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Greenland - What Do We Know, What Is The Long Term Future And Is There Any Evidence Of A Melt Out?

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Greenland is part of the potential problem of a rise in sea level. What are the problems facing the planet's largest island? Are there real dangers or are we being a little hasty with conclusions?

Discuss............ :)

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I believe that many glaciers in Greenland are in retreat but the majority of the ice cap is still fairly firm - however when ice melts it can form a liquid at the bottom of the ice which allows it to move more easily and quickly. A lot also depends on the topography, so it is more likely to slide off a concave surface than a convex surface.

There will also be the albino effect, or rather the lessening of it - if more ground is left uncovered by snow and ice that ground will experience a greater warming effect in summer, or if there is less of an ice melt in the summer the ice could extend.

The other problem which could affect us would be the melting of fresh water into the North Atlantic, which is lighter than salt water thus slowing down the descent which in turn would slow down the North Atlantic Drift leaving NW Europe in a somewhat fresher climate which could lead to an extension of the glaciers in Scandinavia - I expect that what would happen after that would be anyone's guess except to say that there is bound to be a knock on effect - nothing happens in isolation.

If if were just the polar seas which were to melt there would be no substantial difference in sea levels bcause it is just changing the form of what is already there.

A far big danger as far as sea levels are concerned the melting of the Antarctic ice cap woulds make a far biggerr difference - there are many times more ice there than in Greenland.

But I am not expecting any of these happenings within the next week or so.

Edited by mike Meehan
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I know i've been over this before but , for the new thread, I'll go over it again.

I do not think any ice sheet melts via a slow 'drip ,drip' process alone. I think losses through 'in-situ ablation' , though an important measure, are far from the whole picture. for both greenland and west Antarctic we also have the prospect of basal inundation from the sea and meltout/float off then melt out.

This process is crux as even wth only slow increases in temp you can envisage massive reductions of the sheet forced by mechanical collapse and then transportation into warmer waters to melt.

With greenland we have the central basin (below sea level at present due to isostatic depression) in Antarctica the channel linking Weddel to Ross.

We already know that the majority of glacial losses are driven by the smaller coastal glaciers around Greenland but their larger brethren have an important role to play. Whether it be ever warm Atlantic water incursions or surface melt driving interior degradation (or a bit of both) we have plotted the increase in mass losses from the Greenland ice sheet over the past 20yrs. We have also plotted the retreat , inland, of the grounding line of these glaciers (the point where the glacier rests on the bedrock and is not floating/part suspended , by the ocean.

Radar mapping shows us that the larger Glacial Valleys connect into the central 'basin' under the ice sheet above. Though we have seen some fantastically large bergs calve from the larger glaciers we are re-assured that the ice front is still within historical 'norms'. New mapping techniques have now also allowed us to plot the 'grounding line' and this point of contact is more difficult to 'pin down' as to what is normal or not. you can imagine that the glacier drops it's rocky cargo at the 'grounding line leaving a glacial morraine behind. If the Glacier then advances this morraine would be bulldozed away.

We are told to expect another large calve of Petermann this year .It will not be of the scale of the last one but it will take the calving front beyond the 'normal' advances/retreats of the glacier. Where does this leave the 'grounding line in terms of it spilling into the basin beyond (and 'floating' the ice sheet above?)? At some point, if things continue as we have seen recently, this important event must occur.

We now know that the ice sheet is riddled with caverns and connecting rivers. The added mechanical stresses of such a 'float off' must surely lead to disruption of the pack and further degradation of the ice? Eventualy this 'disruption will reach the surface presenting more ice to the atmosphere and so increasing melt (and so on and so on). It is this 'mechanical collapse' that will bring about 'sudden sea level rises' as the disrupted ice is washed out to sea to melt (leaving more room for continued collapse). this process must have a 'limit' (all the ice will not suddenly 'go') but how much of the Sheet is at risk?

Paleo data shows similar global temps/CO2 levels leaving Greenland with 1/3 less mass/coverage. Is this how we will go from todays ice levels to the new 'rest point'. To me it seems to be the only way for Greenland (and Antarctica) to cause us issues. As we have seen the slow 'drip ,drip' will be far too slow to have any fast impacts. Past oceanic inundations have been fuelled by ice sheet collapse but these have been glacial extensions of the ice sheets we have today. Should we expect any reduction in ice mass in the ice sheets to follow the same mechanisms of the old 'glacial collapses'?

As I've said for me this is the only worrying way that our current ice sheets mass losses could cause us issues.

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Greenland's surface under the ice is not particularly mountainous and the many areas would be below sea level if the ice were not there.

The concept of water lubricating underneath and large reas sliding away does not really apply.

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Greenland's surface under the ice is not particularly mountainous and the many areas would be below sea level if the ice were not there.

The concept of water lubricating underneath and large reas sliding away does not really apply.

?

Are you really saying that the loss of Greenlands ice is a 'nothing' 4?

The very fact that the major Greenland Ice sheet Glacier outlets lie below sea level and the greatest melting is occuring at the base of those glaciers leading to the grounding line inching ever closer to the 'bowl' below the ice sheet is not a worry?

Well then all our learned friends must be wrong and 4 alone correct.

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Well, if things continue the way they are currently going there's only one possible scenario: a rise in sea level and a decrease in albedo. And, IMO, the only result of that situation will be a steep rise in global temperature...Unless, of course, the emphasis gets redirected towards Antarctic melting?

In other words, who knows?

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?

Are you really saying that the loss of Greenlands ice is a 'nothing' 4?

The very fact that the major Greenland Ice sheet Glacier outlets lie below sea level and the greatest melting is occuring at the base of those glaciers leading to the grounding line inching ever closer to the 'bowl' below the ice sheet is not a worry?

Well then all our learned friends must be wrong and 4 alone correct.

Have you lost the ability to read.

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I think you need to imagine the ice sheet a little better then 4? Thick in the middle and thin at the edges. Gravity at a kind of balence due to the ice fused to the base below .Lubricate. Ice in middle spreads like a dollop of treacle on a plate (fragmenting as it goes and floating off into the horizon).

I'm still not understanding you 4?

Edited by Gray-Wolf

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Well, if things continue the way they are currently going there's only one possible scenario: a rise in sea level and a decrease in albedo. And, IMO, the only result of that situation will be a steep rise in global temperature...Unless, of course, the emphasis gets redirected towards Antarctic melting?

It's tricky because melting in parts of the Antarctic (of which there is some evidence) could effect the Themohaline circulation so global temperature rises could well be geographical which has already been noted. But to me it appears that positive feedbacks are beginning to take effect. We may well be past the tipping point.

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Interesting article here - "21st-Century Evolution of Greenland Outlet Glacier Velocities"

ABSTRACT

Earlier observations on several of Greenland’s outlet glaciers, starting near the turn of the 21st century, indicated rapid (annual-scale) and large (>100%) increases in glacier velocity. Combining data from several satellites, we produce a decade-long (2000 to 2010) record documenting the ongoing velocity evolution of nearly all (200+) of Greenland’s major outlet glaciers, revealing complex spatial and temporal patterns. Changes on fast-flow marine-terminating glaciers contrast with steady velocities on ice-shelf–terminating glaciers and slow speeds on land-terminating glaciers. Regionally, glaciers in the northwest accelerated steadily, with more variability in the southeast and relatively steady flow elsewhere. Intraregional variability shows a complex response to regional and local forcing. Observed acceleration indicates that sea level rise from Greenland may fall well below proposed upper bounds.

http://www.sciencema...81/576.abstract

Inappropriate to give a direct link as this is subscription content but it can be found on google scholar -

http://scholar.googl...ved=0CBsQgQMwAA

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Many old landmarks are so changed as to be unrecognisable. Where formerly great masses of ice were found, there are now often moraines, accumulations of earth and stone. At many points where glaciers formerly extended far into the sea they have entirely disappeared.

Taken from an article from the NOAA archive, dated 1922:

http://docs.lib.noaa.gov/rescue/mwr/050/mwr-050-11-0589a.pdf

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Many old landmarks are so changed as to be unrecognisable. Where formerly great masses of ice were found, there are now often moraines, accumulations of earth and stone. At many points where glaciers formerly extended far into the sea they have entirely disappeared.

Taken from an article from the NOAA archive, dated 1922:

http://docs.lib.noaa...50-11-0589a.pdf

It's not completely clear what that's referring to, but it certainly isn't Greenland and is most likely Arctic Norway and/or the Barents and Kara seas.

it is of interest to note the unusually warm summer in Arctic Norway and the observations of Capt. Martin Ingebrigtsen, who has sailed the eastern Arctic for 54 years past. He says that he first noted wanner conditions in 1915, that since that time it has steadily gotten warmer, and that to-day the Arctic of that region is not recognizable as the same re ion of 1865 to 1917.

Many old landmarks are so changed as to be unrecognisable. Where formerly great masses of ice were found, there are now often moraines, accumulations of earth and stone. At many points where glaciers formerly extended far into the sea they have entirely disappeared.

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I know, but I also think this thread has the scope to include all areas of glacial ice in the NH.

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BFTV. Is the chap referring back to LAI conditions in his region as a base-mark?

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BFTV. Is the chap referring back to LAI conditions in his region as a base-mark?

I'm guessing you mean the LIA, and I think we can presume you're right.

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Indeed I do (LOL). so his experience was of how the landscape looked whilst adjusting to those extremes and not how the 'average landscape looked?

Could we have of lot of folk ,of an age to be reporting back then, that had a skewed view of 'average conditions? Dickens himself based his 'winter scenes' on those more typical of his childhood than the time he put pen/quill to paper.

I've always thought that the folk reporting best were those whose life and livelihood depended on the reports of ice edge etc (Whalers/fishermen) and I've not come across any great variance in their reports that would suggest anything like the withdrawal of ice (Baffin/Barrentsz/Kara/Greenland/Bering/Canadian Archipelago/Beaufort/East Siberian) that we see today alongside glacial retreat?

To me folk are relying , out of hope? , on folk whose childhood memories occur at the height of the LIA and not on the data science itself is bringing us?

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Approximately 2-m air temperatures have been measured since August 2005 at NOAA's Greenland Summit 'Baseline Observatory' climate monitoring station (72.58°N, 38.45°W, 3216 m or 10,550 feet above sea level) as shown in this figure.

Here, 1 hour average temperature observations are plotted for the period 1 June through 31 August for 2005-2012. The hourly average air temperature exceeds zero Celsius on 11 July for several hours and almost reaches zero on 12 July. On 10 July and 13-14 July, the hourly air temperature peaks suggest that the surface would very likely have been briefly melting. All five days have peaks well in excess of the NOAA temperature data observed in previous years. A lesser event happened during 28-30 July with a period of brief melting occurring on the 29th.

http://jcet.umbc.edu...ease-green.html

post-12275-0-16772000-1347295373_thumb.j

Edited by knocker

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I can't for the life of me remember whether I've posted these papers elswhere but they should be in here anyway.

Greenland ice sheet albedo feedback: thermodynamics and atmospheric drivers

http://www.the-cryosphere.net/6/821/2012/tc-6-821-2012.pdf

The role of albedo and accumulation in the 2010 melting record in Greenland

http://iopscience.iop.org/1748-9326/6/1/014005/pdf/1748-9326_6_1_014005.pdf

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Early September Greenland ice reflectivity remains low, some melting remains active

While ice sheet average temperatures are declining with the return of the cold season this September, ice sheet reflectivity (a.k.a. albedo) remains anomalously low (Fig. 1). The low albedo values reflect (pun alert) where snow accumulation has not yet covered the darkened surface. There remain some areas where melting remains active at the lowest elevations of the ice sheet (Fig. 2). Melt promotes or maintains low ice reflectivity. Available sunlight in 2012 thus continues to heat the ice and snowpack more than it has in the period of observations beginning in 2000. Less heat will be required to maintain melting or bring the ice to the melting point in the future. It is easy to predict early melt onset in 2013 and a continuation of increasing ice sheet melt rates that contribute to the recently observed net ice loss from Greenland.

http://www.meltfactor.org/blog/?p=783

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Greenland Ice Surface Temperature Monitoring

From Byrd Polar Research Center - Research Wiki

Daily surface temperatures in June-August 2012 have peaked more than 5 C (~9 F) warmer for the whole ice sheet than the 2000-2009 daily averages according to my analysis of ice surface temperatures from daily NASA MODIS MOD11 satellite derived Land Surface Temperature (LST) retrievals. Over the highest elevations, surface temperatures were nearly 10 C (~18 F) warmer than in the 2000′s decade, leading to an area of ice sheet surface melting, unprecedented in the satellite observational record beginning in 1978.

http://bprc.osu.edu/wiki/Greenland_Ice_Surface_Temperature_Monitoring

post-12275-0-50401500-1347986668_thumb.j

Edited by knocker
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I'm so pleased that a goodly number of those 'deniary' types made such a show about the last recorded melt episode in the snow record and pinned a number on the 'cycle' they gleefully claimed. When we see a similar type of event becoming ever more common over the coming years ,as the albedo flip grows, it will be interesting to see them explain it to their faithful? At some point they will be forced to make a 'special case' out of the Arctic melt/Albedo flip based on more than vague claims that it all happened before or become even more out of synch with reality?

For me both the trend in the albedo and the areas under melt has been slowly moveing in this direction for over ten years now, that said it was still a bit of a shock to see it happen so soon?

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Try to explain why Antarctic sea ice is at approaching record levels G W? according to all IPPC previous reports the opposite should be happening.Why is so called global warming not affecting the Antarctic because simply gw isen"t taking place .No doubt we will hearing about the record Antarctic sea melt in the next few months with no mention that the record melt was due to the record sea ice volume.

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Try to explain why Antarctic sea ice is at approaching record levels G W? according to all IPPC previous reports the opposite should be happening.Why is so called global warming not affecting the Antarctic because simply gw isen"t taking place .No doubt we will hearing about the record Antarctic sea melt in the next few months with no mention that the record melt was due to the record sea ice volume.

You'd better run for cover for asking such a question :-D

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