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Large chunks of ice break from Tasman Glacier in South Island
ANTHONY HARRIS/FACEBOOK
8
February,
2019
Photos
have emerged of huge chunks of ice which have broken off the Tasman
Glacier.
The
photos were posted to Facebook by two local guides who were alerted
to the event in the Aoraki/Mount Cook National Park early
on Wednesday morning.
"Glacier
Explorers called us about the event so we got there after they had
cleaned up some of the chaos," Anthony Harris, a guide at
Southern Alps Guiding, said.
Large
chunks of ice have come off the Tasman Glacier on the South Island's
west coast.
"Luckily
the kayaks were racked and above the height of the waterline."
A
tidal surge up to 2 metres high smashed the jetty about and lifted a
boat trailer upside down onto another trailer, Harris said.
The
process is known as glacial calving.
"All
in all, this is the most significant event I've seen in the last five
years on the Tasman.
"The
present SE [southeasterly] is holding these bergs in the northern
section of the lake and will do so for at least another day or two.
"Once
we get a NW [northwester] they will begin to fill the lake with bergs
of all sizes ... some of these are really big."
Glaciologist
Heather Purdie says large calving events happen about once every two
years at the Tasman Glacier.
The
breaking of ice chunks from the edge of glaciers is known as glacial
calving.
University
of Canterbury glaciologist Heather Purdie said large calving
events like this one happened about once every two years on the
Tasman Glacier.
They
were caused by glacial ice above the water melting, putting
pressure on the ice beneath it still under the water.
The
photos were taken by two guides who operate in the area.
When
the pressure became too much, the ice eventually snapped off.
"The
water gets in underneath the ice and sort of jacks it up, and it
snaps off.
"Large
calving events are less frequent but the icebergs that come up are
really big."
The
calving was caused by ice above the water melting, putting pressure
on ice still under the water.
The
calving was not necessarily the result of global warming, although
the glacier retreating and becoming smaller was attributable to
warming, Purdie said.
"Not necessarily because of global warming". Yeah, right!
This is from last year
NZ glaciers shrank significantly in hot summer
The summer heatwave has massively affected New Zealand's glaciers, resulting in the largest annual ice loss on record.
10
May, 2018
The
meltback was observed by the annual Glacier Snowline Survey, a
collaboration between NIWA and Victoria University.
Survey
founder Trevor Chinn said it was one of the largest glacier meltbacks
since he began the survey in 1977.
"A
glacier is the best climate change indicator you can use," he
said.
New
Zealand glaciers have lost 30 percent of their ice, in the 40 years
that the annual snowline survey has been running.
Whether
these dramatic results could be directly attributed to climate change
"is the $64,000 question", Niwa climate scientist Andrew
Lorrey said.
Niwa
said it was embarking on formal testing in collaboration with
Victoria University and the University of Melbourne to see if a
definitive correlation could be found.
"Can
you actually get a natural event like this, or is it something where
climate change has loaded the dice and it's pushed us over some sort
of threshold?" Dr Lorrey said.
"Those
are the questions we're looking to answer."
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