Alaska glaciers make large contributions to global sea level rise

Alaska glaciers make large contributions to global sea level rise
Paul Claus with Operation IceBridge Alaska flies a lidar survey over the crevassed Tana Glacier in Southcentral Alaska. A new study finds Alaska's melting glaciers are adding enough water to the Earth's oceans to cover the state of Alaska with a 1-foot thick layer of water every seven years. Credit: Chris Larsen

Alaska's melting glaciers are adding enough water to the Earth's oceans to cover the state of Alaska with a 1-foot thick layer of water every seven years, a new study shows.

The study found that climate-related melting is the primary control on mountain glacier loss. Glacier loss from Alaska is unlikely to slow down, and this will be a major driver of global in the coming decades, according to the study's authors.

"The Alaska region has long been considered a primary player in the global sea level budget, but the exact details on the drivers and mechanisms of Alaska glacier change have been stubbornly elusive," said Chris Larsen, a research associate professor with the Geophysical Institute at the University of Alaska Fairbanks. Larsen is lead author of the new study accepted for publication in Geophysical Research Letters, a journal of the American Geophysical Union.

The UAF and U.S. Geological Survey research team analyzed surveys of 116 glaciers in the Alaska region across 19 years to estimate ice loss from melting and . The team collected airborne lidar altimetry data as part of NASA's Operation IceBridge and integrated the new data with information from the 1990s collected by UAF scientist and pilot Keith Echelmeyer.

They combined the lidar observations with a new mountain glacier inventory that characterizes the size and shape of every glacier in the Alaska region, which includes the glaciers of Alaska, southwest Yukon Territory and coastal northern British Columbia.

Alaska glaciers make large contributions to global sea level rise
Estimated mass balance (1994-2013) for surveyed and unsurveyed glaciers in the most densely glacierized subregion of Alaska. The inset shows the entire region. Black lines indicate survey flight lines. Credit: Chris Larsen

"This large dataset of direct observations enabled a much more detailed assessment and attribution of recent glacier change than previously possible," Larsen said.

Mountain glaciers hold less than 1 percent of the Earth's glacial ice volume. The rest is held in ice sheets on Antarctica and Greenland. However, the rapid shrinking of causes nearly one-third of current , previous research has shown.

"Alaska has been identified for years as a big contributor in global sea level rise, but until now we have not had a clear understanding of the processes responsible for the rapid changes of these glaciers," said Shad O'Neel, a co-author of the new paper and geophysicist with the USGS Alaska Science Center in Anchorage.

The study used the airborne observations to compare the changes of two main types of glaciers: those that end on the land, and those that end in lakes or the ocean, referred to as calving glaciers. Any glacier can lose mass through surface melting, but only those ending in water can lose ice through iceberg calving.

"We've long wondered what the contribution of iceberg calving could be across the entire state," O'Neel said. He noted that Columbia Glacier in Prince William Sound has retreated more than 19 kilometers (12 miles) mostly because of iceberg calving and thinned by more than 450 vertical meters (1,500 vertical feet) since 1980.

Using the newly enabled ability to separate glaciers into different categories using the lidar data, the researchers made some surprising discoveries.

"Our results show the regional contribution of to sea level rise to be almost negligible," Larsen said. Tidewater glaciers are glaciers that end in the ocean. "Instead, we show that glaciers ending on land are losing mass exceptionally fast, overshadowing mass changes due to iceberg calving, and making climate-related melting the primary control on mountain glacier mass loss."

"This work has important implications for global projections. With improved understanding of the processes responsible for Alaska glacier changes, models of the future response of these to climate can be improved," Larsen said.

"Thinking about the future, it means that rates of loss from Alaska are unlikely to decline, since surface melt is the predominant driver, and summer temperatures are expected to continue to increase. There is a lot of momentum in the system, and Alaska will continue to be a major driver of change in upcoming decades," he added.


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Melting glaciers have big carbon impact, study shows

More information: Geophysical Research Letters, onlinelibrary.wiley.com/doi/10 … ytk-41855.5282060185
Journal information: Geophysical Research Letters

Citation: Alaska glaciers make large contributions to global sea level rise (2015, June 17) retrieved 25 August 2019 from https://phys.org/news/2015-06-alaska-glaciers-large-contributions-global.html
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Jun 17, 2015
Greenland is the real worry, with Antarctica.

Say goodbye to Manhattan.

Jun 17, 2015
Doesn't it surprise anyone else that these glaciers, found specifically in the USA, have unexpectedly large contributions to sea level rise? It sounds a little suspicious to me, especially the close proximity of Dr. Larsen to the site of the study. Who is to say he isn't skewing the study towards significant results by his own actions? He could be going out late at night and falsifying the data. For instance he could be skiing excessively in sites off-limits to the general public, or pumping Fairbanks municipal water right underneath the glacier. Who would ever know?

Jun 17, 2015
Perhaps the particulates from Asian industrialization is causing a dirty snow effect. Tropical fossils can be found in the rocks as I recall, so we know warming has occurred in this region previously. According to the 'Panama Hypothesis', more Arctic fresh water led to greater glaciation eventually...as I recall.

Jun 18, 2015
1.7 of an inch over Alaska every year adds how much height to the oceans? Is this significant enough to warrant a story? Or is it just more alarmist FUD.

Jun 18, 2015
Doesn't it surprise anyone else that these glaciers, found specifically in the USA, have unexpectedly large contributions to sea level rise? It sounds a little suspicious to me, especially the close proximity of Dr. Larsen to the site of the study. Who is to say he isn't skewing the study towards significant results by his own actions? ...?


Is that... satire?

1.7 of an inch over Alaska every year adds how much height to the oceans? Is this significant enough to warrant a story? Or is it just more alarmist FUD.


"Current" sea level rise. The greatest contributor to sea level rise long-term will be Antarctic melt because it's land ice. They're talking about the current sea level rise of approximately 20cm and the article itself answers you question - "nearly one-third".

Jun 18, 2015
1.7 of an inch over Alaska every year adds how much height to the oceans? Is this significant enough to warrant a story? Or is it just more alarmist FUD.


It comes out to .88 in/century. Should I worry yet? I understand that Alaska is a small part of a larger whole but I don't get reporting on just one small part of that whole.

Jun 18, 2015
5 metres of sea level rise is already locked in and another 60 metres on the way.

I would like to see a map with the projected new shore lines.

Prestige coastal real estate will become swamp land.

Flood plains will become unfarmable.

Statue of Liberty poking out of the sandy beach - Planet of the Humans.

Jun 18, 2015
Nobody actually believes that, because if they did believe that there would be absolute outrage and protests in front of every government building 24/7.

Jun 18, 2015
Marko is correct. The Great Central Valley is in danger of returning to a salt water lake or estuary.

Learn to grow your own avocados.

Jun 18, 2015
In 2005, the United Nations Environment Programme (UNEP) warned that imminent sea-level rises, increased hurricanes, and desertification caused by "man-made global warming" would lead to massive population disruptions.

The 2005 UNEP predictions claimed that, by 2010, some 50 million "climate refugees" would be frantically fleeing from those regions of the globe. The areas in question failed to produce a single "climate refugee".

In 2007, 2008, and 2009, Al Gore, publicly warned that the North Pole would be "ice-free" in the summer by around 2013.

The Earth's climate has always changed, and very likely will continue to change, regardless of what humans do. What is now clear, is that the establishment has no idea what those changes will be; much less what drives the changes or how to control them.

Think the $360 billion-per-year climate establishment cares? Think again.


Jun 18, 2015
Nobody actually believes that, because if they did believe that there would be absolute outrage and protests in front of every government building 24/7.


You mean like the 20k protesting just this week in England? Or the more 100k that have turned out three times in Australia in the last year? Or the more than 100k that protested in the states last year? Or last year's 2500 coordinated worldwide protests? You mean like those?

Jun 18, 2015
Its not funny. I have been on the tracks of an Inuit climate change syndicate for many years now. They cover it up as oil prospecting. The amount of explosives and industrial vehicles they are bringing into the polar region is enough for a small war . They teach even their little children to defecate on the whitest snow. For them every little bit counts. That is the worst part: for a new generation of eskimo children, the ends justifies the means.

But who can blame them? The snow is often the only thing they are born with. Every millimeter rise of ocean water brings them that much closer to owning their own penguin or snow mobile. They saw the wealth of nations, launching satellites and constructing massive ships for breaking the ice, and they organized. They started doing it their way. And now, pretty soon, the climate scientists will be completely finished with their own game, pinched out by ruthless efficiency, devotion and the often barely legal inuit labor practices.


Jun 19, 2015
I peed on the snow once and an entire continent was washed away...

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