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

[knocker]

Abstract.

Forty years of satellite imagery reveal that meltwater lakes on the margin of the Greenland Ice Sheet have expanded substantially inland to higher elevations with warming. These lakes are important because they provide a mechanism for bringing water to the ice bed, causing sliding. Inland expansion of lakes could accelerate ice flow by bringing water to previously frozen bed, potentially increasing future rates of mass loss. Increasing lake elevations closely follow the rise of the mass balance equilibrium line over much of the ice sheet, suggesting no physical limit on lake expansion. Data are not yet available to detect a corresponding change in ice flow, and the potential effects of lake expansion on ice sheet dynamics are not included in ice sheet models.

http://www.the-cryosphere.net/7/201/2013/tc-7-201-2013.pdf

[BornFromTheVoid]

A new website dedicated to Greenland has been created. http://nsidc.org/greenland-today/

In recent years, the surface of the Greenland Ice Sheet has experienced strong melting, but the 2012 melt season far exceeded all previous years of satellite monitoring, and led to significant amounts of ice loss for the year. NSIDC’s new Web site, Greenland Ice Sheet Today presents images of the widespread surface melt on Greenland during 2012 and scientific commentary on the year’s record-breaking melt extent.

Throughout the coming year, the site will offer daily satellite images of surface melting and periodic analysis by the NSIDC science team. NSIDC scientists at the University of Colorado Boulder developed Greenland Ice Sheet Today with data from Thomas Mote of the University of Georgia, and additional collaboration from Marco Tedesco of the City University of New York.

The Greenland Ice Sheet contains a massive amount of fresh water, which if added to the ocean could raise sea levels enough to flood many coastal areas where people live around the world. The ice sheet normally gains snow during winter and melts some during the summer, but in recent decades its mass has been dwindling due to strong melting.

[Gray-Wolf]

One for the 'favourites' for sure! I am quite excited to see what type of year the ice sheet has in 2013 (in an odd macarbre kinda way) as it may be another way of letting folk see just how quickly things are now altering?

I've got a feeling that we might just see a near all red map in July again meaning some folk will have some answering to do about 'cyclical' melt events? Even if not a 97% melt I'm sure the scale will have folk looking pedantic who quibble over a few percent less melt area compared with the old 'average' melt surfaces?

[Thundery wintry showers]

My concern is that as the Arctic increasingly becomes ice-free during the summer months, there will be warmer air masses at low altitudes in the vicinity of Greenland (due to loss of surface albedo) and this may lead to accelerated melting of the Greenland ice sheet (this is probably already contributing to the recent melt).

I haven't looked up papers on this during the past half-year but I remember that quite a few of the papers that I previously dug out suggested that there may well not be a "tipping point" for Arctic sea ice (i.e. assuming that global temperatures stay consistent- an unlikely "if" in this case- the Arctic would probably re-adjust to a new equilibrium), but that a "tipping point" may well exist for the melting of the Greenland ice sheet.

[Gray-Wolf]

Hi TWS!

As long as we have enough warmth to melt the winter snowfall we are in trouble already! What the new 'Greenland site' over spring as the Albedo drops off as the new snow wanes. Last year was a record low and so that 'dirty' surface will just aid further melt and allow it to become even dirtier (and so it goes on!).

This ,in turn, brings us the kind of outflow we saw on the Watson last year and an apparent 5 to 10yr doubling cycle for output (the most worrying aspect!).

We cannot easily remove the Arctic ocean from all off this as we know the loss of sea ice impacts temps 1,500km inland. When we saw the first of the N. Greenland melts we should have realised that the ice loss was beginning to have an impact? As it is once melt commences dust dirt and soot concentrates on the surface increasing it's ability to secumb to solar inputs (instead of reflecting it back into space).

We also have ocean warmth? The lack of ice over Barrentsz (and methane spike there) seems to indicate warmer waters pushing into the Basin via the east of Greenland (and the ocean terminating glaciers seem to confirm this via their melt rates?)

[knocker]

Evolution of the subglacial drainage system beneath the Greenland Ice Sheet revealed by tracers

Abstract

Predictions of the Greenland Ice Sheet’s response to climate change are limited in part by uncertainty in the coupling between meltwater lubrication of the ice-sheet bed and ice flow^{1, 2, 3}. This uncertainty arises largely from a lack of direct measurements of water flow characteristics at the bed of the ice sheet. Previous work has been restricted to indirect observations based on seasonal and spatial variations in surface ice velocities^{4, 5, 6, 7} and on meltwater flux⁸. Here, we employ rhodamine and sulphur hexafluoride tracers, injected into the drainage system over three melt seasons, to observe subglacial drainage properties and evolution beneath the Greenland Ice Sheet, up to 57 km from the margin. Tracer results indicate evolution from a slow, inefficient drainage system to a fast, efficient channelized drainage system over the course of the melt season. Further inland, evolution to efficient drainage occurs later and more slowly. An efficient routing of water was established up to 41 km or more from the margin, where the ice is approximately 1 km thick. Overall, our findings support previous interpretations of drainage system characteristics, thereby validating the use of surface observations as a means of investigating basal processes.

http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1737.html

[knocker]

Significant contribution of Greenland's peripheral glaciers to sea-level rise

The scientists looked at glaciers which behave independently from the ice sheet, despite having some physical connection to it, and those which are not connected at all.

The discovery, just published in Geophysical Research Letters, is important as it will help scientists improve the predictions of the future contribution of Greenland's ice to sea-level rise.

Using lasers which measure the height of the ice from space, and a recently completed inventory of Greenland's glaciers and ice caps, scientists from the European-funded ice2sea programme, were able to determine changes in the mass of those ice bodies, separate from the main ice sheet.

It also showed that the contribution to sea-level rise from the glaciers of Greenland separated from the ice sheet makes up around 10% of the estimated contribution of the entire world's glaciers and ice caps, and that contribution is higher than expected.

http://www.sciencecodex.com/significant_contribution_of_greenlands_peripheral_glaciers_to_sealevel_rise-108719

[Gray-Wolf]

Yet again we see upward revisions of the way Greenland is set to impact us and I suggest it will not be the last such upward revision as we see both the data and behaviour of the ice sheet ,and its glacial outlets, continue to change over time.

Over the past decade we have witnessed a rapid increase in measured losses from the north's largest ice sheet, it now appears we could even be seeing a doubling of losses every 5 to 10 years. This low figure leaves us with the possibility of inches of sea level rise, per year, from Greenland in a little over 30yrs!

When you bear in mind that past warmings has always seen the west Antarctic Ice sheet lead with at least equal amounts of sea level rises from it's melt you can begin to realise that current predictions for sea level rises due to warming may prove tragically low and lead to costs/losses that will prove far more costly to our world economic systems than any preventative measures we could embark on today.

Again I cannot remove the 'forcings' of the Koch Bro's denialist propaganda in removing the type of 'warnings' that should be currently highlighting the dangers we may be facing (they would be labelled 'Alarmist' or 'Doom mongering') and due to our Ozone destroying pollution's we have not seen the W.A.I.S. fore fill it's 'normal' role in leading melt. If we now see the Antarctic Circumpolar's reduce and allow the warming to flood into the Antarctic continent we will see a sudden upswing in losses from there.

[knocker]

With regard to sea level rise GW.

Rising sea levels threaten historic Jamestown, marine geologist says island’s future is grim

http://articles.washingtonpost.com/2013-03-10/local/37605877_1_sea-level-rise-sea-levels-rocky-mountain-climate-organization

[John S2]

sea level threatens whatever bla bla.

Sea level is rising at a rate of 3.2mm/year, as this chart from University of Colorado shows:

http://sealevel.colorado.edu/

[mikeworst]

As it has been the case since the end of the little ice age, and so what exactly?. yes, the average temperature of the globe has been increasing and the sea level probably risen along with it at a modest rate if not in fact a virtally undetectable rate for those at ground level who actually live on the coast.

Have any really low lying islands been inundated in the last 100 years?

Have any coastal areas anywhere experienced a problem with sea level rise in recorded history?

If so please present evidence here.

[John S2]

Have any coastal areas anywhere experienced a problem with sea level rise in recorded history?

If so please present evidence here.

Yes. The inundation of New York due to Hurricane Sandy was made worse by a one foot rise in sea level in that area over the last century:

http://www.climatewatch.noaa.gov/article/2012/superstorm-sandy-and-sea-level-rise

It should also be pointed out that sea level has recently been rising faster than IPCC estimates.

[Gray-Wolf]

Many areas are already 'suffering' due to sea level rise mike? Do you not think the 8" extra may have had impact at Battery Park when Sandy struck? How many inches over did it get to flood out the subway there?

As it stands Greenlands mass loss looks to be doubling every 5 years or so (and set to accelerate) so you can do the math with Greenlands contribution now greater than thermal expansion (2mm last year? so 4mm by 2018, 8mm by 23', 1.6cm by 28' and a whopping 3.2cm by 33').

Now Antarctica is set to come back on line we can also expect to see WAIS losses rival those of Greenland (and if Ross fails then the EAIS will add more than those 2 combined!) over the coming decade meaning that you can bring down the 1"/yr by half.

8" over a century has enabled folk to keep up to the rises but 1" a year???

The noughties saw the london barrage closed how many times compared to the 1990's? 3 times as often? 5 times as often?7 times as often? The data is out there mike, have a gander and then ask yourself 'why?' this occured.

[mikeworst]

I ask again, has any area/country anywhere been compromised by actual sea level rise?. Continental sinking does not count.

[knocker]

Have any really low lying islands been inundated in the last 100 years?

Rising seas, caused by global warming, have for the first time washed an inhabited island off the face of the Earth. The obliteration of Lohachara island, in India's part of the Sundarbans where the Ganges and the Brahmaputra rivers empty into the Bay of Bengal, marks the moment when one of the most apocalyptic predictions of environmentalists and climate scientists has started coming true.

http://www.independe...and-429764.html

A tiny island claimed for years by India and Bangladesh in the Bay of Bengal has disappeared beneath the rising seas, scientists in India say.

The uninhabited territory south of the Hariabhanga river was known as New Moore Island to the Indians and South Talpatti Island to the Bangladeshis.

Recent satellites images show the whole island under water, says the School of Oceanographic Studies in Calcutta.

Its scientists say other nearby islands could also vanish as sea levels rise.

http://news.bbc.co.u...ess/8584665.stm

The island of Male, capital of the Maldives Islands in the Indian Ocean, is at ground zero in Earth's sea level rise dilemma. With a maximum elevation of only 8 feet (2.4 meters), even a modest increase in ocean heights would submerge a majority of its territory. To combat the threat, the government erected a seawall around the entire island.

http://ocean.nationalgeographic.com/ocean/photos/sea-level-rise/

Edited March 19, 2013 by knocker

[mikeworst]

Knocker if you dig a little deeper into that saga and sidestep the hype you will discover that the island in question in transitory and sediment based. It comes and goes despite a ( non existant) sea level rise but is dependant on sediment deposition by the rivers in question.

[knocker]

Interesting photo.

https://twitter.com/...5361025/photo/1

[keithlucky]

Greenland ice melt overestimated due to satelite problems http://nsidc.org/gre...melt-detection/

[Gray-Wolf]

The algoritm used to show surface melt on the new NSIDC map was skewed.....end of.

This does not mean that there is any issue with the usual measurements of mass loss over the summers past just a glitch in the new aid that NSIDC have rolled out for our benefit.

The fact NSIDC have invested in this area would suggest that Greenlands losses are now as important as the rapid reduction in sea ice (with the Sea ice news section and it's daily reports)

The odd thing is that anyone following the data from NSIDC will be aware of the glitch as it was reported first on the site there. As to why anyone else would need to know that this algorythm was out of kilter makes me wonder why here , and other sites, need to be informed unless certain folk are trying to promote doubt in the science?

We saw similar in the way sea ice loss was being measured once it appeared 07's losses were not going to be recovered from (look! Squirrel!) and now we see it in Greenland prior to the onset of the melt season that will question the wisdom of last years mega melt being a 'cyclical freak'. Are folk planting a 'fallback position' for when July brings the inevitable mega melt again? We shall see who , and how many, folk pull this monitoring glitch out in summer as a way to cast doubt on the events we will be witnessing across Greenland then?

[pottyprof]

The algoritm used to show surface melt on the new NSIDC map was skewed.....end of.

This does not mean that there is any issue with the usual measurements of mass loss over the summers past just a glitch in the new aid that NSIDC have rolled out for our benefit.

I agree GW. Nothing wrong with the data. It just needs to be manipulated to correct the errors.

[BornFromTheVoid]

I agree GW. Nothing wrong with the data. It just needs to be manipulated to correct the errors.

There is a difference between the raw satellite data collected and the processing algorithm applied to it. They realised their algorithm was reporting an excess of melt due to an unusual melt layer left after last summer. So they corrected it.

As science does, learns and improves.

[Gray-Wolf]

I think it worth wondering how this 'slush Zone' will impact melt season this year? Surely there comes a point where the 'soaked layers' start to flow under gravity?

Last years papers had picked up on this behaviour in the snow and so 'runoff' must have been impacted? At some point we will 'inherit' the water stored in the snow pack and that will make for an interesting 'mass loss' year?

[pottyprof]

There is a difference between the raw satellite data collected and the processing algorithm applied to it. They realised their algorithm was reporting an excess of melt due to an unusual melt layer left after last summer. So they corrected it.

As science does, learns and improves.

I agree. I wasn't saying anything out of order. There is noise that needs removing from raw data. There's a difference between manipulating data and fudging it to make it fit. It's a new method of collecting data in the whole scheme of things and there will be problems that need ironing out.

My view on data has always been this..........

Raw data should always be made available instead of hiding it and deleting it, as was the case with some data sets. This enables anyone with the know how to work with an untouched source of information. By deleting the raw data, it leaves scientists and statisticians open to accusations of fudging the figures.

Being open about errors actually gives the project a high level of credibility which nobody can argue with. It's a shame that people held it up as being accurate like the French used to hold up heads after the guillotine and caused problems for the team working on this information. It's very rare I comment on new kinds of data because there will always be something that needs correcting and until we know that everything works correctly then it's crazy to accept it as accurate.

[Gray-Wolf]

I think that it's a good thing that circumstances allowed some of the issues to be recognised pre-season? Imagine in a high melt season if they had said' whoa, bit of a glitch here folks......' .

The current climate of disinformation would have grabbed it (as they have done with ice sat data exp. the change from winter to summer algorithms?) and run all season long with it (IMHO).

The page was opened on the back of exceptional events last summer so that we could all watch , near real time, to ongoing changes in the snow/ice cover.

I ,for one, think we will see a lot of use of the site over the coming six months and so am happy to see it monitored and glitches spotted and dealt with.

I do , however, resent folk not being more explicit in their posting when a problem is highlighted (for obvious reasons) and think that this problem was introduced to this thread in a way set to 'misinform/mislead' casual readers?

[clv101]

There's no reason why the loss shouldn't follow an exponential route. It's been a bit warm these last few years. Before long they'll have larger grasslands and be breeding cattle and sheep. Might be good for a weeks break sometime soon. I wonder if they'll open a Viking centre over there?

Greenland is currently losing mass in two ways; surface melting with resulting runoff and iceberg calving from marine terminating glaciers. Over time we can expect some of these glaciers to retreat, pull their feet out of the water and prevent the second of these two forms of mass loss. We need to be careful extrapolating trends when we have recent to believe processes may change.

I'll also add that elevation feedback is likely to become more important as we reach the ice sheet's tipping point. The ice sheet is only there today because it has its head in the clouds, it's a relic of the last ice age. Elevation feedback represents a hysteresis loop, with any significant lowering we can expect increased surface melt.