139 replies to this topic

[Gray-Wolf]

NDS, Hi!

Are you not misconstruing the article? I took it to mean that the 'freshening' of the surface layer meant it would freeze at higher temps therefore expanding the 'zone of freezing' and allowing earlier freezing of the surface in other areas? As we see with 'melt water pools' on sea ice freezing well before the surrounding 'salty' waters?

If the increased precipitation from the Peninsula extends out into Weddell we could expect to see earlier re-freeze there and an extension of that ice zone into the southern oceans ( thus expanding the 'extent' of ice cover?) The peninsula 'juts out' into the southern ocean and throws the circumpolar currents further out into the southern ocean (and makes some interesting patterns in the waters once the ice melts back with whirls and eddies in that frothy/floury water that remains post melt?)

There is also another type of ice consisting of brine filled snow that becomes frozen into a porous sea ice. This too would appear on extent charts but does not have the qualities of ice proper. Come the full onset of melt do not be surprised to see the peripheral pack in front of Weddell/Ross vanish at a rate of knots.

Talking of melt we have that large berg (from the rammed off Glacial tongue?) to keep an eye on this southern summer though ,so far,fears of it's interference in 're-freeze' appear to have been unfounded?

Edited by Gray-Wolf, 12 October 2010 - 13:28 .

[BornFromTheVoid]

Gray-Wolf, on 12 October 2010 - 13:27 , said:

NDS, Hi!

Are you not misconstruing the article? I took it to mean that the 'freshening' of the surface layer meant it would freeze at higher temps therefore expanding the 'zone of freezing' and allowing earlier freezing of the surface in other areas? As we see with 'melt water pools' on sea ice freezing well before the surrounding 'salty' waters?

If the increased precipitation from the Peninsula extends out into Weddell we could expect to see earlier re-freeze there and an extension of that ice zone into the southern oceans ( thus expanding the 'extent' of ice cover?) The peninsula 'juts out' into the southern ocean and throws the circumpolar currents further out into the southern ocean (and makes some interesting patterns in the waters once the ice melts back with whirls and eddies in that frothy/floury water that remains post melt?)

There is also another type of ice consisting of brine filled snow that becomes frozen into a porous sea ice. This too would appear on extent charts but does not have the qualities of ice proper. Come the full onset of melt do not be surprised to see the peripheral pack in front of Weddell/Ross vanish at a rate of knots.

Talking of melt we have that large berg (from the rammed off Glacial tongue?) to keep an eye on this southern summer though ,so far,fears of it's interference in 're-freeze' appear to have been unfounded?

Hello GW,

Not too sure how I can be misconstruing it. I did quote where he said the it would slow the melt, unless he was mis-quoted or something?
I have no problem with the extra precip "freshening up" the sea surface, allowing for an easier re-freeze. But with all the snow about, falling on the sea ice, would we not just get weak thin ice (like in the Arctic) that melts out quickly and not these large extents we've been getting the last few years?
I just fail to see how one thing can be increasing Arctic sea ice melt yet at the same time be greatly helping Antarctic ice growth. I know they're 2 different systems, but the mechanism by the the extra precip works should be roughly the same in each hemisphere, no?

[Gray-Wolf]

That's my understanding of it NDS, I know the two systems are very different (one an enclosed ocean the other a continent surrounded by ocean) but sea water is sea water isn't it?

As such (along with you?) I can see a 'slush layer' on the surface aiding freezing in the first instance and also that a 'brine filled sponge' of ice would melt out faster but that has to be true in both oceans doesn't it?

If we have increased/augmented precipitation in both areas (north and south) then surely we can apply the same basic physical properties to both areas?

The recent paper discounting that the 'ozone hole' has helped Antarctic by allowing Antarctica to exist in 'splendid isolation' (protected from the general warming) by a faster circumpolar wind and current does have me scratching my Noggin a bit though. If this 'fact'??? is removed then what would explain the current situation?

My time with a lamp and beach volley ball has cleared my head over why things like the mid Holocene optimum was a northern event (and that we can have this 'see saw' effect driven by axial tilt) but what of this when we have a circular orbit and a 'balanced' tilt allowing both north and south equal advantage/disadvantage???

Anyhoo's , as with the 'Greenland mass loss' paper I'll await independent confirmation of these findings (I've not heard the team making the claims about the lack of impact from the hole saying that their evidence is so scant as to render 'replication' of their results impossible) before i re-grapple with the problem (surely the overcoming of the current by basal warm waters and the observation of 'warmer air' above Antarctica confirms that something has been keeping the 'warm out' for 30 odd years?).

So, the only way I can see increased precipitation making a difference to ice levels is by the processes I've outlined (fresh water freezing at higher temps than salt water) and until some tells me this is wrong I'll stay with that!

EDIT: Sorry NDS ,rambling mode!
I haven't managed to see ice hanging around any longer than 'normal'? The high levels of ice seem to melt away in orderly fashion (as we are about to see?)

Edited by Gray-Wolf, 12 October 2010 - 16:52 .

[stewfox]

Gray-Wolf, on 12 October 2010 - 13:27 , said:

If the increased precipitation from the Peninsula extends out into Weddell we could expect to see earlier re-freeze there and an extension of that ice zone into the southern oceans ( thus expanding the 'extent' of ice cover?) The peninsula 'juts out' into the southern ocean and throws the circumpolar currents further out into the southern ocean (and makes some interesting patterns in the waters once the ice melts back with whirls and eddies in that frothy/floury water that remains post melt?)

Have you a link to the last 30yrs of preciption figures across the whole of Antartica and surrounding regions so we can look at the 'theory' for ice growth.

Ice growth isn't restricted to one part

[BornFromTheVoid]

stewfox, on 12 October 2010 - 19:03 , said:

Have you a link to the last 30yrs of preciption figures across the whole of Antartica and surrounding regions so we can look at the 'theory' for ice growth.

Ice growth isn't restricted to one part

This what you're looking for?

[Weather Ship]

A study from 2006.

An international effort to determine the variability of recent snowfall over Antarctica shows that there has been no real increase in precipitation over the southernmost continent in the last half-century.

http://researchnews....ve/antarice.htm

[Gray-Wolf]

Surely both those 'facts' can't be right? Unless, of course, the positive anoms balance out the negatives?

You can see a large anom opposite the tip of the peninsula and ,remembering the Circumpolar current will take the ice from there across Weddell and onward, you can see how this could impact this 'strip' of ocean come re-freeze in April(ish) and 'push out' the extent beyond the protection of the Peninsula (for it to be stripped away come the first storm as we saw with the million loss earlier this season).

[stewfox]

Gray-Wolf, on 13 October 2010 - 08:33 , said:

Surely both those 'facts' can't be right? Unless, of course, the positive anoms balance out the negatives?

Surely ones looking at Antartica (the land mass) the other includes the surrounding oceans where we see greatest varibility.

Whats the varibility in the Artic in the last 50yrs to compare

[Weather Ship]

Interesting. Perhaps the mechanism that caused the Wilkins Ice Shelf collapse.
Elephant seals recruited as field researchers have uncovered new evidence of what may have caused the dramatic collapse of an Antarctic ice shelf two years ago.

Wearing tracking tags, the deep-diving mammals mapped the seabed near the Wilkins Ice Shelf, which is the size of Jamaica but recently began to disintegrate. They discovered channels that deflect warm water towards the ice.


http://www.thetimes....icle2775724.ece

[Gray-Wolf]

http://www.physorg.c...c-seafloor.html

Seemed to need to pay for the Times piece so here is another 'version'.

The 'seals in bath-caps' had been noting an increase in water temps around this coast for a while. up until this the circumpolar current (via the Coriolis affect) had effectively formed a barrier to warm water ingress from the southern oceans so we need to ask "Why now?".

Has the circumpolar current slowed sufficiently to allow ingress or has the temp difference become so marked as to 'tip the balance' and force the warmer water through?

Both scenarios are a worry as this 'warm water' was noted travelling around the coast from the peninsula towards the Ross Embayment. Should similar happen at Ross we could rapidly find out what tolerances the shelf has for frontal loss of the shelf. How much can be 'floated off' by basal melt before the crush of ice from behind pushes the hole of the shelf free?

Though the WAIS is a great concern loss of Ross (or partial loss) frees up the EAIS's main drain glaciers and would drive rapid sea level rise (which in turn would place mechanical pressure on the other ,remaining, shelfs).

[Gray-Wolf]

Here's a fuller report of the feb article on the link between Aussie drought and increased Antarctic snowfall;

http://www.watoday.c...1025-1708s.html

the 750yr record has nothing close to the increases that have been measured over the past 30yrs......odd that, last 30yrs?

[jethro]

There's nothing really odd about having satellite measurements from 30 years ago .....

What's really odd is that the post satellite era is giving us such accurate measurements that we can tell we're in unique times. Couldn't possibly be influenced by not being able to measure with such fine detail, all the various proxy data, could it?

If I were a scientist I think I'd be beginning to ponder on the 30 year coincidences which keep cropping up.

[Yorkshiresnows]

jethro, on 25 October 2010 - 22:21 , said:

<br />There's nothing really odd about having satellite measurements from 30 years ago .....<br /><br />What's really odd is that the post satellite era is giving us such accurate measurements that we can tell we're in unique times. Couldn't possibly be influenced by not being able to measure with such fine detail,  all the various proxy data, could it?<br /><br />If I were a scientist I think I'd be beginning to ponder on the 30 year coincidences which keep cropping up.<br />

<br /><br /><br />

Spot on Jethro,

Y.S

[Blitzen]

http://www.iceagenow...l_on_record.htm

[Weather Ship]

Blitzen, on 26 October 2010 - 09:27 , said:

http://www.iceagenow...l_on_record.htm

Maybe a slight perspective on this.

Reporting in the journal Geophysical Research Letters scientists from British Antarctic Survey (BAS) and NASA say that while there has been a dramatic loss of Arctic sea ice, Antarctic sea ice has increased by a small amount as a result of the ozone hole delaying the impact of greenhouse gas increases on the climate of the continent.

http://www.antarctic...ease.php?id=838

[Optimus Prime]

One minute the Ozone layer was increasing the melt in the Antarctic...now the Ozone layer is preventing a large scale thaw? I have to say the human mind needs more studying then the climate.

[barrel1234]

My common sense siren is going off in my head reading that ozone layer has such a huge impact on Antarctic Ice, I think this is a perfect example of researchers studying a specific thing getting caught up in thinking that its the main driver and having blinkers on to other factors going on in our complex climate.

[Weather Ship]

barrel1234, on 28 October 2010 - 13:50 , said:

My common sense siren is going off in my head reading that ozone layer has such a huge impact on Antarctic Ice, I think this is a perfect example of researchers studying a specific thing getting caught up in thinking that its the main driver and having blinkers on to other factors going on in our complex climate.

I'm not sure I agree with that.
The first comprehensive review of the state of Antarctica’s climate and its relationship to the global climate system is published this week (Tuesday 1 December) by the Scientific Committee on Antarctic Research (SCAR). The review - Antarctic Climate Change and the Environment – presents the latest research from the icy continent, identifies areas for future scientific research, and addresses the urgent questions that policy makers have about Antarctic melting, sea-level rise and biodiversity.


http://www.theozoneh.../ozonehgood.htm

[BornFromTheVoid]

Antarctic ice sheets more stable than first thought?

http://www.newscient...om-the-sea.html

[Gray-Wolf]

BornFromTheVoid, on 21 November 2010 - 18:43 , said:

Antarctic ice sheets more stable than first thought?

http://www.newscient...om-the-sea.html

But only if the whole sheet starts to melt at once.......

And if my uncle had been a woman he'd have been my Aunty.....

As it is we have localised 'melt' and transport and melt across the continent. As we saw from the recent study of shells the passage that separates East and west Antarctica was open (or partially open) 125,000yrs ago so the 'meltdown process' seems to be a process of stages and not a steady, ongoing melt across the whole sheet?

I would guess at ice shelfs disappearing followed by a rapid 'reorganisation of the glacial outlets (once their buttresses have gone) followed by lowland melt revealing the rocks below providing further 'heating' to allow the melt to move upslope.

If this is the process then we will not see isostatic rejuvenation playing the role outlined in the article as the changes are too rapid?

As for isostatic rejuvenation have we heard any more about the paper we had in late spring that said we had over-estimated ice loss from Greenland /Antarctica due to our inability to gauge the rate of uplift as ice mass is removed?

I'd have expected some intensification in studies to prove/dis-prove the contents of the paper?