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

[knocker]

In Greenland, scientists who wish to understand ice loss will follow the water. Greenland mass loss is rising exponentially and leading to higher sea level rise.

[Gray-Wolf]

Thanks Knocks! apart from the occasional post noting a cold day in a single location somewhere in Greenland we do not see much in the way of denial of what is occurring there do we? With Global temps still marching upward I'm sure nobody expects a slowdown in melt from the ice sheet? As this ice sheet is a remnant of the last ice age would it not be wise to look to the ablation of other known ice sheets from the last ice age and their ablation to see what we ought to expect , in terms of melt behaviour, from the shrinking of this sheet?

 

What I see is that sea levels rose at differing rates and not at one constant rate? We see well document 'surges' in sea levels in and among the slow melt and I would feel more secure if we knew the mechanisms behind these rapid upticks in sea level rises. Where they representing periods of catastrophic collapse of sections of the sheets ( dropping ice into lower elevations and so into rapid melt) or do they represent the rapid destruction of the lower elevations as albedo plummeted as the earth below began to break through the ice?

 

Whatever the mechanism we need be aware of sudden spurts in melt from our remaining ice sheets and not just plan for the impacts of a slow ,drip ,drip, melt and risk being caught out by the first spurt we encounter?

[4wd]

denial 

Denial of what, the subtext of all the endless posts - with ever more inventive ways to exaggerate ice melting - is a lecturing about how it's all your fault - that is what is not agreed on.

 

Glaciers have been generally retreating since the unusually cold period known as little iceage, but the real deniers don't like to acknowledge that minor inconvenient fact.

The greatest ice loss was in the first half of the 20th Century not recently.

[Gray-Wolf]

You do seem to have a fascination of the pre dimmed period four? Up until the second world war we were seeing the first 'spurt' in warming as both naturals and human forcing began to show impact and I do not think that I've ever come across any 'denial' of those facts?

 

The 'U' turn of northern cooling as we moved into the twentieth century was remarkable in itself but the speed we then warmed should give a feel for how sensitive our global climate is to any extra forcing?

 

The impacts of our pollution on the amount of energy reaching the planets surface, through the 'dimmed period', is not 'new knowledge' and similar impacts now noted from Asia's pollution should always be in our mind when we look at human impacts on climate? If we had a large volcanic eruption, with sulphates ejected into the stratosphere, we would expect global climate impacts over the sulphates lifetime so why don't folk accept the consequences of man made 'eruptions' from both sulphates and particulates?

 

The fact that we see no cooling, even with naturals in negative overdrive, must raise concerns?

 

Back to Greenland. We see large sections of the western fringe of Greenland's ice sheet now free of ice ( no reports of similar from the first spurt of warming from the early 20th Century?) and record flow rates from the rivers over melt season ( again no such record of such outflow from the records stretching back into the early 20th century) should we not be flagging such events?

 

With the planet supposed to be returning to a cooled state under its precessional orbital forcing ( over the far north) why are you expecting us to see further melting? We hit our peak warmth over 8,000yrs ago and so surely you do not think that we have any 'residual warmth' from back then still mounting in the system esp. when temps across the north had been falling for 1,000yrs???

 

As Knocks' link shows we now see a doubling period for melt outflow from Greenland's ice sheet in as little as 5 years so why have we  now started to see such extreme behaviour? Why do we now see ocean terminating glaciers in extreme retreat over the past 30yrs? ( as the time lapse photo's clearly show) and grounding lines retreating up glacier? If all is so hunky dory ( as four appears to believe) why are the experts on the ice sheet in such a tizz about both the changes they measure and the speed of those changes? 

[stewfox]

Thanks Knocks! apart from the occasional post noting a cold day in a single location somewhere in Greenland we do not see much in the way of denial of what is occurring there do we? With Global temps still marching upward I'm sure nobody expects a slowdown in melt from the ice sheet? As this ice sheet is a remnant of the last ice age would it not be wise to look to the ablation of other known ice sheets from the last ice age and their ablation to see what we ought to expect , in terms of melt behaviour, from the shrinking of this sheet?

 

 

 

 

 

The Greenland Ice Sheet gained a record amount of ice and snow this autumn – more than 200 billion tons. This lowers sea level, and is the exact opposite of what experts forecast, and say is happening.

 

http://stevengoddard.wordpress.com/2014/11/30/autumn-greenland-ice-sheet-mass-gain-at-a-record-high/

[knocker]

The Greenland Ice Sheet gained a record amount of ice and snow this autumn – more than 200 billion tons. This lowers sea level, and is the exact opposite of what experts forecast, and say is happening.

 

http://stevengoddard.wordpress.com/2014/11/30/autumn-greenland-ice-sheet-mass-gain-at-a-record-high/

 

Two points regarding that. Professor Jason Box has been studying Greenland for twenty years and currently works for the Geological Survey of Denmark and Greenland (GEUS). I think I would take his opinion over Goddard.

 

The second point quoted from the DMI link

 

 

The figure below shows the total daily contribution from all points on the ice sheet (top) and the same accumulated from September 1st to now (bottom). The blue curves show this season’s surface mass balance in gigatons (Gt; 1 Gt is one billion tons and corresponds to 1 cubic kilometer of water), and for comparison the mean curves from the historical model run are shown with two standard deviations on either side. Note that the accumulated curve does not end at 0 at the end of the year. Over the year, it snows more than it melts, but calving of icebergs also adds to the total mass budget of the ice sheet. Satellite observations over the last decade show that the ice sheet is not in balance. The calving loss is greater than the gain from surface mass balance, and Greenland is losing mass at about 200 Gt/yr.

[knocker]

Subglacial Access and Fast Ice Research Experiment (SAFIRE)

http://www.spri.cam.ac.uk/research/projects/safire/

[knocker]

Greenland melting

 

http://www.rollingstone.com//feature/greenland-melting

[keithlucky]

Greenland ice sheet breaks record ammonts of ice gain this season(300billion tons)with one day in mid September record 12billion tons gains http://beta.dmi.dk/en/groenland/maalinger/greenland-ice-sheet-surface-mass-budget/

[knocker]

Are you actually saying Greenland has gained 300Gt this winter?

[Gray-Wolf]

Seems to be what he is saying knocks? Greenland with all gains and losses balanced out ,shows a surplus of 300Gt this winter????

 

Seems a tad high if you ask me but why would he try and post misleading stats?

[jonboy]

Are you and knocker demeaning KL or the Danish Met from where the figures and details came

[knocker]

Are you and knocker demeaning KL or the Danish Met from where the figures and details came

 

Before you accuse people of demeaning others perhaps you can could show me where the DMI says there has been a 300Gt gain  I merely asked for some clarification.

[PeteG]

I think where KL is wrong is in calling it an "ice gain" as it is described as Surface Mass Balance and as such the vast majority of it will be snow.

[knocker]

It matters not whether it is ice or snow, is there a 300GT gain? It really shouldn't take five or six posts to sort out a simple question.

[Gray-Wolf]

If it is snow then maybe we ought to be concerned?

 

We have seen Greenland suffer some low temps as it slipped into winter this year and this should indicate a lack of precipitation? Are we looking at the impacts of increased moisture in the atmosphere or are we now seeing a kind of 'lake effect' snow from overheated oceans to the west and south of Greenland?

 

The other thing that troubles me is this fluid layer beneath the snow cover ( melt zone that remains fluid). From my understanding of the mechanics of avalanches any asymmetric loading above this 'shear zone' raises the prospect of failure and collapse of the overburden?

 

We see from past inter glacial's that one of the biggest influences on ablation of ice sheets was the dropping of snow/ice from altitude into ablation zones at lower altitudes. Was the increase in air temps instrumental in these losses allowing increased precipitation that brought down, via mechanical failure, sections of the 'saddles' into the lobes below?

 

I constantly see folk using a slow 'drip ,drip' mechanism to envisage the loss of ice sheets and this is surely not natures way of dealing with things? Through nature we see variation in the operating of natural systems so why would ice sheet ablation be any different? For me slow 'melt' is punctuated with periods of rapid ablation ( surges in past sea level rises surely hint at this behaviour?). For this to occur we must see instances of 'catastrophic collapse' where section of the ice sheet not undergoing significant melt rates suddenly find themselves in melt environments. We do not generally see short term spikes in global temps which would hint at a raising of the upper limit of the melt zone so would make far more sense for that ice to find itself transported down slope into active melt regions?

 

In Antarctica any 'float off of sections of Ross would remove it from the slow ablation it currently enjoys and into the southern ocean and rapid melt. The same would apply for section of the upper surface of the Greenland ice sheet should it find itself in the valleys below ( fragmented by the journey from the upper slopes and so presenting far more surfaces to the atmosphere to aid ablation).

 

Surely we all accept we are in a warming world and so that we must see a rationalisation of the amount of ice the planet is able to carry? With temps increasing year on year this figure must also be permanently changing?

[knocker]

Migrating ‘supraglacial’ lakes could trigger future Greenland ice loss

 

Predictions of Greenland ice loss and its impact on rising sea levels may have been greatly underestimated, according to scientists at the University of Leeds.

 

The finding follows a new study, which is published today in Nature Climate Change, in which the future distribution of lakes that form on the ice sheet surface from melted snow and ice – called supraglacial lakes – have been simulated for the first time.

 

http://www.leeds.ac.uk/news/article/3640/migrating_supraglacial_lakes_could_trigger_future_greenland_ice_loss

Edited December 15, 2014 by knocker

[knocker]

2012 remains record year for Greenland ice loss, increasing average global sea level 1.2 mm (eustatic) http://ow.ly/FU1mU 

 

http://polarportal.dk/fileadmin/user_upload/PolarPortal/season_report_2014/PolarPortal2014-EN.pdf

[knocker]

Hidden Movements of Greenland Ice Sheet, Runoff Revealed

 

http://www.nasa.gov/content/goddard/hidden-movements-of-greenland-ice-sheet-runoff-revealed/

[Blessed Weather]

Report published by NOAA Climate.gov on 16th Dec (extracts):

 

Reflectivity of Greenland Ice Sheet in late summer hit new low in 2014

 

The Arctic Report Card: Update for 2014 states that the Greenland Ice Sheet's overall 2014 summer reflectivity was the second lowest (exceeded only by 2012) since MODIS records began in the year 2000.

Greenland Ice Sheet reflectivity has dropped as air temperatures in the Arctic have risen. The Arctic Report Card: Update for 2014 reads, "Data from January-July 2014 suggest that 2014 might become the warmest year in the Arctic since the beginning of the 20th century."

Compared to the 1981-2010 average for surface melting, June-July-August 2014 melt on the Greenland Ice Sheet was above normal across most of the ice sheet. By August 21, 2014, surface melt surpassed the 1981-2010 average by two standard deviations.

 

http://www.climate.gov/news-features/featured-images/reflectivity-greenland-ice-sheet-late-summer-hit-new-low-2014

[keithlucky]

Report published by NOAA Climate.gov on 16th Dec (extracts):

 

Reflectivity of Greenland Ice Sheet in late summer hit new low in 2014

 

The Arctic Report Card: Update for 2014 states that the Greenland Ice Sheet's overall 2014 summer reflectivity was the second lowest (exceeded only by 2012) since MODIS records began in the year 2000.

Greenland Ice Sheet reflectivity has dropped as air temperatures in the Arctic have risen. The Arctic Report Card: Update for 2014 reads, "Data from January-July 2014 suggest that 2014 might become the warmest year in the Arctic since the beginning of the 20th century."

Compared to the 1981-2010 average for surface melting, June-July-August 2014 melt on the Greenland Ice Sheet was above normal across most of the ice sheet. By August 21, 2014, surface melt surpassed the 1981-2010 average by two standard deviations.

 

http://www.climate.gov/news-features/featured-images/reflectivity-greenland-ice-sheet-late-summer-hit-new-low-2014

More fudge data, Greenland ice sheet at a 4 year high and growing fast http://beta.dmi.dk/en/groenland/maalinger/greenland-ice-sheet-surface-mass-budget/

Edited January 17, 2015 by keithlucky

[knocker]

More fudge data, Greenland ice sheet at a 4 year high and growing fast http://beta.dmi.dk/en/groenland/maalinger/greenland-ice-sheet-surface-mass-budget/

 

In your usual rush to accuse everyone of fudging data you forgot this. Quite important when considering albedo

 

[knocker]

Just to clarify my point above although it doesn't really need clarifying.

 

 

http://darksnow.org/

[knocker]

Brief Communication: Sudden drainage of a subglacial lake beneath the Greenland Ice Sheet

 

Abstract. We report on the appearance of a 2 km wide, 70 m deep circular depression located 50 km inland of the southwestern margin of the Greenland Ice Sheet that provides the first direct evidence for concentrated, long-term storage, and sudden release, of meltwater at the bed. Drainage of the lake may have been triggered by the recent increase in meltwater runoff. The abundance of such lakes and their potential importance to the ice sheet's hydrologic system and flow regime remain unknown.

 

http://www.the-cryosphere.net/9/103/2015/tc-9-103-2015.pdf

[Gray-Wolf]

Very interesting Knocks! Helps us 'visualise' where some of that recently discovered 'Sub surface reservoirs' water ends up and what 'dangers' this might bring with it ( especially rapid enlargement of upper level drainage plumbing?),

 

Whatever event kicked off the rapid deflation ( drainage) of the reservoir/lake the results of such pressures along the channels must rapidly widen them? As interconnectivity between drainage fields amass the potential of rapidly draining the summer melt ( instead of being stored in uppland snowpack) must alter the degradation of the Sheet? even if only by introducing 'warm' surface waters to the lower section of the sheet???