Study: Declining sea ice not good for polar bears

Posted on March 20, 2013 by Bob Berwyn
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A detailed new study shows how declining sea ice affects polar bear migration. Photo courtesy USFWS.

Research may help explain declines in cub production and body condition

By Summit Voice

SUMMIT COUNTY — A 10-year study of polar bears around western Hudson Bay offers new clues to how the predators will cope with global warming.

The research, published in the British Ecological Society’s Journal of Animal Ecology, focused on how sea ice conditions drive polar bears’ annual migration on and off the ice.

Polar bears have adapted to the annual loss of sea ice by migrating onto land each summer. While there, they cannot hunt seals and must rely on fat reserves to see them through until the ice returns.

“The data suggest that in recent years, polar bears are arriving on shore earlier in the summer and leaving later in the autumn,” said Dr. Seth Cherry, of the University of Alberta. “These are precisely the kind of changes one would expect to see as a result of a warming climate and may help explain some other studies that are showing declines in body condition and cub production.” (more…)

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Climate: German researchers document dramatic Arctic ecosystem changes linked with melting sea ice

Posted on February 20, 2013 by Bob Berwyn
On a voyage

On a voyage to the central Arctic Ocean, German researchers documented significant changes to marine ecosystems linked with melting Arctic sea ice. Photo courtesy Alfred Wegener Institute.

Massive algae blooms change composition of sea floor food chain

By Summit Voice

SUMMIT COUNTY — Arctic Ocean ecosystems are sure to change in as-yet unexpected ways as sea ice continues to shrink. This summer, German Polar researchers and microbiologists documented one of those changes, observing an unprecedented bloom of ice-loving algae on patches of thin summer ice.

The researchers hypothesized three years ago that ice algae could grow faster under the thinning sea ice of the Central Arctic. This past summer’s observations support the hypothesis: The ice algae were responsible for almost half of the primary production in the Central Arctic Basin. The paper is published in the journal Science.

“We were able to demonstrate for the first time that the warming and the associated physical changes in the Central Arctic cause fast reactions in the entire ecosystem down to the deep sea,” said Lead researcher Dr. Antje Boetius, of the Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research. (more…)

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Global warming: What are the options for polar bears?

Posted on February 7, 2013 by Bob Berwyn
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Are polar bears on the brink?

“It’s a fact that early sea ice break-up and late ice freeze-up and the overall reduction in ice pack are taking their toll.”

By Summit Voice

FRISCO — Despite reports of increases in isolated polar bear populations, the species as a whole is still imperiled by the rapid, steady rise in Arctic temperatures and shrinking areas of sea ice. Just one unexpected jump in Arctic warming trends could push the predators toward extinction, according to a new warning from a team of scientists led by University of Alberta polar bear researcher professor Andrew Derocher.

The new paper in the journal Conservation Letters is framed as a policy perspective, urging countries with polar bear populations to consider the long-term implications of climate change.

“It’s a fact that early sea ice break-up and late ice freeze-up and the overall reduction in ice pack are taking their toll,” Derocher said. “We want governments to be ready with conservation and management plans for polar bears when a worst case climate change scenario happens.” (more…)

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New study tracks emperor penguin sea ice habits

Posted on November 22, 2012 by Bob Berwyn

Sea ice critical for rests during long foraging treks

These are emperor penguins near the sea.
Credit: Photo credit: Katsufumi Sato (Atmosphere and Ocean Research Institute, The University of Tokyo)

By Summit Voice

SUMMIT COUNTY — Climate-related shifts in ice around Antarctica have already been implicated in the disappearance of at least emperor penguin colony, but researchers have not been sure exactly how sea ice figures in to their life cycle.

In a new study, researchers show how the birds use sea ice to rest during long foraging periods. The life cycle of the emperor penguins takes place in an exquisite balance with the rhythms of ice formation. Courtship, egg laying and incubation occur during winter, followed by hatching, brooding and crèche formation during spring and early summer. Both parents tend the chicks until they fledge, generally in late spring and early summer (November and December), when the ice breaks up into floes that drift with the wind and currents.

Unlike other species, like Adelie penguins, emperor penguins spent much more time diving for food, and only used about 30 percent of their time at sea to take short breaks to rest on sea ice. The birds did not travel for long distances on the ice, or use it for other activities. The study also suggests that these short rest periods on sea ice may help the penguins avoid predators such as leopard seals. (more…)

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Climate: Arctic sea ice expanding, but impacts from record-low levels could still be felt the next few months

Posted on October 19, 2012 by Bob Berwyn

Antarctic sea ice extent remains above average

Antarctic sea ice has dwindled from a record-high extent in October but remains above average for this time of year. Bob Berwyn photo.

By Summit Voice

SUMMIT COUNTY — Although Arctic sea ice cover has grown quickly the past few weeks, the extent remained below the previous record low for a full 40 days before recently climbing back to near that 2007 level on Oct. 6.

According to the National Snow and Ice Data Center, sea ice extent had grown to about 2 million square miles as of Oct. 15, which is about 1.35 million square miles below the 1979 to 2000 mean. Ice extent is growing by about 38,600 square miles per day, expanding southward at the ice edge, as well as northward from the Arctic continental coasts

Despite the rapid growth of the sea ice extent in the past few weeks, vast areas of open water remain, resulting in a massive heat transfer from the ocean to the atmosphere, with potential impacts on atmospheric circulation in high latitudes, as the heat buildup over the Arctic changes pressure gradients in the region. (more…)

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Climate: Antarctic research season starts with aerial surveys

Posted on October 18, 2012 by Bob Berwyn

NASA’s Operation IceBridge surveys Thwaites Glacier and Bellinghausen Sea

This NASA photo shows the calving front of Thwaites Ice Shelf looking at the ice below the water’s surface. Note how the water acts as a blue filter.

By Summit Voice

SUMMIT COUNTY — As Arctic sea ice melted away to a new record-low level this summer, global warming deniers tried to deflect attention from the meltdown by emphasizing the growth in Antarctic sea ice.

Of course, the increase in Antarctic sea ice is small compared to the loss of Arctic ice, and there are other hints that Antarctica is set to experience some major changes. In coming decades, entire ice shelves along the coast may crumble into the sea, potentially contributing significantly to sea level rise.

To measure those impending changes, NASA has been doing extensive aerial surveys in Antarctica with Operation IceBridge, and this year’s flying season began productively with a land ice survey of Thwaites Glacier and a sea ice flight over parts of the Bellingshausen Sea. (more…)

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Climate: Ice-free Arctic ahead?

Posted on September 21, 2012 by Bob Berwyn

A warming Arctic is changing the configuration of the jet stream, which affects mid-latitude weather. GRAPHIC COURTESY NOAA.

Researchers cautious about predicting the demise of Arctic ice

By Bob Berwyn

SUMMIT COUNTY — Despite a steady trend of melting Arctic sea ice, experts with the National Oceanic and Atmospheric Administration aren’t yet willing to make any predictions as to when the region will be completely ice-free during the summers.

The National Snow and Ice Data Center earlier this week said that the melt bottomed out in mid-September at new record low extent, but lingering thick, multi-year ice along the north coast of Greenland may persist for decades to come, preventing a total melt-out, said  NSIDC ice researcher Walt Meier, speaking during a Sept. 20 teleconference.

That may lead to a plateau at some during what’s been somewhat sensationally described as the Arctic ice death spiral, Meier said, adding that conditions are so variable from year to year that it’s hard to predict the timing. (more…)

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Climate: Arctic sea ice now in ‘uncharted territory’

Posted on September 19, 2012 by Bob Berwyn

Arctic sea ice extent for September 16, 2012 was 3.41 million square kilometers (1.32 million square miles). The orange line shows the 1979 to 2000 median extent for that day. The black cross indicates the geographic North Pole. Graphic courtesy NSIDC.

Low point reached Sept. 16; 293,000 square miles less ice than previous record in 2007

By Summit Voice

FRISCO — More than 4.5 million square miles of Arctic sea ice has melted away in the past six months, with the overall extent dipping 18 percent below the previous record low, set in 2007.

The ice appears to have reached its minimum on Sept. 16, according to the National Snow and Ice Data Center, and will grow once again for the next six months as long, cold nights prevail above the Arctic Circle.

The record ice loss came despite the fact that the region didn’t see extreme warmth. Temperatures were above-average, but colder than in 2007, when the previous record low ice extent was reached.

The six lowest seasonal minimum ice extents in the satellite record have all occurred in the last six years, 2007 to 2012. (more…)

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Global warming to disrupt Arctic species migration

Posted on September 16, 2012 by Bob Berwyn

Arctic foxes. Photo courtesy Yvonne Cox.

Study shows impacts to Arcit fox populations

By Summit Voice

FRISCO — It’s very likely that human-caused global warming will disrupt the natural cycles of glaciation that have prevailed in recent millennia, and that could spell trouble for species that have relied on bridges of sea ice to maintain genetic diversity.

That includes Arctic foxes that were able to colonize Iceland during the Little Ice, according to research by scientists at the UK’s Durham University, who said that Arctic foxes were able to migrate to Iceland from Russia, North America and Greenland when such a bridge formed, between 200 and 500 years ago.

Iceland’s population of about 10,000 arctic foxes is not at risk, the researchers said, but explained that increasing isolation from the rest of the Arctic, caused by warmer temperatures and a lack of sea ice, could further differentiate the island’s population from their mainland relatives. (more…)

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Climate: Seasonal Arctic ice cap meltdown begins

Posted on May 5, 2012 by Bob Berwyn

 Arctic sea ice starting melting quickly in late April

Sea ice extent in Antarctica has been above average during the Austral summer.

Antarctica. IMAGE COURTESY NASA.

By Summit Voice

SUMMIT COUNTY — After staying near average levels during much of April, the Arctic sea ice extent started a rapid decline late in the month, marked by the meltdown of freshly formed thin ice that can’t persist from year to year.

The linear rate of decline for April ice extent over the satellite record is 2.6 percent per decade.

For the month, the ice extent averaged 5.69 million square miles. Because of the very slow rate of ice loss through the last half of March and the first three weeks of April, ice extent averaged for April ranked close to average out of 34 years of satellite data, according to the latest update from the National Snow and Ice Data Center. (more…)

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