Antarctic clams may take a hit from global warming

Posted on April 19, 2013 by Bob Berwyn

Study shows climate change may affect overall population numbers

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Changes in Antarctic clam populations could have a ripple effect on other species in the region like these blue-eyed cormorants in the South Shetlands. Bob Berwyn photo.

By Summit Voice

FRISCO — Warming ocean temperatures and increased glacial outflow around Antarctica may have a big impact on clams living on the ocean floor. Younger clams try to move away when they sense warmer temperature or reduced oxygen levels, but older clams stay put.

The findings by a team of British and German scientists indicate how climate change may affect biodiversity in the region, suggesting that the overall population of Antarctic clams may dwindle, since it’s the older animals that reproduce.

“Our study shows that the physiological flexibility of young clams diminishes as they get older. However, the species has evolved in such a way that the fittest animals, that can tolerate life in an extreme environment, survive to reproduce into old age,” said Doris Abele, of the Alfred Wegener Institute in Germany. “Climatic change, affecting primarily the older clams, may interfere with this evolutionary strategy, with unpredictable consequences for ecosystems all around Antarctica.” (more…)

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Climate: Antarctica surface melting speeds up

Posted on April 14, 2013 by Bob Berwyn

Ice core study shows rapid pace of change along Antarctic Peninsula

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Warmer summer temperatures along the Antarctic Peninsula are starting to take a toll on ice and snow in the region. Bob Berwyn photo. (Dundee Island).

By Bob Berwyn

FRISCO — Careful study of a 1,200-foot long ice core sample spanning 1,000 years suggests that summer ice melt in parts of the Antarctic Peninsula region has intensified almost tenfold. About 5 percent of the annual snowfall has been melting in recent years, compared with only about 0.5 percent during the coolest phase (about 600 years ago) of that 1,000-year span.

“This is the first time it has been demonstrated that levels of ice melt on the Antarctic Peninsula have been particularly sensitive to increasing temperature during the 20th Century,” said Dr. Nerilie Abram, a climate researcher at Australian National University who studied the ice core from James Ross Island.

Most of the increased melting occurred during the past half-century, corresponding with the era of increasing greenhouse gas emissions and a remarkable warmup around the peninsula and some other parts of Antarctica. Borehole temperature estimates from the West Antarctic Ice Sheet also indicate rapid acceleration of West Antarctic warming during the past two decades. (more…)

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Morning Photo: Antarctic Peninsula

Posted on March 28, 2013 by Bob Berwyn

Researchers confirm dramatic meltdown

Dawn in the Antarctic Sound.

Dawn in the Antarctic Sound.

FRISCO — A new study once again confirms the rapid warmup of the Antarctic Peninsula, due to shifting wind patterns. The increased temperatures are manifesting in a longer melt season, with potentially huge consequences for ecoystems and physical features, including coastal ice shelves, which are already cracking and crumbling. There have already been big shifts in penguin populations, and krill, at the base of the Southern Ocean food web, is also at risk. Read the story to learn more, check out more Summit Voice coverage of Antarctica here.

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A lone chinstrap penguin on an iceberg in the Antarctic Sound.

(more…)

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Antarctic Peninsula’s melt season lengthens dramatically

Posted on March 28, 2013 by Bob Berwyn

Warmer temps linked with ice shelf break-ups

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A longer melt season along the Antarctic Peninsula has consequences for wildlife — and for the long-term fate of the coastal ice shelves. Bob Berwyn photo.

By Summit Voice

SUMMIT COUNTY — The melt season on the Antarctic Peninsula is growing longer — in some cases it has doubled, and several major ice shelf breakup events in the region coincided with longer than usual melt seasons, according to a a new study that analyzed data from 30 weather stations.

“We found a significant increase in the length of the melting season at most of the stations with the longest temperature records,” said Dr. Nick Barrand, who carried out the research while working for the British Antarctic Survey. “At one station the average length of the melt season almost doubled between 1948 and 2011,” said Barrand, who now works for the University of Birmingham. (more…)

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Study finds link between El Niño and warming along the Antarctic Peninsula during parts of the Holocene

Posted on January 23, 2013 by Bob Berwyn

Ocean-driven warming along western Antarctic Peninsula may be partly driven by natural climate variability

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Ice remnants along the shore of the Antarctic Peninsula. Bob Berwyn photo.

By Summit Voice

SUMMIT COUNTY — Temperature oscillations in the tropical Pacific have historically had a significant effect on the climate of the western Antarctic Peninsula, according to scientists who studied a 12,000-year fossil record to measure how much glacial ice melted into the sea during that span.

The research is important because the western Antarctic Peninsula is one of the fastest warming regions on the planet, and the fastest warming part of the Southern Hemisphere. The ice sheets of the region may be vulnerable to collapse, and would raise sea level by several meters if the melt.

The study, led by Cardiff University researchers, measured oxygen isotopes in microscopic marine algae fossils to trace glacial ice entering the ocean along the western Antarctic Peninsula. Based on the data, the study concluded that the atmospheric temperatures had a bigger factor than oceanic circulation on warming along the western Antarctic Peninsula than oceanic circulation in the late Holocene (from 3,500-250 years ago). (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: Topography affects rate of ice sheet retreat

Posted on October 17, 2012 by Bob Berwyn

Antarctica study suggests shape of channels beneath ice can slow or temporarily halt retreat of ice sheets

Despite steady global warming, ice sheet retreat may slow or even stop temporarily, based on the shape of the ground beneath the ice. Bob Berwyn photo.

By Summit Voice

SUMMIT COUNTY — Even as global warming shrinks many of the world’s major ice sheets, new research suggest that the underlying topography can significantly influence how fast they retreat, and in some cases even halt temporarily during long phases of climate warming.

The researchers reached their conclusions after studying the landscape of the seafloor in Marguerite Bay, in the Antarctic Peninsula. They saw that, during a rapid phase of recession 13,000 years ago, retreat paused many times.

Computer models showed that ice dragged on the sides of the channel more where it was narrow, causing retreat to slow and in places temporarily stop for decades to centuries before retreat continued. (more…)

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Study: Tourism not a factor in Antarctic penguin decline

Posted on September 15, 2012 by Bob Berwyn

Steep drops in chinstrap, Adélie penguin populations linked with global warming, decline of krill

A lone chinstrap penguin on an ice floe near Brown Bluff, Antarctica. Photo by Bob Berwyn.

By Bob Berwyn

FRISCO — Chinstrap penguin populations around Antarctica — including a major colony at Baily Head on Deception Island — are dwindling, and some have even blinked out in what scientists are calling colony collapse.

But tourism is not a big factor in the decline, according to researchers who compared penguin population trends at heavily visited sites with other spots that aren’t on the Antarctic tourism circuit.

Adélie penguin populations are also dropping regionally. Both species are offshore foragers, so loss  of sea ice and changes in krill populations — driven by global warming — are suspected be the primary causes. The Antarctic Peninsula, including the South Shetland archipelago, is warming faster than almost any other part of the planet.

It’s also possible that rebounding humpback whale populations, as well as commercial fishing, are affecting krill distribution to some degrees, but researchers haven’t yet been able to pinpoint those impacts accurately. (more…)

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Climate: Antarctic ice shelves poised for collapse

Posted on August 23, 2012 by Bob Berwyn

Gradual warming over centuries set stage for disintegration

New ice core studies may help predict the fate of Antarctic Peninsula ice shelves. Bob Berwyn photo.

By Summit Voice

SUMMIT COUNTY — A new set of ice cores from James Ross Island in the Antarctic are helping to shed some light on long-term climate change in the reason.

After examining the 15,000-year climate record in the ice cores, the research team concluded that the rapid warming of this region over the last 100 -years has been unprecedented and came on top of a slower natural climate warming that began around 600 years ago.

Several centuries of gradual warming set the stage for the breakup of Antarctic Peninsula ice shelves that started in the 1990s, after regional temperatures soared in the past few decades. the Antarctic Peninsula is one of the fastest-warming areas of the globe — average temperatures from meteorological stations near James Ross Island have risen by nearly 2 degrees Celsius in the past 50 years. (more…)

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Global warming: Ice loss threatens emperor penguins

Posted on June 25, 2012 by Bob Berwyn

Emperor penguin and chick. PHOTO COURTESY BRITISH ANTARCTIC SURVEY.

By Bob Berwyn

SUMMIT COUNTY — Not long after biologists with the British Antarctic Survey documented the disappearance of an emperor penguin colony, a new research effort also suggests that climate change may drastically reduce Antarctic habitat for the iconic ice-dwelling birds.

Focusing on a long-studied colony in Terre Adélie, scientists with the Woods Hole Oceanographic Institution concluded that the number of breeding pairs at the colony could drop by 80 percent by the end of the century.

“The projected decreases in sea ice may fundamentally alter the Antarctic environment in ways that threaten this population of penguins,” said NCAR scientist Marika Holland, a co-author of the study.

Another recent study by the British Antarctic Survey suggested that emperor penguin populations are much higher, perhaps twice as large, as previously believed. Last November, conservation groups petitioned the U.S. Fish and Wildlife Service to list emperor penguins under the Endangered Species Act. (more…)

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