Scientists predict Arctic could be ice-free within decades

Physorg.com on March 25, 2011 By Nancy Atkinson, Universe Today – Original article here

Scientists predict arctic could be ice-Free within decades
Sea ice data through mid- March 2011. Credit: National Snow and Ice Data Center

Bad news for what is now the beginning of the “melt season” in the Arctic. Right now, the sea ice extent maximum appears to be tied for the lowest ever measured by satellites as the spring begins, according to scientists at the University of Colorado Boulder’s National Snow and Ice Data Center. And because of the trend of how the amount of Arctic sea ice has been spiraling downward in the last decade, some scientists are predicting the Arctic Ocean may be ice free in the summers within the next several decades.

“I’m not surprised by the new data because we’ve seen a downward trend in winter sea ice extent for some time now,” said Walt Meier, a research scienitist with the NSIDC.

The seven lowest maximum Arctic sea ice extents measured by satellites all have occurred in the last seven years, and the from the latest data, the NSIDC research team believes the lowest annual maximum ice extent of 5,650,000 square miles occurred on March 7 of this year.

The maximum ice extent was 463,000 square miles below the 1979-2000 average, an area slightly larger than the states of Texas and California combined. The 2011 measurements were tied with those from 2006 as the lowest maximum sea ice extents measured since record keeping began in 1979.

Virtually all climate scientists believe shrinking Arctic sea ice is tied to warming temperatures in the region caused by an increase in human-produced greenhouse gases being pumped into Earth’s atmosphere.

Meier said the Arctic sea ice functions like an air conditioner for the global climate system by naturally cooling air and water masses, playing a key role in ocean circulation and reflecting solar radiation back into space. In the Arctic summer months, sunlight is absorbed by the growing amounts of open water, raising surface temperatures and causing more ice to melt.

“I think one of the reasons the Arctic sea ice maximum extent is declining is that the autumn ice growth is delayed by warmer temperatures and the ice extent is not able to ‘catch up’ through the winter,” said Meier. “In addition, the clock runs out on the annual ice growth season as temperatures start to rise along with the sun during the spring months.”

Since satellite record keeping began in 1979, the maximum ice extent has occurred as early as Feb. 18 and as late as March 31, with an average date of March 6. Since the researchers determine the maximum extent using a five-day running average, there is small chance the data could change.

As of March 22, ice extent declined for five straight days. But February and March tend to be quite variable, so there is still a chance that the ice extent could expand again. Ice near the edge is thin and is highly sensitive to weather, scientists say, moving or melting quickly in response to changing winds and temperatures, and it often oscillates near the maximum extent for several days or weeks, as it has done this year.

In early April the NSIDC will issue a formal announcement on the 2011 maximum with a full analysis of the winter ice growth season, including graphics comparing 2011 to the long-term record.

U.S. Navy Scrambles for Piece of Arctic Pie (Pentland/Forbes)

William Pentland/Forbes Mar. 25 2011 – Original article here

The U.S. Navy is staging the aquatic-equivalent of a dog-and-pony show in the Arctic Ocean this month with a small fleet of nuclear-powered submarines.

The military exercises are designed to bolster U.S. claims on emerging – and likely lucrative – commercial opportunities in the region, which have attracted intense interest in recent years as global warming accelerates what appears to be the permanent loss of sea ice in the Arctic.

The National Snow and Ice Data Center reported in early March that 2011 has tied with 2006 for the record low sea-ice coverage in the Arctic Ocean (in the satellite record). By the mid-2030s, scientists have predicted that the Arctic will be ice-free for at least one month of every summer, which will expand to two-to-three ice-free months by around mid-century.

The U.S. Navy has deployed two nuclear-powered submarines off the coast of Alaska close to a temporary camp constructed on the ice roughly 150 miles north of Prudhoe Bay. The submarines are conducting military training exercises.

Credit: National Snow and Ice Data Center

On March 7, 2011, the winter ice covering the Arctic reached its maximum size for the year at 5.65 million square miles, which is more than 20% below – or, 463,000 square miles – below the average annual coverage from 1979 to 2000 (6.12 million square miles). The orange line shows the 1979 to 2000 median extent for that day. The black cross indicates the geographic North Pole.

The exercises train U.S. submarine crews to deal with craggy ice keels that extend 20 to 50 feet into the water, and varying salinity levels that complicate communications and navigation under the ice cap.

Submarine crews practice surfacing the 8,000-ton submarines, directly through thick ice or in nearby open waters, and learn to avoid hitting another ship. The ice exercise, which did not include any torpedo testing, cost an estimated $3.5 million, according to Larry Estrada, director of the Arctic Submarine Laboratory which manages the camps with the Applied Physics Laboratory of the University of Washington

Credit: National Snow and Ice Data CenterThe graph above shows daily Arctic sea ice extent as of March 22, 2011, along with daily ice extents for 2006, which had the previous lowest maximum extent, and 2007, the year with the lowest minimum extent in September. Light blue indicates 2011, green shows 2007, light green shows 2006, and dark gray shows the 1979 to 2000 average. The gray area around the average line shows the two standard deviation range of the data. Credit: National Snow and Ice Data Center

A delegation of defense contractors and military brass visited the camp last week, according to Reuters. The training was meant to ensure that the United States maintained access to the Arctic, home to the world’s largest undiscovered oil and gas reserves. Russia, the United States, Denmark, Greenland, Canada and Norway, which border the Arctic, and China are also scrambling to control the region and access to the commercial ventures there.

“It is a key potential transit line between the Atlantic and the Pacific,” U.S. Navy Captain Rhett Jaehn, told Reuters. “We want to be able to demonstrate that we have global reach. That we can operate in all oceans, and that we can operate proficiently in any environment.”

Jaehn is the commanding officer for the more than two dozen Navy officials, researchers, engineers and scientists working at the temporary ice camp. Ironically, finding a thick enough ice sheet to support the temporary camp was among the difficulties the Navy encountered this year.

Receding ice levels are likely to open new shipping routes in the Arctic, which could ultimately make the Bering Strait between Russia and Alaska a compelling alternative to shipping lanes in the Persian Gulf and Indian Ocean.

Ancient Fossils Show Arctic Now Near Climate Tipping Point

BOULDER, Colorado, June 29, 2010 (ENS) – Current levels of Earth’s atmospheric carbon dioxide may be high enough to bring about “irreversible” shifts in Arctic ecosystems, according to new research published today by scientists from the United States, Canada and The Netherlands.

The Arctic climate system is more sensitive to greenhouse warming than previously known said the researchers, who gathered evidence on what is now Ellesmere Island in Canada’s High Arctic from a time period 2.6 to 5.3 million years ago. This period, known as the Pliocene Epoch, occurred shortly before Earth was plunged into an ice age.

“Our findings indicate that CO2 levels of approximately 400 parts per million are sufficient to produce mean annual temperatures in the High Arctic of approximately zero degrees Celsius (32 degrees F),” said lead author Ashley Ballantyne of the University of Colorado at Boulder.

“As temperatures approach zero degrees Celsius, it becomes exceedingly difficult to maintain permanent sea and glacial ice in the Arctic. Thus current levels of CO2 in the atmosphere of approximately 390 parts per million may be approaching a tipping point for irreversible ice-free conditions in the Arctic,” Dr. Ballantyne warned.

From left: Ashley Ballantyne of CU-Boulder, Dara Finney of Environment Canada and Natalia Rybczynski of the Canadian Museum of Nature dig for fossils near Strathcona Fiord on Ellesmere Island. (Photo courtesy Environment Canada)

The research team points out that the overwhelming majority of climate scientists agree Earth is warming due to increased atmospheric concentrations of heat-trapping gases generated by human activities like fossil fuel burning and deforestation.

Arctic temperatures have risen by about 1.8 degrees F (1 degree C) in the past two decades in response to human-caused greenhouse warming, a trend expected to continue in the coming decades and centuries, said Ballantyne.

Greenhouse gases in the atmosphere have risen from about 280 parts per million during the pre-industrial era on Earth to about 390 parts per million today.

Environmental advocates are calling on governments negotiating the next climate treaty to limit greenhouse gas emissions to 350 parts per million, the level many scientists say will help to avert the worst consequences of climate change.

The research paper is being published in the July issue of the journal “Geology.” The study was funded by the U.S. National Science Foundation, the Natural Science and Engineering Research Council in Canada, the Netherlands Organization for Scientific Research and the European Research Council.

Co-authors included David Greenwood of Brandon University in Manitoba, Canada; Jaap Sinninghe Damste of the Royal Netherlands Institute for Sea Research; Adam Csank of the University of Arizona; Natalia Rybczynski of the Canadian Museum of Nature in Ottawa; and Jaelyn Eberle, curator of fossil vertebrates at the University of Colorado Museum of Natural History and an associate professor in the geological sciences department.

“Our findings are somewhat disconcerting regarding the temperatures and greenhouse gas levels during the Pliocene,” said Eberle. “We already are seeing evidence of both mammals and birds moving northward as the climate warms, and I can’t help but wonder if the Arctic is headed toward conditions similar to those that existed during the Pliocene.”

At the Ellesmere Island research site, called the Beaver Pond site, organic materials have been “mummified” in peat deposits, allowing the researchers to conduct detailed, high-quality analyses, said Eberle.

They found that in the Pliocene, Ellesmere Island had forests of larch, dwarf birch and northern white cedar trees, as well as mosses and herbs.

The island was inhabited by fish, frogs and mammals now extinct, including tiny deer, ancient relatives of the black bear, three-toed horses, small beavers, rabbits, badgers and shrews.

But the research value of the site is now threatened by a proposed coal mine. Eberle said there is high concern by scientists over a proposal to mine coal on Ellesmere Island near the Beaver Pond site by WestStar Resources Inc., a mineral exploration company headquartered in Vancouver, British Columbia.

The Beaver Pond site is close to Strathcona Fiord on Ellesmere Island in the Canadian Territory of Nunavut. In the 1980s, reconnaissance exploration conducted by Petro-Canada and others described coal seams up to 12 meters (39 feet) thick close to the surface along the steep north shore of the fiord.

“Paleontological sites like the Beaver Pond site are unique and extremely valuable resources that are of international importance,” said Eberle. “Our concern is that coal mining activities could damage such sites and they will be lost forever.”

For this study, the team used three independent methods of measuring the Pliocene temperatures on Ellesmere Island.

They measured oxygen isotopes found in the cellulose of fossil trees and mosses that reveal temperatures and precipitation levels tied to ancient water.

They analyzed the distribution of lipids in soil bacteria which correlate with temperature.

And they inventoried ancient Pliocene plant groups that overlap in range with contemporary vegetation.

“The results of the three independent temperature proxies are remarkably consistent,” said Eberle. “We essentially were able to ‘read’ the vegetation in order to estimate air temperatures in the Pliocene.”

The scientists found that while the mean annual temperature on Ellesmere Island during the Pliocene was about 34 degrees Fahrenheit (19 degrees Celsius) hotter than it is today, levels of the greenhouse gas carbon dioxide were only slightly higher than present.

Elevated Arctic temperatures during the Pliocene are thought to have been driven by the transfer of heat to the polar regions and perhaps by decreased reflectivity of sunlight hitting the Arctic due to a lack of ice, said Ballantyne. One big question is why the Arctic was so sensitive to warming during this period, he said.

Multiple feedback mechanisms have been proposed to explain the amplification of Arctic temperatures, including the reflectivity strength of the Sun on Arctic ice and changes in vegetation seasonal cloud cover, said Ballantyne. “I suspect that it is the interactions between these different feedback mechanisms that ultimately produce the warming temperatures in the Arctic.”

Presently, Arctic sea ice is declining at a rate of 11.2 percent per decade according to the National Snow and Ice Data Center.

Some climate change experts are forecasting that the Arctic summers will become ice-free within a decade or two.

Copyright Environment News Service (ENS) 2010. All rights reserved.

Original article here

Arctic oscillation – what is it?

The extreme or, rather, unusually low temperatures this winter in Europe ad North America is being explained by some as an effect of  “Arctic oscillation”. But what is this phenomenon?
Hang on as we turn to the  National Snow and Ice Data Center (US) for some answers:

The Arctic Oscillation
The Arctic Oscillation refers to opposing atmospheric pressure patterns in northern middle and high latitudes.

The oscillation exhibits a “negative phase” with relatively high pressure over the polar region and low pressure at midlatitudes (about 45 degrees North), and a “positive phase” in which the pattern is reversed. In the positive phase, higher pressure at midlatitudes drives ocean storms farther north, and changes in the circulation pattern bring wetter weather to Alaska, Scotland and Scandinavia, as well as drier conditions to the western United States and the Mediterranean. In the positive phase, frigid winter air does not extend as far into the middle of North America as it would during the negative phase of the oscillation. This keeps much of the United States east of the Rocky Mountains warmer than normal, but leaves Greenland and Newfoundland colder than usual. Weather patterns in the negative phase are in general “opposite” to those of the positive phase, as illustrated below.

Over most of the past century, the Arctic Oscillation alternated between its positive and negative phases. Starting in the 1970s, however, the oscillation has tended to stay in the positive phase, causing lower than normal arctic air pressure and higher than normal temperatures in much of the United States and northern Eurasia.

Arctic Oscillation

Effects of the Positive Phase      |     Effects of the Negative Phase
of the Arctic Oscillation                    of the Arctic Oscillation

(Figures courtesy of J. Wallace, University of Washington)