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Neven

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Himalayan glaciers
« on: November 26, 2015, 04:29:37 PM »
There wasn't a topic yet for this specific subject (I think), and this work that has just been published might be a good topic opener:

Revealing glacier flow and surge dynamics from animated satellite image sequences: examples from the Karakoram

F. Paul
Department of Geography, University of Zurich, Zurich, Switzerland

Abstract. Although animated images are very popular on the internet, they have so far found only limited use for glaciological applications. With long time series of satellite images becoming increasingly available and glaciers being well recognized for their rapid changes and variable flow dynamics, animated sequences of multiple satellite images reveal glacier dynamics in a time-lapse mode, making the otherwise slow changes of glacier movement visible and understandable to the wider public. For this study, animated image sequences were created for four regions in the central Karakoram mountain range over a 25-year time period (1990–2015) from freely available image quick-looks of orthorectified Landsat scenes. The animations play automatically in a web browser and reveal highly complex patterns of glacier flow and surge dynamics that are difficult to obtain by other methods. In contrast to other regions, surging glaciers in the Karakoram are often small (10 km2 or less), steep, debris-free, and advance for several years to decades at relatively low annual rates (about 100 m a−1). These characteristics overlap with those of non-surge-type glaciers, making a clear identification difficult. However, as in other regions, the surging glaciers in the central Karakoram also show sudden increases of flow velocity and mass waves travelling down glacier. The surges of individual glaciers are generally out of phase, indicating a limited climatic control on their dynamics. On the other hand, nearly all other glaciers in the region are either stable or slightly advancing, indicating balanced or even positive mass budgets over the past few decades.


The Cryosphere

And EGU press release here (where the animations can be viewed)
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budmantis

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Re: Himalayan glaciers
« Reply #1 on: August 24, 2016, 07:04:40 AM »
Neven: I know this goes back almost a year but I found the information you posted here to be quite interesting. It seems the Karakorum range glaciers are keeping close to equilibrium, with no significant loss of mass balance. The time lapse of the Baltoro glacier was great.

Espen

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Re: Himalayan glaciers
« Reply #2 on: September 01, 2016, 07:16:58 PM »
Animated glacier images, that must be a something really new ? ;)
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budmantis

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Re: Himalayan glaciers
« Reply #3 on: September 01, 2016, 07:44:51 PM »
Animated glacier images, that must be a something really new ? ;)

Quite! Still in the development stage, I guess.

skanky

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Re: Himalayan glaciers
« Reply #4 on: September 07, 2016, 10:26:54 AM »
On July 17, 2016, a huge stream of ice and rock tumbled down a narrow valley in the Aru Range of Tibet. When the ice stopped moving, it had spread a 30-meter-thick pile of debris across 10 square kilometers. Nine people, 350 sheep, and 110 yaks in the remote village of Dungru were killed during the avalanche.
The massive debris field makes this one of the largest ice avalanches ever recorded. The only event of a comparable size was a 2002 avalanche from Kolka Glacier in in the Caucasus , explained Andreas Kääb, a glaciologist at the University of Oslo.
A multispectral imager on the European Space Agency’s Sentinel-2 satellite captured an image of the debris field on July 21, 2016. The Operational Land Imager, a similar instrument on Landsat 8, acquired an image on June 24, 2016, that shows the same area before the avalanche.
The cause of the avalanche is unclear. “This is new territory scientifically,” said Kääb. “It is unknown why an entire glacier tongue would shear off like this. We would not have thought this was even possible before Kolka happened.”


http://earthobservatory.nasa.gov/IOTD/view.php?id=88677&eocn=home&eoci=iotd_readmore

budmantis

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Re: Himalayan glaciers
« Reply #5 on: September 08, 2016, 06:34:18 AM »
Skanky, great post! I think the Aru mountains are in the northern part of the Tibetan plateau. That glacier must have lost more than half its mass in the avalanche.

RoxTheGeologist

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Re: Himalayan glaciers
« Reply #6 on: September 08, 2016, 08:19:49 PM »
Skanky, great post! I think the Aru mountains are in the northern part of the Tibetan plateau. That glacier must have lost more than half its mass in the avalanche.

What's worrying for me is that this mechanism might apply to much larger glaciers, such as those comprising the Greenland ice sheet. That would create a rather sudden change in sea level, probably with a decent sized tidal wave.

budmantis

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Re: Himalayan glaciers
« Reply #7 on: September 10, 2016, 04:07:44 PM »
Skanky, great post! I think the Aru mountains are in the northern part of the Tibetan plateau. That glacier must have lost more than half its mass in the avalanche.

What's worrying for me is that this mechanism might apply to much larger glaciers, such as those comprising the Greenland ice sheet. That would create a rather sudden change in sea level, probably with a decent sized tidal wave.

Rox, check out this link. On a limited scale it does address your question.

https://weather.com/science/environment/news/greenland-glacier-zachariae-isstrom-melting

solartim27

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Re: Himalayan glaciers
« Reply #8 on: October 27, 2016, 09:51:56 PM »
Second landslide next to the first one from above.  Pictures in other post, or click the link:
http://earthsky.org/earth/2nd-massive-ice-avalanche-in-tibet
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johnm33

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Re: Himalayan glaciers
« Reply #9 on: October 28, 2016, 11:35:34 AM »
It took a while after skankys post for me to make the connection, but some while ago I read an article about how in the Alps[Swiss] the north face of some mountains which had been assumed to be solid rock were actually being held together by long frozen ice. As the ice thawed whole rock faces collapsed, is that what we're seeing here?
« Last Edit: October 29, 2016, 12:00:42 PM by johnm33 »

skanky

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Re: Himalayan glaciers
« Reply #10 on: October 28, 2016, 10:58:26 PM »
« Last Edit: October 31, 2016, 11:21:23 PM by skanky »

budmantis

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Re: Himalayan glaciers
« Reply #11 on: October 31, 2016, 05:59:21 AM »
http://www.bbc.com/news/world-asia-37797559

"Nepal drains dangerous Everest lake".

"Nepal army says it has finished draining a dangerous glacial lake near Mt. Everest to a safe level".

oren

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Re: Himalayan glaciers
« Reply #12 on: October 31, 2016, 10:40:32 AM »
http://www.bbc.com/news/world-asia-37797559

"Nepal drains dangerous Everest lake".

"Nepal army says it has finished draining a dangerous glacial lake near Mt. Everest to a safe level".

Interesting. The scale of the problem is huge: Imja is one of thousands of glacial lakes in the Himalayas. Work on building the outlet took six months under tough conditions, and water release took 2 more months. They now plan to replicate the process to other glacial lakes. I am guessing budget constraints will prevent a complete fix to all lakes at risk, as happens in most places (levees, seawalls, etc.).

Archimid

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Re: Himalayan glaciers
« Reply #13 on: October 31, 2016, 05:17:40 PM »
Noah's ark, Gilgamesh's epic, the lost city of Atlantis, they could have been victims of glacial lake melt at the beginning of the Holocene. It the arctic did become ice free, it would have warmed the planet very fast, which would have melt the enormous glaciers in the northern hemisphere and cause flooding much worse that we see this year. I wonder how the world population was affected during those events.
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oren

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Re: Himalayan glaciers
« Reply #14 on: October 31, 2016, 08:00:08 PM »
Noah's ark, Gilgamesh's epic, the lost city of Atlantis, they could have been victims of glacial lake melt at the beginning of the Holocene. It the arctic did become ice free, it would have warmed the planet very fast, which would have melt the enormous glaciers in the northern hemisphere and cause flooding much worse that we see this year. I wonder how the world population was affected during those events.

Atlantis is not considered a historical account. Noah's ark (like many biblical tales) is derived from other near east flood myths, possibly with a bit of history in them but not necessarily. If these myths are historical, they may derive from the flooding of both the Persian Gulf (and the southern end of Mesopotamian settlements) and the Black Sea (and the northern end of Anatolian settlements) around 6000 BC. A glacial melt lake is most probably not the reason for these myths.

Archimid

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Re: Himalayan glaciers
« Reply #15 on: November 01, 2016, 12:17:59 AM »
The way I look at it, there have been many lost cities of Atlantis, many Noahs and many Gilgamesh over time. I'm pretty sure that as the world warmed at the beginning of the Holocene and the last remaining glaciers disappeared, many human coastal settlements were lost, some of them relatively advanced for their time.  It can happen very fast. For example, if the arctic sea ice did disappear at the beginning of the Holocene, then temperatures would have shot up quite a bit melting glaciers at a much faster rate than today. I Imagine that water vapor would have increased too. That could have caused great floods that no human alive has ever seen. Also a high tide after a year with particularly fast glacier melt, could completely submerge vulnerable ancient coastal civilizations.

These events stayed on the collective memory of humanity in the form of Atlantis, Noah and Gilgamesh. I don't think we will see these events at the scale of early Holocene simply because there is much less ice today that there was then.
I am an energy reservoir seemingly intent on lowering entropy for self preservation.

budmantis

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Re: Himalayan glaciers
« Reply #16 on: November 01, 2016, 03:07:42 AM »
You're probably right Archimid, although the collapse of the West Antarctic Ice Sheet would raise sea levels significantly.

skanky

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Re: Himalayan glaciers
« Reply #17 on: December 14, 2016, 11:00:20 AM »
Using declassified spy satellite images to determine longer term glacier changes: http://www.bbc.co.uk/news/science-environment-38307176