin layer vulnerable to summer melting, federal scientists say

by Seth Borenstein, Associated Press, March 19, 2008

WASHINGTON -- Critical Arctic sea ice this winter made a tenuous partial recovery from last summer's record melt, federal scientists said Tuesday.

But that's an illusion, like a Hollywood movie set, scientist Walter Meier of the National Snow and Ice Data Center said. The ice is very thin and vulnerable to heavy melting again this summer.

Overall, Arctic sea ice has shrunk precipitously in the past decade and scientists blame global warming caused by humans.

Last summer, Arctic ice shrank to an area that was 27 percent smaller than the previous record. This winter, it recovered to a maximum of 5.8 million square miles, up 4 percent and the most since 2003, NASA ice scientist Josefino Comiso said. It is still a bit below the long-term average level for this time of year.

"What's going on underneath the surface is really the key thing," Meier said after a news conference. What's happening is not enough freezing, he said.

Summer Arctic sea ice is important because it's intricately connected to weather conditions elsewhere on the globe. It affects wind patterns, temperatures farther south and even the Gulf Stream, acting as a sort of refrigerator for the globe, according to scientists.

"What happens there, matters here," said Waleed Abdalati, chief ice scientist at NASA's Goddard Space Flight Center in Greenbelt, Md. "Climate for the period of human record has depended on the ice being there."

Viewing the Arctic from space via NASA satellites might make you think the Arctic ice cover is on its way back.

But more than 70 percent of that sea ice is new, thin and salty, having formed only since September, Comiso said. The more important ice is perennial sea ice that lasts through the summer, and that ice has hit record low levels.

Compared to the 1980s, the Arctic has lost more than half of its perennial sea ice and three-quarters of its "tough as nails" sea ice that is six years or older, Meier said. The amount of lost old sea ice is twice the area of the state of Texas, he said.

On top of that, a change in Arctic atmospheric pressure this winter is pushing a large amount of the valuable older ice out of the Arctic to melt, Meier said.

That means next summer when temperatures warm, expect lots of melting, the scientists said.

"We're in for a world of hurt this summer," ice center senior scientist Mark Serreze told the Associated Press. Depending on the weather, there could be as much melting this year as last, maybe more, Serreze and Meier said.

At the South Pole, in Antarctica, sea ice seems stable, even slightly above normal, the scientists reported. However, ice levels in Antarctica always are quite different from the Arctic and aren't as connected to the world's weather.

Thin layer vulnerable to summer melting, federal scientists say

by Seth Borenstein, Associated Press, March 19, 2008

WASHINGTON -- Critical Arctic sea ice this winter made a tenuous partial recovery from last summer's record melt, federal scientists said Tuesday.

But that's an illusion, like a Hollywood movie set, scientist Walter Meier of the National Snow and Ice Data Center said. The ice is very thin and vulnerable to heavy melting again this summer.

Overall, Arctic sea ice has shrunk precipitously in the past decade and scientists blame global warming caused by humans.

Last summer, Arctic ice shrank to an area that was 27 percent smaller than the previous record. This winter, it recovered to a maximum of 5.8 million square miles, up 4 percent and the most since 2003, NASA ice scientist Josefino Comiso said. It is still a bit below the long-term average level for this time of year.

"What's going on underneath the surface is really the key thing," Meier said after a news conference. What's happening is not enough freezing, he said.

Summer Arctic sea ice is important because it's intricately connected to weather conditions elsewhere on the globe. It affects wind patterns, temperatures farther south and even the Gulf Stream, acting as a sort of refrigerator for the globe, according to scientists.

"What happens there, matters here," said Waleed Abdalati, chief ice scientist at NASA's Goddard Space Flight Center in Greenbelt, Md. "Climate for the period of human record has depended on the ice being there."

Viewing the Arctic from space via NASA satellites might make you think the Arctic ice cover is on its way back.

But more than 70 percent of that sea ice is new, thin and salty, having formed only since September, Comiso said. The more important ice is perennial sea ice that lasts through the summer, and that ice has hit record low levels.

Compared to the 1980s, the Arctic has lost more than half of its perennial sea ice and three-quarters of its "tough as nails" sea ice that is six years or older, Meier said. The amount of lost old sea ice is twice the area of the state of Texas, he said.

On top of that, a change in Arctic atmospheric pressure this winter is pushing a large amount of the valuable older ice out of the Arctic to melt, Meier said.

That means next summer when temperatures warm, expect lots of melting, the scientists said.

"We're in for a world of hurt this summer," ice center senior scientist Mark Serreze told the Associated Press. Depending on the weather, there could be as much melting this year as last, maybe more, Serreze and Meier said.

At the South Pole, in Antarctica, sea ice seems stable, even slightly above normal, the scientists reported. However, ice levels in Antarctica always are quite different from the Arctic and aren't as connected to the world's weather.

ON THE WEB

NASA images and graphics about sea ice:

Link to this article: http://www.delawareonline.com/apps/pbcs.dll/article?AID=/20080319/NEWS08/803190352