Nav: Home

Investigating glaciers in depth

October 24, 2018

Global sea level is rising constantly. One factor contributing to this rise is the melting of the glaciers. However, although the surface area of the glaciers has been well mapped, there is often no information regarding their thickness, making it impossible to calculate their volume. As a result, we cannot accurately calculate the effects on sea levels. Dr. Johannes Fürst from the Institute of Geography at Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) has developed an approach which can be used to draw up regional ice thickness maps for glaciers. He has now produced such a map for Svalbard and published his findings in Geophysical Research Letters (DOI: 10.1029/2018GL079734).

New ice thickness map, new findings

The FAU geographer Johannes Fürst has gathered and evaluated data measured by a number of international research teams since the early 1980s. These measurements have been entered into the new map of glacier thickness on Svalbard, an archipelago to the north of Norway with the main island Spitsbergen. Whereas previous studies have only looked at individual thickness measurements in isolation, projecting the total ice volume evolution on the basis of the surface area and just a few measurements, this map takes all available measurements into account in order to obtain a reliable estimate of the total ice volume. At 6,200 cubic kilometres, it is approximately one third smaller than previously presumed. Nevertheless, if this ice were to melt all of a sudden, it would still cause global sea levels to rise by 1.5 centimetres.

Fürst also provides an associated map of error estimates. Errors may be a direct result of the thickness measurements. At these locations, errors can readily be calculated. It is more difficult for positions away from the measurements. Starting from a certain measurement point, errors are estimated along flowline down the glacier based on speed, direction as well as local mass gain and loss. Researchers could also use this formula to calculate the ice thickness uncertainty for regions where hardly any measurements have been taken.

'In order to calculate the future demise of glaciers accurately, we have to know the thickness of the glaciers. Until now, however, we have only had very rough estimates, which vary greatly. This is down to the lack of measurements taken worldwide. My approach, which can also be used for other glaciers, may help in this respect,' Johannes Fürst explains.

Data, data, data

There are nearly 1,700 glaciers on Svalbard. On these, one million point measurements of the ice thickness have already been collected, ranging in date from the 1980s to the present day. These measurements have mainly been provided by British, Spanish, Norwegian and Danish teams of researchers, but Polish, Icelandic, French and Japanese researchers have also collected valuable data. One method of determining the thickness of the ice cap is using radar. A radar signal is sent down through the ice. The longer the signal takes to return to the measuring device, the thicker the ice is. 'It's like ping-pong: the table tennis player hits the ball and waits until it comes back. The longer he has to wait, the further away the ball was,' explains Fürst. Another method involves making several boreholes through several hundred metres of ice. The extracted ice cores were used, for example, to study past fluctuations in temperature or precipitation. A mining company has also used drilling in order to better judge the risks of mining for coal underneath the glacier. Fürst has included all these measurements in the ice thickness map.

Going with the flow

The ice thickness map gives new insights into the dynamic ice loss of glaciers. When new snow falls, its weight compresses previous layers of snow and a new mass of ice is gradually formed. This ice then flows downglacier, in some places until it reaches the ocean. Huge icebergs regularly break off from the ice cliffs there. The mass lost there every year can only be estimated accurately if you know how thick the ice at the ice cliffs actually is. Johannes Fürst has calculated an average thickness of 135 metres for all marine-terminating glaciers in the Svalbard archipelago. The previous estimate was 214 metres. Thanks to the new map, we are now able to accurately estimate the dynamic ice loss from Svalbard glaciers.
-end-


University of Erlangen-Nuremberg

Related Glaciers Articles:

Drones help map Iceland's disappearing glaciers
Dr. Kieran Baxter from the University of Dundee has created composite images that compare views from 1980s aerial surveys to modern-day photos captured with the help of state-of-the-art technology.
Disappearing Peruvian glaciers
It is common knowledge that glaciers are melting in most areas across the globe.
New insight into glaciers regulating global silicon cycling
A new review of silicon cycling in glacial environments, led by scientists from the University of Bristol, highlights the potential importance of glaciers in exporting silicon to downstream ecosystems.
Tidewater glaciers: Melting underwater far faster than previously estimated?
A tidewater glacier in Alaska is melting underwater at rates upwards of two orders of magnitude greater than what is currently estimated, sonar surveys reveal.
Asia's glaciers provide buffer against drought
A new study to assess the contribution that Asia's high mountain glaciers make to relieving water stress in the region is published this week (May 29, 2019) in the journal Nature.
Melting small glaciers could add 10 inches to sea levels
A new review of glacier research data paints a picture of a future planet with a lot less ice and a lot more water.
Using satellites to measure rates of ice mass loss in glaciers
Researchers from Friedrich-Alexander-Universität Erlangen-Nürnberg have now investigated all glacial areas in South America in more detail than ever before, from the tropical areas to the subpolar regions.
Volcanoes and glaciers combine as powerful methane producers
Large amounts of the potent greenhouse gas methane are being released from an Icelandic glacier, scientists have discovered.
How much debris is lying on glaciers?
A study by scientist Dirk Scherler of the German Research Centre for Geosciences GFZ and two colleagues from Switzerland shows a possibility to detect the extent of debris on mountain glaciers globally and automatically via satellite monitoring.
Investigating glaciers in depth
Global sea level is rising constantly. One factor contributing to this rise is the melting of the glaciers.
More Glaciers News and Glaciers Current Events

Top Science Podcasts

We have hand picked the top science podcasts of 2019.
Now Playing: TED Radio Hour

Risk
Why do we revere risk-takers, even when their actions terrify us? Why are some better at taking risks than others? This hour, TED speakers explore the alluring, dangerous, and calculated sides of risk. Guests include professional rock climber Alex Honnold, economist Mariana Mazzucato, psychology researcher Kashfia Rahman, structural engineer and bridge designer Ian Firth, and risk intelligence expert Dylan Evans.
Now Playing: Science for the People

#540 Specialize? Or Generalize?
Ever been called a "jack of all trades, master of none"? The world loves to elevate specialists, people who drill deep into a single topic. Those people are great. But there's a place for generalists too, argues David Epstein. Jacks of all trades are often more successful than specialists. And he's got science to back it up. We talk with Epstein about his latest book, "Range: Why Generalists Triumph in a Specialized World".
Now Playing: Radiolab

Dolly Parton's America: Neon Moss
Today on Radiolab, we're bringing you the fourth episode of Jad's special series, Dolly Parton's America. In this episode, Jad goes back up the mountain to visit Dolly's actual Tennessee mountain home, where she tells stories about her first trips out of the holler. Back on the mountaintop, standing under the rain by the Little Pigeon River, the trip triggers memories of Jad's first visit to his father's childhood home, and opens the gateway to dizzying stories of music and migration. Support Radiolab today at Radiolab.org/donate.