Climate: How fast are the ice caps really melting?

Long-term trends still unclear

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Ice floes melting on a warm spring day in the Antarctic Sound. Bob Berwyn photo.

By Summit Voice

FRISCO — Ice mass loss from both the Greenland Ice Sheet and Antarctica have doubled since accurate satellite-based gravity measurements started nine years ago, but it’s still not clear whether the melting will continue to accelerate at the same rate.

For now, the period of record is still too short to say, according to a new report published online this week in Nature Geosciences.

The research team was led by Bert Wouters, with the University of Bristol and included scientists with the GFZ German Research Centre for Geosciences.

The study concludes that predictions of the contribution of both ice shields to sea level rise through 2100 may be off by as much as 35 centimeters (about 13.8 inches) in either direction. Continue reading

Climate: How fast will Greenland’s glaciers melt?

Study shows topography is a key factor in controlling ice flow

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A giant iceberg that broke off the terminus of Greenland’s Petermann Glacier in July 2012 moves down the fjord toward the Nares Strait. Image courtesy NASA Earth Observatory.

A new study helps pinpoint how many icebergs may from as Greenland's glaciers are subjected to global warming. Photo courtesy British Antarctic Survey.

A new study helps pinpoint how many icebergs may from as Greenland’s glaciers are subjected to global warming. Photo courtesy British Antarctic Survey.

By Bob Berwyn

FRISCO — Greenland’s swift outflow glaciers are sensitive to warming air and ocean temperatures, but a new study published in the journal Nature indicates that the recent acceleration of glacial flow isn’t continuing at a linear rate.

The shape of the ground and seafloor beneath the glaciers is crucial in determining how they respond to climate change — how fast they move and how much they will contribute to sea level rise in coming decades.

“What we are saying is that we shouldn’t extrapolate the rate of the last 10 years into the future … If  you study these glaciers separately, they show different behavior,” said lead author Dr. Faezeh Nick, of the Université Libre de Bruxelles, describing the work done on the Petermann, Kangerdlugssuaq, Helheim and Jakobshavn Isbræ glaciers. Together, they drain about 22 percent of the Greenland ice sheet. Continue reading

Melting of Greenland’s ‘fringe’ glaciers adds to sea level rise

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The Greenland Today website tracks ice cap changes on a real-time basis. Click on the image for more information.

‘Local’ glaciers reacting faster to global warming than the main ice cap

By Summit Voice

SUMMIT COUNTY — Glaciers on the edge of Greenland are pouring at about 50 gigatons of water into the Atlantic every year. That’s about half the volume of Lake Geneva, one of Europe’s largest lake, and enough to account for about 10 percent of annual global sea level rise, according to a new study by Swiss and Danish scientists.

The research, published in Geophysical Research Letters, will help scientists improve the predictions of the future contribution of Greenland’s ice to sea-level rise.

The data could also be used by researchers maintaining the new Greenland Today website, which tracks the state of the ice cap on a real-time basis.

“The melting of ice on Greenland is known to be one of the major sources for global sea-level rise. Beside the large ice sheet, there are thousands of peripheral glaciers which are not connected to the ice sheet or can be separated from it due to the existence of ice divides,” said lead author Dr. Tobias Bolch, of the University of Zurich. “The area of those glaciers is about 50 times higher than the ice cover of the European Alps. Consequently, it is important to investigate not only the ice sheet but also these local glaciers,” he said. Continue reading

Greenland runoff may be a big source of iron

Runoff from melting Greenland glaciers may be a significant source of iron in the North Atlantic.

Runoff from melting Greenland glaciers may be a significant source of iron in the North Atlantic. Bob Berwyn photo.

Arctic meltdown may have consequences besides raising sea level

By Summit Voice

FRISCO — Melting Greenland glaciers may have an unforeseen side effect on ocean biology, as the surging runoff adds iron to the water, potentially fueling more plankton growth.

Glaciers have just recently been identified as a significant source of iron in a study by biogeochemists and glaciologists at Woods Hole Oceanographic Institution. The findings suggest that the influx of iron could increase as melting of the Greenland ice sheet escalates under a warming climate.

It’s long been known wind-blown dust and river runoff are source of iron, but meltwater runoff from glaciers and ice sheets was considered too dilute to carry much iron, although previous research has shown a strong correlation between the plankton blooms and the runoff from Greenland ice sheet. Continue reading

Climate: New study maps regional sea level rise variation

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A new study coordinated by the EU’s ice2sea program helps identify which parts of the world will be most affected by sea level rise in the coming decades.

Tropical Pacific to see the greatest increases, while relative sea level is likely to drop in some polar regions

By Summit Voice

FRISCO — Intensifying concerns about the potential for sea level rise to swamp low-lying Pacific island nations are justified, according to a new report in the Geophysical Research Letters journal. Western Australia, Oceania and the small atolls and islands in this region, including Hawaii, are at greatest risk, according to the new study from EU’s ice2sea program.

The results of the modeling mirror observational data that’s been collected by satellites in the past few decades, said David Vaughan, program coordinator for EU’s ice2sea program, which seeks to develop more accurate sea level rise predictions. Continue reading

Arctic sea ice near record low in January

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January sea ice extent has been dropping about 3 percent per decade, according to the NSIDC.

Northern hemisphere snow cover above average in December and January

By Summit Voice

FRISCO — Arctic sea ice remained well below average during January, about 400,000 miles below the 1979 to 2000 average for the month and the sixth-lowest during the satellite record. The last ten years (2004 to 2013) have seen the ten lowest January extents in the satellite record.

According to the latest update from the National Snow and Ice Data Center, January sea ice extent has been decreasing at abou 3.2 percent per decade. The largest areas of open water were around the Barents Sea and near Svalbard, northeast of Greenland. Sea ice extent was also below average along the east coast of Greenland. Continue reading

Climate: ‘Today’s flood is tomorrow’s high tide … ‘

‘The ocean is rising and it’s going to keep rising for quite some time’

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A NOAA aerial photo shows damage caused by superstorm Sandy along the New Jersey shoreline. Click on the photo to see before and after images on the NASA EO website.

By Bob Berwyn

FRISCO — What until recently was a mostly academic discussion about sea level rise is starting to hit home — literally —as Americans watch devastating storms like Katrina, Irene and Sandy engulf cities and fundamentally alter the shape of coastal areas.

“What is very clear is, the ocean is rising and it’s going to keep rising for quite some time. The difference from last time is, now, there are a lot of people living on the coast,” said Margaret Davidson, acting director of NOAA’s Office of Ocean and Coastal Resource Management. Davidson’s powerpoint presentation is online here, and a video of her presentation should also be posted at the same place soon.

The consequences of rising sea level are likely to be enormous, given that the majority of the country’s population lives along coastlines, and those coastal cities generate a huge percentage of the country’s economic wealth.

“How do we begin to think about that? We’ve never had to think about relocating large populations,” Davidson said, addressing an audience of broadcast meteorologists and climate scientists during the annual Glen Gerberg Weather and Climate Summit in Breckenridge. Continue reading

Global warming research eyes ‘runaway’ ice melt

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.” Continue reading

Environment: Study tracks historic changes in atmospheric acidity in Greenland ice sheet

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A NASA satellite photo shows Greenland’s ice sheet.

Fossil fuels leave clear fingerprint

By Summit Voice

FRISCO — Researchers find all sorts of climate clues in Greenland’s ice sheet, and now, a new study of isotopes shows a distinct fingerprint of the long-term increase in atmospheric acidity.

The research by University of Washington researchers shows a decrease in levels of the isotope nitrogen-15 in core samples from Greenland ice starting around the time of the Industrial Revolution.

The decrease has been attributed to a corresponding increase in nitrates associated with the burning of fossil fuels. But the new evaluation links the decline increased acidity in the atmosphere — primarily from sulfur dioxide, which in the atmosphere is transformed to sulfuric acid, according Lei Geng, a UW research associate in atmospheric sciences. Following the Industrial Revolution, sulfur dioxide emissions increased steadily because of coal burning. Continue reading

Global warming could lead to runaway ice cap meltdown

New study shows very fast response between global temperature and ice volume and sea level

“when significant ice-volume adjustments happen, they are rarely slow.”

By Summit Voice

FRISCO — A new study confirms the strong links between global temperatures, melting ice and sea level and suggests that sea level responds more quickly that previously believed, probably because of the feedback warming effect of open water.

Ice volume changes during ancient times can be reconstructed from sea-level records, but detailed assessments of the role of ice volume in climate change is hindered by inadequacies in sea-level records and/or their timescales.

Now, a research team led by Eelco Rohling, Professor of Ocean and Climate Change at the University of Southampton, has developed a new way to date sea level rise and accurately link it with changes in ice volume. The scientists were able to apply the new dating method throughout the entire last glacial cycle (150,000 years), which resulted in an unprecedented continuous sea-level record with excellent independent age control. Continue reading

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