Thread: Melting Greenland Ice Has Consequences

October 12, 2012 12:01 pm

Melting Greenland Ice Has Consequences

An iceberg floats off the coast of Greenland. Photo: Christine Zenino

In a new study lead by Jonathan Bamber, scientists found that, over the past few decades, the melting of Greenland glaciers has been feeding an anomalous spike in North Atlantic freshwater. If it continues as it has been, in the coming years the spike will rival the effects of the Great Salinity Anomaly—a bulge of fresh water that can affect the circulation patterns of the whole Atlantic Ocean.

Here’s the background: In the late 1960s, the first Great Salinity Anomaly (GSA) formed off the eastern shores of Greenland. Formed by a spike in Arctic ice melt, the event led to the formation of a thin sheet of fresh water that floated on the typically cold, salty waters of the north Atlantic Ocean. Over the subsequent years, the anomaly drifted about the North Atlantic, first around the southern tip of Greenland, then off to the coast of Canada, then up and around, along the Gulf Stream to northern Europe. As it traveled, the freshwater pool acted as a cap, limiting the interaction between the air and the ocean.

According to Oceanus, the magazine of the Woods Hole Oceanographic Institution, “[t]he GSA acted as a sort of moving blanket, insulating different parts of the deep ocean from contact with the atmosphere as it moved around the gyre.” Similar events have happened in the decades that followed, and scientists have found that they can cause unusual temperature patterns for the United States and northern Europe, and may even affect fish populations.

In the new study, researchers found found that the flow of fresh water from Greenland into the North Atlantic has been increasing since the 1990s. According to Michael Marshall for New Scientist, the melting Greenland ice could even make it so that the Atlantic Ocean is less able to draw carbon dioxide out of the atmosphere, creating the potential for a feedback loop that would further drive global warming.

The polar oceans are among the world’s most important carbon sinks, taking in carbon dioxide from the air and trapping it in their depths – and that could change as a result of the freshwater flux. Curry says Greenland’s fresh water will remain at the surface, since the weakened [Atlantic Meridional Overturning Circulation] will be slow to carry it to the bottom. That also means that once this fresh water has absorbed as much carbon dioxide as it can hold, it will not be replaced at the surface by carbon-dioxide-free water that could absorb more of the gas.

More from Smithsonian.com:
Why 97 Percent Of Greenland’s Icy Surface Just Melted

Melting Greenland Ice Has Consequences | Smart News

OpEd: Melting ice catastrophic for polar bears

Russian expert predicts end of mighty mammals within decades

By Matthew Fisher, Postmedia NewsOctober 12, 2012

While Arctic sea ice reached a record low this summer, it is not widely known that almost all the ice that melted or drifted away was on the Russian, not the Canadian and Greenlandic side of the great northern sea.

One immediate consequence has been further grief and peril for Russia's already seriously distressed polar bear population.

"It is worse for Russian polar bears than the bears in Canada or Greenland because the pack ice is retreating much faster in our waters," said Nikita Ovsyannikov, deputy director of Russia's polar bear reserve on Wrangel Island in the Chukchi Sea to the northwest of Alaska. "The best habitat is quickly disappearing. It is extreme.

"What we are seeing right now is very late freezing. Our polar bear population is obviously declining. It used to be that new ice was thick enough for them to walk on in late October. It now will happen much later."

Figuring out how many bears still survived on and near the Chukchi Sea - home to the largest of Russia's four polar bear populations - was difficult because they were spread across such a vast area, said the zoologist, who has spent his life studying bears in the High Arctic.

He guessed that the number of bears around the Chukchi Sea, which also sometimes migrate in small numbers to western Alaska, had dropped over the past three decades from "about 4,000 to no more than 1,700 at best."

The retreating ice that has placed many Russian bears in a catastrophic situation has turned out to be a boon to the country's Arctic mariners. Taking advantage of the unprecedented sea conditions, dozens of freighters, including several mammoth 170,000-dead weight-ton tankers, have used the Northeast Passage during the summer and fall of 2011 and again this year to bring as much as 120,000 tons of liquefied natural gas at a time from western Russia through the Bering Strait to China.

With no ice yet present near the Russian coast, there has even been talk that it might be possible to keep what is called the "Northern Sea Road" open until January.

The situation was so grave this year that sea ice that had already melted by July is not expected to return until as late as next January in the waters above the continental shelf where Russian polar bears traditionally spend a good part of their lives hunting from drifting ice for ring seals.

The explanation for the sudden, further decline in sea ice this summer was unusually low pressure in the Eurasian coastal seas and in the Beaufort Sea and East Siberian Sea, combined with unusually high pressure centred over Greenland and the North Atlantic, according to the U.S.-based National Snow and Ice Data Center. Air temperatures across the Arctic rose by as much as three degrees Celsius this summer.

With no drifting pack ice near the shore to hunt from, Russia's polar bears have faced a stark choice.

They either must go far out to sea on pack ice that has been drifting away from the coast in the late spring, or forage for food as best they can on Russia's few Arctic islands or along the coast.

However, venturing far from land presents special problems for female bears who traditionally build their hibernation and birthing dens on land.

"Making a den on drifting ice is much more difficult," Ovsyannikov said. "One reason is that there is a greater chance that other bears will disturb them there.

"But some females are den-ning on the drifting ice because the ice is freezing up again so late in the fall that they cannot get back to land. We have evidence of this."

There will be no polar bears anywhere in the wild within 20 to 25 years, Ovsyannikov predicted.

However, it is wrong to think that their "extermination" is only happening because of global warming, he said. Another key factor is that warmer air and sea temperatures have forced polar bears to spend more time on land where "too many of them were being shot and poached."

Other species under threat include seals, walrus, Arctic fox and snowy owls, he said.

The big cargo ships transiting to Asia using the Northeast Passage pose another potential danger. Any spill will cause great harm across the north because oil dissolves slowly in cold water and is notoriously difficult to clean up if it comes into contact with drifting ice or ice that is attached to land.

"It is inevitable that economic development will continue," Ovsyannikov said. "So it is up to us to take as many precautions as possible because a shipping accident in the Arctic would be an absolute disaster for the entire ecosystem."

OpEd: Melting ice catastrophic for polar bears