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Some reading for the “anti-warmalists” and “climate-change deniers”

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Author Topic: Some reading for the “anti-warmalists” and “climate-change deniers”  (Read 36108 times)
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Kiwithrottlejockey
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« on: February 16, 2009, 04:45:24 pm »

Glacier to go in 20 years

NZPA | Thursday, 24 April 2008

MELTING ICE: The terminal lake of the Tasman Glacier complete with icebergs that have calved from the terminal face as viewed from a skiplane on Easter Monday, 24 March 2008.

MELTING ICE: The terminal lake of the Tasman Glacier complete with icebergs that have calved from the terminal face
as viewed from a skiplane on Easter Monday, 24 March 2008.


Climate change will see most of the Tasman Glacier in the Southern Alps melt away over the next 20 years, scientists say.

"In the past 10 years, the glacier has receded a hell of a lot," said glaciologist Martin Brook.

"It's just too warm for a glacier to be sustained at such a low altitude — 730 metres above sea level — so it melts rapidly and it is going to disappear altogether."

The Tasman Glacier is the biggest in the Southern Alps and, at 29 kilometres, was one of the longest in the world's temperate zones.

In 1973, there was no lake in front of the Tasman Glacier. New measurements taken last week indicate the lake at its foot is now 7km long, 2km wide and 245m deep.

The lake has attracted regular excursions by boatloads of tourists, but Dr Brook warned yesterday that they may be at risk from huge chunks of ice unexpectedly breaking loose underwater and surfacing as far as 60m from the glacier face.

"There's actually a sub-surface apron of ice that slopes away under the water for at least 50m or 60m from the front of the glacier," Dr Brook said. As this ice-apron melted, blocks of ice broke off and floated to the surface.

"This happens pretty quickly and is potentially a hazard for the tour boats that cruise up to the cliff: the blocks just pop out on the surface and some are between 5m and 10m in size."

The lake has been formed as the ice which makes up the glacier melts, and is a key factor in its destruction: the deeper the lake, the faster the retreat of the glacier.

According to another glaciologist, Trevor Chinn, the development of the lake was a tipping point: no amount of snow at the head of the glacier, the neve, can compensate for melting triggered by the lake.

The last major survey of the glacier was in the 1990s. Since then, the glacier has retreated 180m a year, exposing a basin carved out of rock more than 20,000 years ago when the glacier was a lot larger and more powerful.

http://www.stuff.co.nz/dominionpost/4494166a6479.html



Tasman Glacier could go in 20 years

Hot air blamed for Tasman Glacier's melt

By JOHN KEAST - The Press | Thursday, 24 April 2008

MELT DOWN: The Tasman Glacier is melting fast and will ultimately disappear, experts fear. DAVID HALLETT/The Press.

MELT DOWN: The Tasman Glacier is melting fast and will
ultimately disappear, experts fear.
— DAVID HALLETT/The Press


The Tasman Glacier in Mount Cook-Aoraki National Park is retreating at an alarming rate and will ultimately disappear, experts at Massey University warn.

Dr Martin Brook, lecturer in physical geography, said that in 1973 there was no lake in front of the glacier, but new measurements last week indicated the lake was now 7km long, 2km wide and 245m deep.

The lake is formed as ice in the glacier melts.

"In the last 10 years the glacier has retreated a hell of a lot. It's just too warm for a glacier to be sustained as such low altitude, 730 metres above sea level, so it melts rapidly and it is going to disappear altogether.

"Significantly, the deeper the lake, the faster the retreat of the glacier."

The lake could only grow to a length of 16km, which would mean a further 9km of glacier retreat.

"Using the empirical relationships between the water depth and glacier retreat rate, we could expect further retreat of between 477m and 822m each year. At these rates, it would take between 10 and 19 years for the lake to expand to its maximum," Brook said.

His work indicated that an extreme scenario for the future retreat of the glacier, developed by Dr Martin Kirkbride in the 1990s, was correct.

"The last major survey was in the 1990s and since then the glacier has retreated back 180m a year on average. This has exposed a huge rock basin which was eroded more than 20,000 years ago when the glacier was a lot larger and more powerful."

Research students are studying the glacier and lake using a new towfish sonar and echo-sounding equipment.

"The glacier followed a slow retreat phase for a while, in that a thermo-erosional notch in the ice cliff face would develop at the water line, melt back into the glacier undercutting the ice above, causing the ice to collapse into the lake.

"But what is happening now is that a short foot of ice is extending out into the lake away from the ice cliff, and the glacier is now in a period of fast retreat. This is because as the water depth increases, sodoes the speed of retreat — simply, a much larger part of the glacier is submerged and the water, even at only 2°C, is still able to melt the glacier ice," Brook said.

As well as looking at the Tasman Glacier, the team is analysing the newly exposed sub-surface landscape.

http://www.stuff.co.nz/thepress/4495365a24035.html

http://www.stuff.co.nz/4494061a7693.html



Tasman Glacier retreat extreme

Created: Wednesday, 23 April 2008 | Last updated: Thursday, 24 April 2008
Massey University News

From left: technician David Feek, senior lecturer Dr Ian Fuller and PhD student Claire Robertson looking at sub-bottom sediment using the towfish sonar. In the background is a high-precision GPS transmitter attached to the towfish, which gives its location to about 5mm accuracy.

From left: technician David Feek, senior lecturer Dr Ian Fuller and PhD student Claire Robertson
looking at sub-bottom sediment using the towfish sonar. In the background is a high-precision
GPS transmitter attached to the towfish, which gives its location to about 5mm accuracy.


PhD student John Appleby (left) and Honours student Rob Dykes (right) in a boat on the lake measuring depth with an echo sounder.

PhD student John Appleby (left) and Honours student Rob Dykes (right) in a boat on the lake
measuring depth with an echo sounder.


The Tasman Glacier is retreating faster than ever and will ultimately disappear, glaciologists are warning.

In 1973 there was no lake in front of the Tasman Glacier, says Dr Martin Brook, lecturer in physical geography in the School of People, Environment and Planning. New measurements taken last week indicate the lake, formed by ice melt from the glacier, is now 7km long, 2km wide and 245m deep. The lake has been formed as the ice which makes up the glacier melts.

“In the last 10 years the glacier has receded a hell of a lot,” Dr Brook says. “It’s just too warm for a glacier to be sustained at such a low altitude, 730m above sea level, so it melts rapidly and it is going to disappear altogether. Significantly, the deeper the lake, the faster the retreat of the glacier.”

Dr Brook says the lake can only grow to a length of about 16km, which would mean a further 9km of glacier retreat.

“Using the empirical relationships between water depth and glacier retreat rate we could expect further retreat of between 477m and 822m each year. At these rates it would take between 10 and 19 years for the lake to expand to its maximum.”

His work indicated that an extreme scenario for the future retreat of the Tasman Glacier, developed by Dr Martin Kirkbride in the 1990s, was correct.

“The last major survey was in the 1990s and since then the glacier has retreated back 180 metres a year on average. This has exposed a huge rock basin which was eroded more than 20,000 years ago when the glacier was a lot larger and more powerful.”

Dr Brook and a number of research students are studying the glacier and the lake using a new towfish sonar and echo sounding equipment to measure the depth and analyse sediments under the lake.

“The glacier followed a slow retreat phase for a while, in that a thermo-erosional notch in the ice cliff face would develop at the water line, melt back into the glacier undercutting the ice above, causing the ice to collapse into the lake.

“But what is happening now is that a short foot of ice is extending out into the lake away from the ice cliff, and the glacier is now in a period of fast retreat. This is because as the water depth increases so does the speed of retreat — simply, a much larger part of the glacier is submerged and the water, even at only two degrees celcius, is still able to melt the glacier ice.

“The result is large pieces of ice fracturing off the ice foot and floating on the surface — the debris on the icebergs on the surface of the lake and the icebergs are a reflection of this.”

As well as addressing the future of the Tasman Glacier, which is in Aoraki Mount Cook National Park, the team is analysing the newly exposed sub-surface landscape. The project is also interested in the glacier because it is very different to the clean-ice glaciers on the West Coast. Tasman is covered in rock and debris, and has a different relationship with climate, Dr Brook says, as well as different patterns of retreat.

“In particular, although there’s a near-vertical ice cliff at the front of the glacier that terminates in the lake, there’s actually a sub-surface apron of ice that slopes away under the water for at least 50m or 60m from the front of the glacier. As this ice-apron melts, blocks of ice break off and float to the surface. This happens pretty quickly and is potentially a hazard for the tour boats that cruise up to the cliff — the blocks just pop out on the surface and some are between 5m and 10m in size.”

http://www.massey.ac.nz/massey/about-us/news/article.cfm?mnarticle=tasman-glacier-retreat-extreme-23-04-2008
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