Climate: Does El Niño drive West Antarctic warming?

Posted on April 17, 2013 by Bob Berwyn

Ice cores suggest current climate is in the natural range of variability

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Climate scientists track Antarctic changes, Bob Berwyn photo.

By Summit Voice

FRISCO — Ice cores from West Antarctica spanning the last 2,000 years suggest that recent warming and glacier loss in the region is comparable to other warm periods during that span.

Most of the recent warming may be related to powerful El Niño phases in the tropical Pacific in the 1990s, said University of Washington researcher Eric Steig. The ice core record shows similar temperature spikes in the 1830s and 1940s, he said, adding that the recent warming  cannot be attributed with confidence to human-caused global warming.

Steig built on previous research showing that rapid thinning of Antarctic glaciers was accompanied by rapid warming and changes in atmospheric circulation near the coast. The new study suggests that the 1990s were not all that different from some of those earlier warm spells. (more…)

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New ice core data from Greenland offers chilling clues about the direction of Earth’s climate

Posted on January 24, 2013 by Bob Berwyn

‘Our kids and grandkids are definitely going to look back and shake their heads at the inaction of this country’s generation’

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For several days in July 2012, the surface of the Greenland ice sheet melted over a larger area than at any time in more than 30 years of satellite observations. An estimated 97 percent of the ice sheet surface had thawed by July 12, with satellite data providing a picture of an extreme melt event about which scientists are very confident. Graphic courtest Nicolo E. DiGirolamo, SSAI/NASA GSFC, and Jesse Allen, NASA Earth Observatory.

By Summit Voice

FRISCO — Last summer’s unusual melting at the surface of Greenland’s ice cap has a historic precedent, but you have to go back more than 100,000 years, to an extremely warm interglacial period of Earth’s history, to find it, according to an international science team’s  analysis of ice core samples spanning millennia of climate history.

The new study, published this week in Nature, offers clues about where the planet is headed in terms of increasing greenhouse gases and rising temperatures, according to CU-Boulder ice core expert Jim White — another researcher whose detailed knowledge of climate science has led him to advocate for reductions in greenhouse gas emissions.

“Unfortunately, we have reached a point where there is so much carbon dioxide in the atmosphere it’s going to be difficult for us to further limit our impact on the planet,” White said. “Our kids and grandkids are definitely going to look back and shake their heads at the inaction of this country’s generation. We are burning the lion’s share of oil and natural gas to benefit our lifestyle, and punting the responsibility for it.” (more…)

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Climate: Study suggests recent West Antarctic glacier changes are nearly unprecedented

Posted on January 19, 2013 by Bob Berwyn

Data to help refine sea level rise forecasts

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West Antarctica‘s Pine Island Glacier. Photo courtesy European Space Agency.

By Summit Voice

FRISCO — After studying the paleoclimate record of West Antarctica, an international team of scientists say some of the recent observed changes in the Pine Island and Thwaites glaciers may well be exceptional and are unlikely to have happened more than three or four times in the last 10,000 years.

Radiocarbon dates of tiny fossilized marine animals found in Antarctica’s seabed sediments offer new clues about the recent rapid ice loss from the West Antarctic Ice Sheet and help scientists make better predictions about future sea-level rise.  This region of the icy continent is thought to be vulnerable to regional climate warming and changes in ocean circulation. (more…)

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Global warming research eyes ‘runaway’ ice melt

Posted on December 31, 2012 by Bob Berwyn

Sea level forecasts may be way off

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Will there be runaway ice sheet melting? Bob Berwyn photo.

By Summit Voice

FRISCO — Most climate models are probably underestimating the rate of sea level rise expected during the next few decades, according to some of the latest research that tries to quantify how much ice may melt off the Greenland and Antarctica ice sheets.

A Dec. 26 update by James Hansen and Makiko Sato warns that melting of those ice sheets could increase sea level rise exponentially higher than most existing forecasts, potentially inundating coastal cities around the world with several feet of water by the end of the century.

The short paper discusses the linearity assumptions in most existing climate models and suggests that, if greenhouse gas emissions continue unchecked, “the climate forcing will be so large that non-linear ice sheet disintegration should be expected and multi- meter sea level rise not only possible but likely.” (more…)

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Global warming: Study suggests temperatures in West Antarctica rising much faster than previously estimated

Posted on December 24, 2012 by Bob Berwyn

New data fills gap in Antarctic climatology

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A new evaluation of temperatures records from West Antarctica raises concerns about impacts to sea level rise. Bob Berwyn photo.

By Summit Voice

FRISCO — A new analysis of temperature records from a research station in West Antarctica suggests that temperatures in the remote region have climbed steeply in the last half-century, by as much as 4.3 degrees since 1958.

The findings, published in the most recent issue of Nature Geoscience, heighten concerns about the future contribution of Antarctica to sea level rise, because researchers say the West Antarctic Ice Sheet is especially sensitive to climate change.

Since the base of the ice sheet rests below sea level, it is vulnerable to direct contact with warm ocean water. Its melting currently contributes 0.3 mm to sea level rise each year—second to Greenland, whose contribution to sea level rise has been estimated as high as 0.7 mm per year, according to Ohio State University doctoral student Julien Nicolas. (more…)

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Climate: New clues for West Antarctic ice sheet melting

Posted on December 7, 2012 by Bob Berwyn

New data shows warm ocean currents melting the ice from below

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Antarctic sea ice has expanded slightly in recent years, but the continental ice shelves are losing mass. Bob Berwyn photo.

By Summit Voice

FRISCO — New data from sensors in the Amundsen Sea suggest more strongly than ever that warm ocean currents are causing extensive ice loss from the West Antarctic Ice Sheet.

Ice in the area is melting faster than expected and could contribute significantly to sea level rise, but there’s been very little data from the region. The latest observations by oceanographers from the University of Gothenburg (Sweden) were recently published in the journal Nature Geoscience.

Previous research by the British Antarctic Survey showed that rising air temperatures in the region will break down a hydrological boundary of cold water, allowing warmer water to infiltrate beneath the ice. (more…)

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Climate: Arctic and Antarctic ice melt are accelerating

Posted on November 30, 2012 by Bob Berwyn

Greenland and Antarctica are now losing more than three times as much ice as they were in the 1990s

Antarctic sea ice may be growing, but ice sheets on the frozen continent’s edge are losing mass and contributing to sea-level rise. Bob Berwyn photo.

By Summit Voice

SUMMIT COUNTY — Climate scientists say they’re closer to pinpointing exactly how much of Greenland’s and Antarctica’s ice is melting, and after producing the most accurate assessment of ice losses to-date, a team of satellite experts say they’ve ended 20 years of uncertainty about how much that melting ice contributes to global sea level rise.

According to the landmark study, published on Nov. 30 in the journal Science, the that melting has contributed 11.1 millimeters to global sea levels since 1992. This amounts to 20 percent of all sea level rise during the survey period. About two thirds of the ice loss was from Greenland, and the remainder was from Antarctica.

Together, Greenland and Antarctica are now losing more than three times as much ice (equivalent to 0.95 mm of sea level rise per year) as they were in the 1990s (equivalent to 0.27 mm of sea level rise per year). The rate of melting increased dramatically in the late 1990s. (more…)

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British team set to drill deep into subglacial Antarctic lake

Posted on September 7, 2012 by Bob Berwyn

Sampling of lake will provide climate, evolutionary clues

British camp deep field, Lake Ellsworth. PHOTO COURTESY BRITISH ANTARCTIC SURVEY.

By Summit Voice

SUMMIT COUNTY — For many years, scientists have wondered if life in some form has persisted at the very margins of the Earth’s enviroment, perhaps tucked two miles deep beneath the surface of Antarctica’s ice sheets.

After recent discoveries of organisms that can survive in the super-heated environment around deep-sea volcanic vents, or in near-boiling geothermal pools in Yellowstone, it might not be such a stretch to imagine that some equally astounding form of life may exist in frozen parts of the world, but we just don’t know, at least not yet.

Some of the answers may be forthcoming from the results of an expedition by the British Antarctic Survey to drill into the subglacial Lake Ellsworth, on the West Antarctic Ice Sheet. Learn more at the  Lake Ellsworth project website, visit the researchers on the Lake Ellsworth Facebook page and follow the expedition on Twitter.

Their quest is to reveal vital secrets about the Earth’s past climate and discover life forms that may live in subglacial Lake Ellsworth on the West Antarctic Ice Sheet. Researchers say their findings may even offer clues as to whether life is possible on other planets.

Lake Ellsworth is one of 387 subglacial lakes that havebeen discovered beneath Antarctica’s vast ice sheet. The most well-known of these is Lake Vostok in East Antarctica. A Russian team hopes to penetrate and collect samples from Vostok. (more…)

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Global warming: Organic sediments under Antarctic ice sheets may become a huge source of heat-trapping methane

Posted on August 30, 2012 by Bob Berwyn

Sub-ice environments are biologically active and converting organic material to methane

Antarctica is a potentially vast source of heat-trapping methane. Photo by Bob Berwyn.

By Summit Voice

SUMMIT COUNTY — Climate researchers have long warned that stores of organic material in the Arctic will release vast amounts of heat-trapping methane as the atmosphere warms.

Now, a new study shows that Antarctica is another potentially huge source of methane. As much as 50 percent of the West Antarctic ice sheet may be covering old organic matter in sedimentary basins — and that organic matter may have been converted to methane by micro-organisms living under oxygen-deprived conditions.

The methane could be released to the atmosphere if the ice sheet shrinks and exposes these old sedimentary basins, the study concludes. (more…)

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New study suggests climate link between Arctic and Antarctica

Posted on June 25, 2012 by Bob Berwyn

Sediment core record from remote Siberian lake shows unusually warm Arctic periods coincided with deglaciation of West Antarctica

Sea ice is vanishing around the Antarctic Peninsula, and there are signs the West Antarctic ice sheet may be prone to disintegration. Photo by Bob Berwyn.

Rifts along the northern shear margin of Pine Island Glacier (upper right of image). Photo courtesy Michael Studinger, NASA’s Operation IceBridge.

By Bob Berwyn

SUMMIT COUNTY — Researchers studying sediment cores dating back nearly 3 million years found evidence that the Arctic has experienced several intensely warm climate intervals, and that there may be a link between those periods and episodes of dramatic changes in the West Antarctic ice sheet.

“We found eight warm intervals … the majority relatively early in the Quarternary, when temperatures were 4 to 5 degrees Celsius warmer — as well as wetter — than during normal interglacial periods. They occurred irregularly, not following orbital cycles,” said Professor Martin Melles, of the University of Cologne, one of the lead researchers.

Other lead scientists include Julie Brigham-Grette of the University of Massachusetts Amherst; and Pavel Minyuk of Russia’s North-East Interdisciplinary Scientific Research Institute in Magadan.

“That’s what we know. Then we wanted to know the reasons for that. It can’t be explained by greenhouse gas variations or orbital variations, so we compared the interglacial warm intervals with other records,” said Melles, explaining that the warm intervals seemed to match up well with an Antarctic sediment core showing that the West Antarctic ice sheet disintegrated approximately during these same periods. (more…)

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