Planes shoot lasers to measure Swiss glacial melt

A new project launched on Thursday provides more holistic conclusions about changes in the thickness of an entire glacier or group of glaciers. “The first results are promising,” said project leader Michael Zemp in a phone interview.

Glaciers are by definition constantly on the move; so slowly that the traditional measurement methods using wooden poles and snow-shovels seemed to suffice. But cheap and old techniques have only assessed a small number of areas in the Alps. Airborne laser technology could help reach all 2000 Swiss glaciers, according to Zemp.

Project 'Laser Scanning Experiment Oberwallis' is being carried out jointly by the glaciology and remote sensing units of the University of Zurich's geographical department. Research flights are carried out in collaboration with BSF Swissphoto, using an Optech ALTM 3100 laser scanning system.

The first flight took place four years ago over the Findell glacier close to Zermatt, beaming lasers as high as 4,000 metres. Scientists compared its findings with a second flight in October 2009. The comparison enables observers to assess differences in the volume and thickness in the ice over the four year period.

“In the past people did think that it’s pretty expensive,” said Zemp. The most recent Findell flight cost about 20,000 francs in aircraft and technology expenses, as well as the cost of a small team of university staff.

Philip Jörg, a PhD candidate involved in this project, explained in a press release published by the university on Thursday, how it works: “a strongly-bundled beam of light is shot from an aircraft and the time is measured that the light needs to reach the surface of the ice and bounce back to the aircraft.

From this so-called ‘run time’, the distance from the plane to the glacier can be precisely determined to within just a few centimetres.” The laser data and the exact location and position of the aircraft give rise to a highly precise, three-dimensional picture of the glacier's surface.

The scientists discovered that during the past four years the Findel Glacier has lost almost 3.5 metres of average ice thickness, and as much as 25 to 30 metres at its tongue. Overall, the glacier has lost around 49 million cubic metres of ice.

Zemp illustrates this with a staggering comparison: if the same volume of ice were melted and emptied into the Lake of Zurich, the water level of the lake would rise by about half a metre.

Part of the funding comes from Swiss energy company Axpo, which conducts a series of activities to demonstrate a sense of environmental responsibility. But for electricity generators, climate change is a commercial threat, as well as a social responsibility issue.

Zempf says his fly-bys will provide “practical information for hydrological operations,” which could help electricity generators understand the decline of hydro power associated with climate change.

Widmer Florian, spokesperson for another Swiss utility, Alpiq, told Swisster “the laser method developed by the University of Zurich seems interesting, but only to understand changes in volume.” There are other emerging technologies to compliment the traditional pole and shovel methods.

Alpiq supports an alternative project based on the Aletsch Glacier in collaboration with the Zurich Technical Institute (ETHZ), which uses heliborne georadar to measure the thickness of the glacier and deduces the available stock of water for hydro power generation.

But Zemp is optimistic that his laser technique will be used to help a variety of organisations to understand glacial activity: “this is also interesting for those in tourism and industry or for information on natural hazards,” he added.

The next flight on Zemp’s project will take place in the spring of 2010 when scientists will study the distribution of winter snow in the same area and a further flight is scheduled for the following autumn. The project is set to continue until 2012.