Dynamic Planet B/C Question Marathon

[PacificGoldenPlover]

Just putting it out there, surges do NOT occur due to sudden accumulation. It would require a ridiculously large amount of snow dropped over a huge surface area. Surges happen due to greatly enhanced basal slip, and relative to the glacier thickness, there really is no situation where basal water pressure could be that much affected simply by accumulation.

In addition, mass accumulation does not explain why the vast majority of surges are cyclical.

[Crazy Puny Man]

Not even through avalanches or landslides? Sure, not too much cyclical, but not even possible?

They also occur due to bedrock failure/sudden slippage...which, to my understanding, is caused by an accumulation of stress in the glacier which can can result from slow-moving ice at the terminus 'damming' up faster-moving ice up-glacier, and the glacier surges once the stress goes beyond a certain 'critical point.'

Could that also (somewhat) explain the cyclical nature of surges too? In certain cases?

EDIT: what is your source(s) for this information? and in general too, if you wouldn't mind sharing xD

[PacificGoldenPlover]

Not even through avalanches or landslides? Sure, not too much cyclical, but not even possible?

They also occur due to bedrock failure/sudden slippage...which, to my understanding, is caused by an accumulation of stress in the glacier which can can result from slow-moving ice at the terminus 'damming' up faster-moving ice up-glacier, and the glacier surges once the stress goes beyond a certain 'critical point.'

Could that also (somewhat) explain the cyclical nature of surges too? In certain cases?

EDIT: what is your source(s) for this information? and in general too, if you wouldn't mind sharing xD

Well, for instance, glaciers are fairly picky as to whether or not they will surge. If a glacier is a nonsurging glacier, then it will almost certainly not surge even if a lot of snow is placed on top of it.

Glaciers surge because stress causes a positive feedback cycle where channels in the ice collapse, forcing the meltwater to travel to the base of the glacier, essentially lifting the glacier up. So, if immediately a after a surge an avalanche fell on a glacier, the glacier would not surge because it needs time for these channels to reform.

It's kind of a chicken-and-egg question. I see where you are coming from, but I still say location, history, and the state of englacial meltwater are all much better determiners for whether or not a glacier will surge.

[Crazy Puny Man]

Not even through avalanches or landslides? Sure, not too much cyclical, but not even possible?

They also occur due to bedrock failure/sudden slippage...which, to my understanding, is caused by an accumulation of stress in the glacier which can can result from slow-moving ice at the terminus 'damming' up faster-moving ice up-glacier, and the glacier surges once the stress goes beyond a certain 'critical point.'

Could that also (somewhat) explain the cyclical nature of surges too? In certain cases?

EDIT: what is your source(s) for this information? and in general too, if you wouldn't mind sharing xD

Well, for instance, glaciers are fairly picky as to whether or not they will surge. If a glacier is a nonsurging glacier, then it will almost certainly not surge even if a lot of snow is placed on top of it.

Glaciers surge because stress causes a positive feedback cycle where channels in the ice collapse, forcing the meltwater to travel to the base of the glacier, essentially lifting the glacier up. So, if immediately a after a surge an avalanche fell on a glacier, the glacier would not surge because it needs time for these channels to reform.

It's kind of a chicken-and-egg question. I see where you are coming from, but I still say location, history, and the state of englacial meltwater are all much better determiners for whether or not a glacier will surge.

Um...I'm not sure I follow you >_> The channels are in the middle of the glacier, i.e. not at the base, right? Also, wouldn't the meltwater travel to the base through moulins? Moulins are how supraglacial meltwater gets down to the base...

Are you saying that the meltwater, instead of traveling through tunnels in the ice, percolate/leak through the glacier and travel to the base? Or that the added stress simply increases pressure & therefore lowers the ice's melting point?

[PacificGoldenPlover]

I will respond on the regular dp thread.

EDIT: Since it has been a while since anyone has posted any questions, I'll post one:

What is the largest nonpolar, non icecap glacier in the world? Which countries is it located in? What is its geopolitical importance, and how is this importance accelerating its retreat?

[BYHscioly]

It's the Siachen glacier, located somewhere in the Kashmir region (India/Pakistan/China). It's important since it's one of the sites of territorial conflict between India and Pakistan, and the conflict - the heat and stuff generated from the military operations - sped up its retreat to 110 meters a year as of now.

What are D-O events, how are they caused, what are they like, and how do they effect the cryosphere?

[PacificGoldenPlover]

Not sure I know the answer to all the parts. Here goes:

D-O stands for Dansgaard-Oeschger event. It is the phenomenon where global temperatures rapidly warm following a glacial period. I would assume they are a byproduct of the Milankovitch Cycle, but not positive what specifically about them causes it. As said before, they lead to massive warming, thus rapid retreat of glaciers, ice sheets after a glacial maximum.

Belated affirmative to my previous question.

[Crazy Puny Man]

Plover, I think that's your cue to post the next question...you got the last one right, after all

[PacificGoldenPlover]

Whatever, here goes.
the first ice core ever drilled to the bottom of an ice sheet was located where?

[Crazy Puny Man]

God dammit! Why can I never answer your questions