Arctic Sea Ice : Forum

Cryosphere => Glaciers => Topic started by: abbottisgone on August 05, 2016, 04:28:07 PM

Title: Helheim and Fenris Glaciers
Post by: abbottisgone on August 05, 2016, 04:28:07 PM
http://glacierhub.org/2016/08/03/melting-glaciers-through-the-artists-lens/ (http://glacierhub.org/2016/08/03/melting-glaciers-through-the-artists-lens/)

 By looking at the link above and comparing two glaciers from their 1930s photos to more recent examples one should really not conclude too much, should they?

 Are these just poor photos for comparisons sake or am I simply not appreciating the loss shown in them?

 For instance, the Glacier on the left doesn't seem to have lost much at all- to be fair. The one on the right seems to have lost a visible amount but given the 80 year time difference in the photos then one could be forgiven for saying they really don't demonstrate much at all... to my mind atleast!

 Could I be wrong?

  :o
Title: Re: Helheim and Fenris Glaciers
Post by: budmantis on August 08, 2016, 06:15:09 AM
They looked pretty convincing to me Abbott. By the way, welcome back! Because you're from Australia I have to ask, are you "back in black"?
Title: Re: Helheim and Fenris Glaciers
Post by: binntho on August 11, 2016, 10:11:51 AM
For instance, the Glacier on the left doesn't seem to have lost much at all- to be fair. The one on the right seems to have lost a visible amount but given the 80 year time difference in the photos then one could be forgiven for saying they really don't demonstrate much at all... to my mind atleast!

Perhaps it doesn't look that much, but there are a few things to consider:

The images may be 80 years apart, but the retreat of the right-hand one (Helheim) didn't really start until 2001 (see http://www.climatehotmap.org/global-warming-locations/helheim-glacier-greenland.html (http://www.climatehotmap.org/global-warming-locations/helheim-glacier-greenland.html)). So we are talking about 11 years (2001 - 2012), not 80.

The left hand glacier shows some lowering and a small retreat on the left-most side, but given the quality of the images and the distance it is very hard to quantify.

Retreat of a glacier tongue is, I believe, mostly a response to less mass behind the tongue - not how fast the ice melts at the end of the tongue. The loss of mass in the ice tongue can be very clearly seen (I've put in a few lines that show how thick the glacier tongue was at it's maximum) and, again, this thinning of the tongue is really a much stronger indicator of lesser mass and lesser pressure in the ice sheet behind than of any melting taking place in the tongue itself.

However, as I understand it, a large part of the mass being lost in the ice sheet is lost through flowing out into ice tongues such as this one and breaking off at the end, one could say that the ice is draining out to sea, and the tongues are the drain pipes. Faster flow of ice in the glacier tongues happens as a result of melting, as warmer waters melt the tongue faster and increasing melt water flows from further upstream lubricate the tongue.

But faster flow does not cause retreat (although it might cause some thinning). Both the retreat and the thinning are direct indicators of loss of mass in the ice sheet itself, and as such are of much more significance than would appear at first.
Title: Re: Helheim and Fenris Glaciers
Post by: abbottisgone on August 22, 2016, 05:27:53 AM
They looked pretty convincing to me Abbott. By the way, welcome back! Because you're from Australia I have to ask, are you "back in black"?
What else would a "Night Prowler" wear?

 :-\  ;)
Title: Re: Helheim and Fenris Glaciers
Post by: abbottisgone on August 22, 2016, 05:37:40 AM
Wow, thanx binntho: those lines help a lot and I simply did not appreciate what I was looking at. There is a colour difference on the rock faces and I just didn't appreciate that.

Thank you both. I just came across this internet surfing and I thought I may aswell post it as a genuine attempt to try and understand what I at first considered a possible indicator of not much change at all.

I could have not posted it and dismissed it but thought I may aswell see what others with better understandings had to say, so cheers.
Title: Re: Helheim and Fenris Glaciers
Post by: budmantis on August 22, 2016, 09:04:12 AM
They looked pretty convincing to me Abbott. By the way, welcome back! Because you're from Australia I have to ask, are you "back in black"?
What else would a "Night Prowler" wear?

 :-\  ;)

And here I thought you were an ac/dc fan!
Title: Re: Helheim and Fenris Glaciers
Post by: abbottisgone on August 22, 2016, 09:06:10 AM
They looked pretty convincing to me Abbott. By the way, welcome back! Because you're from Australia I have to ask, are you "back in black"?
What else would a "Night Prowler" wear?

 :-\  ;)

And here I thought you were an ac/dc fan!

https://www.youtube.com/watch?v=I6TzeuxwO7A (https://www.youtube.com/watch?v=I6TzeuxwO7A)
Title: Re: Helheim and Fenris Glaciers
Post by: budmantis on August 22, 2016, 09:58:21 AM
You got me on that one! Never heard of Night Prowler.
Title: Re: Helheim and Fenris Glaciers
Post by: abbottisgone on September 13, 2016, 04:01:11 AM
I think  it might have been Bon Scots last song!??!
Title: Re: Helheim and Fenris Glaciers
Post by: budmantis on September 13, 2016, 02:42:47 PM
I think  it might have been Bon Scots last song!??!

R.I.P. Bon! You are missed.