You may recall the bogus claim of “97% of Greenland Ice melted”, that was dialed back (REP’s last story on WUWT). Now there’s more of the same sort of stuff. See this PR, and note my bold for the money quote.
From the City College of New York
Greenland melting breaks record 4 weeks before season’s end
Melting over the Greenland ice sheet shattered the seasonal record on August 8 – a full four weeks before the close of the melting season, reports Marco Tedesco, assistant professor of Earth and atmospheric sciences at The City College of New York.
The melting season in Greenland usually lasts from June – when the first puddles of meltwater appear – to early-September, when temperatures cool. This year, cumulative melting in the first week in August had already exceeded the record of 2010, taken over a full season, according to Professor Tedesco’s ongoing analysis.
“With more yet to come in August, this year’s overall melting will fall way above the old records. That’s a goliath year – the greatest melt since satellite recording began in 1979,” said Professor Tedesco.
This spells a change for the face of southern Greenland, he added, with the ice sheet thinning at its edges and lakes on top of glaciers proliferating.
Professor Tedesco noted that these changes jibe with what most of the models predict – the difference is how quickly this seems to be happening.
To quantify the changes, he calculated the duration and extent of melting throughout the season across the whole ice sheet, using data collected by microwave satellite sensors.*
This ‘cumulative melting index’ can be seen as a measure of the ‘strength’ of the melting season: the higher the index, the more melting has occurred. (The index is defined as the number of days when melting occurs multiplied by the total area subject to melting.)
Dr. Thomas Mote, Professor of Geography at the University of Georgia and colleague of Professor Tedesco, confirmed that the cumulative melt in 2012 had surpassed that of 2010 using a similar analysis.
The August 8th record differs from NASA’s announcement of unprecedented melting in mid-July, reported by Professor Tedesco and other researchers. Then, they found that the Greenland ice sheet had melted over 97 percent of its surface.
“That event was exceptional in the sense that it was an extremely rare event,” said Professor Tedesco. “Imagine Rio de Janeiro under a layer of snow and you get the idea.”
The extreme melting detected in mid-July, on the other hand, generated liquid water that refroze after a few days. “This changed the physical properties of the snowpack – making a slushy layer that turned into an icy crust after refreezing – but very likely it did not add to the runoff of meltwater that makes sea levels rise.”
The cumulative melting index, on the other hand, does account for water flowing to the ocean. The same meltwater can affect ice dynamics by lubricating the base of the ice sheet and speeding its slide toward the sea.
This year, Greenland experienced extreme melting in nearly every region – the west, northwest and northeast of the continent – but especially at high elevations. In most years, the ice and snow at high elevations in southern Greenland melt for a few days at most. This year it has already gone on for two months.
“We have to be careful because we are only talking about a couple of years and the history of Greenland happened over millennia,” cautioned Professor Tedesco. “But as far as we know now, the warming that we see in the Artic is responsible for triggering processes that enhance melting and for the feedback mechanisms that keep it going. Looking over the past few years, the exception has become part of the norm.”
* The National Snow and Ice Data Center provided satellite data from the United States Air Force Defense Meteorological Satellite Program.
The NASA Cryospheric Sciences Program and the National Science Foundation (NSF) sponsored this research.
Note: An upcoming paper submitted by Professor Tedesco and his colleagues examines the losses and gains that the Greenland ice sheet could experience, as projected through the end of the 21st Century according to different CO2-level scenarios.
Online:
Greenland Melting www.greenlandmelting.com
Video: Bridge destruction over Watson River, Greenland, likely a consequence of cumulative melting. (Filmed by M.Tedesco) http://www.youtube.com/watch?v=kKjXKAatiIs
NASA Release: Satellites See Unprecedented Greenland Ice Sheet Surface Melt http://www.nasa.gov/topics/earth/features/greenland-melt.html
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This quote…
“That event was exceptional in the sense that it was an extremely rare event,” said Professor Tedesco. “Imagine Rio de Janeiro under a layer of snow and you get the idea.”
In juxtaposition with this one:
“That’s a goliath year – the greatest melt since satellite recording began in 1979.”
…has to be one of the most ridiculous ones I’ve ever seen.
How rare? Well professor, show me the records of such melts prior to satellite monitoring and you might have an argument. Greenland melts every summer. How many summer in the past 1000 years have such levels of melt? I don’t think he can tell us. Is a 1 in 30 year event “rare”?
As for the reason, I think this figures in:
I refer you to this photograph of a Moulin in Greenland:
http://wattsupwiththat.com/2010/11/03/greenland-ground-zero-for-global-soot-warming/
Image from National Geographic online slide show – Photo: James Balog – click for moreBalog writes:
In the winter a huge among of snow are accumulated on the Ice (2-3 meters, sometimes more) and we are not talking about 1 or 2 square-miles, it’s about 100.000′s of square miles (up to 1 million) on the Westside of the Ice cap and a similar picture on the Eastside… when the melting season starts in april-sep… the meltwater has to go somewhere, and for sure it goes downhill in huge meltwater rivers.
The black stuff on the bottom of the lakes is carbon dust and pollution in general… but not from one year, but several decades (the topographical conditions don’t change from year to year). On a flight over the Ice Cap a sky clear day, you can see hundreds of huge lakes with the black spot on the bottom.
See this experiment with soot on snow done by meteorologist Michael Smith of WeatherData where soot made a huge difference.
izen:
re. your post at August 17, 2012 at 3:07 am.
Please see the above exchange between Ferdinand Engelbeen and myself.
There is nothing unusual in the recent melting of the Greenland Ice Sheet.
Melting and refreezing is a common event.
Also, in addition to your false claim that recent melting of the Ice Sheet is unusual, your post makes personal remarks. Until the paid troll made deliberately misleading remarks all my posts in this thread were directly pertinent to the subject of the thread. I then posted to object to the nature of those remarks and I made one – only one – post to inform about the troll.
And you have been told not to abuse me with diminutives.
Richard
The Greenland ice-sheet temperature is -32C immediately below the surface. It stays that temperature for about 1500 metres down and then it slowly warms up until bedrock is reached where it is -2.7C and it melts given the higher pressure.
http://ars.sciencedirect.com/content/image/1-s2.0-S0277379104002689-gr3.jpg
http://www.eos.ubc.ca/research/glaciology/research/Publications/LhommeClarkeMarshall(QSR-2005).pdf
The snow that fell on Greenland during the Holocene is 600 metres down and the snow that fell during the last glacial maximum is 1300 metres below the surface. It accumulates every year despite a few days each two years that get above 0.0C.
The ice at the bottom of the ice-sheet is only 120,000 to 130,000 years old and the temperature at the bottom of the ice-sheet is -2.7C which is enough to melt the 125,000 year old ice when it gets there. It slowly trickles as water now to low points on the Greenland bedrock (potentially making it to the ocean in a few places – potentially staying as rock-hard-wet-water-ice in other places). One new drill-site, NEEM, at a northern summit might have the only non-melted ice at the bottom.
So, Greenland does not melt from the top, it melts from the BOTTOM [and from the SIDES which are continually replenished from ice flow from the summit high points].
That is the science. Not this +1.0C 4 melt day garbage being foisted onto the warmers minds of late.
Updated link.
http://www.eos.ubc.ca/research/glaciology/research/Publications/LhommeClarkeMarshall(QSR-2005).pdf
izen says:
August 17, 2012 at 3:07 am
Bill Illis says:
August 17, 2012 at 6:30 am
If one of you can give me volumes relased from the Greenland ice cap by the recent event, annually or decadally for recent years I can estimate the effect on sea levels.
izen says:
August 17, 2012 at 3:07 am
The rate of melting in Greenland has already accelerated over the last decade, this even greater rate of melting this year comes on top of this. Claiming that pointing this put is ‘hype’ seems to be based on a desire to minimise the observed acceleration and reject the implications of even greater rates of melt this year.
The problem is that there were no satellites before the ’70s of the past century. But the melt in the period 1935-1955 was as huge as today, as far as can be deduced from altimetry and old aereal photo’s: some 70 meter reduction of the ice sheet height at the Jacobshavn/Illulisat glacier over a few decades, going far into the main ice sheet. The current peak melt of a few days even at the summit happened too some 150 years ago, as could be measured in the Greenland ice cores. Thus there is not reason for panic, we still are within natural variability.
Melting of the ice sheet at the edges is mainly a matter of temperature. There are several stations around Greenland which show higher summer temperatures in the period 1935-1955 than current:
http://www.ferdinand-engelbeen.be/klimaat/greenland_temp.html but I need to do an update of the graph for the most recent years.
The breakup point of the largest Greenland glacier is retreating since before 1850, but there was a large retreat around 1950 and after that again advancing (together with a cooler climate) and since 1990 again a retreat. Thus nothing unusual there, simply natural variability:
http://www.ferdinand-engelbeen.be/klimaat/greenland_glacier.html
Entropic man says:
August 17, 2012 at 9:18 am
Here is the latest most sophisticated model. It is still draft for discussion.
http://www.the-cryosphere-discuss.net/6/2789/2012/tcd-6-2789-2012.pdf
Bill Illis says:
August 17, 2012 at 11:51 am
Here is the latest most sophisticated model. It is still draft for discussion.
http://www.the-cryosphere-discuss.net/6/2789/2012/tcd-6-2789-2012.pdf
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They are allergic to complex models here. I think we’ll try arithmetic instead.
http://www.agu.org/pubs/crossref/2011/2009JB006847.shtml
Schrama et al 2011 used GRACE data to measure ice loss from the Greenland ice sheet. (see Figure 2). They found a loss between March 2003 and February 2010 of 1512 gigatons, 252 Gt per year.
A gigaton is one billion tons of ice, one cubic kilometre.
The surface area of Earth is 510,000,000 square kilometres of which 71% or 360,000,000sq.km. is ocean.
To raise the surface of 1 sq.km of ocean by 1mm would need 1/1,000,000 cubic kilometres of water. To raise the level of the entire ocean by 1mm would need 360,000,000/1,000,000 =360 cubic kilometres.
The annual sea level rise due to Greenland ice loss is therefore 252/360 = 0.7mm/year.
That is 4.2mm over the six years of the study.
If we accept the figure of 180mm/century quoted elsewhere, that is 1.8 mm’/year and Greenland contributes 39% of the sea level rise.
If the sceptics are right, that this melting rate is normal and will continue unchanged or even slow, we have no need to worry. If the consensus is right and ice sheet melting is due to accelerate, then we may have problems.
Oh, for a time machine!
Friends:
Ferdinad Engelbeen says in his fine post at August 17, 2012 at 11:03 am
The paid troll says at August 17, 2012 at 1:01 pm
I say
If the consensus is right and pigs are due to learn to fly then we may need reinforced umbrellas.
Richard
The southern third of Greenland is too far south to have an ice-sheet. The summer solar insolation is too high to allow glaicers to build up. The only reason the ice-sheet is there is because of the ice accumulation in the centre/north during the ice ages.
If the interglacials last for 20,000 to 25,000 years, the southern third of Greenland melts out and the centre/north height will drop by 500 metres or so.
The last time this happened was the interglacial at 400,000 years ago, which was not a particularly warm one (less than current temperatures probably), and the southern third of Greenland melted out and small trees even grew there.
The Greenland ice-sheet has been shrinking since the last glacial maximum and will continue to do so for 50,000 years or even 120,000 years (when the Milankovitch Cycles turn low enough for the next ice age to begin – they don’t until then).
So, 0.3 mm/yr (the correct figure) of sea level rise was going to happen regardless of the CO2 level in the atmosphere.
That is the science .
David G says:
August 15, 2012 at 5:27 pm
> Tez, the Vikings didn’t farm in Greenland for 500 years, not even close.
References?
Barry Fagan, in his “The Little Ice Age” gives 980s – mid 1300s:
They had the land to themselves, a place where the green summer pastures and thick willow scrub offered pasture and fuel. The summers were brief and fairly warm, with longer days than Iceland. The winters were long and harsh, but the Norse were accustomed to climatic extremes. They found much better grazing land than at home, abundant fish and sea mammals, and edible birds aplenty. Eirik sailed back to Iceland with glowing reports of a land so fertile he named it Greenland, “for he said that people would be much more tempted to go there if it had an attractive name.”
…..
For five centuries, Europe basked in warm, settled weather, with only the occasional bitter winters, cool summers and memorable storms, like the cold year of 1258 caused by a distant volcanic eruption that cooled the atmosphere with its fine dust. Summer after summer passed with long, dreamy days, golden sunlight, and bountiful harvests. … Nothing prepared them for the catastrophe ahead. As they labored through the warm summers of the thirteenth century, temperatures were already cooling rapidly on the outer frontiers of the medieval world.
…..
The Norse could usually survive one bad summer by using up the last of their surplus the following winter. But two successive poor hay crops placed both the animals and their owners at high risk, especially if lingering ice restricted summer hunting and fishing. The ice-core analyses for 1343 to 1362 reveal two decades of much colder summers than usual. Such a stretch, year after year, spelled disaster.
… All the dog bones at the manor farm came from the final occupation layer and displayed the butchery marks of carcasses cut up for human consumption. Having first eaten their cows and then as much small game as they could take, the Nipaatsoq families finally consumed their prized hunting dogs.
… The Norse kept a foothold at the warmer Eastern Settlement for another 150 years. …
980s to late 1200s (I left that out) + 150 = about 450 years.
Yeah, I was surprised the settlements were there for so long myself.
Except that it’s not the same. Here’s a simple demo why: scatter gravel on a patch of concrete in poor condition, in sub-freezing temps. Spray with water to make a thin layer of ice. Now go skate on it.
After about the 10th severe face-plant, perhaps you’ll get it.
The rock below a glacier is no smooth, flat, prepared surface. It is jagged and debris-covered, with ridges and valleys crosscutting it. It does not permit sliding. Nohow. When a glacier moves, it GRINDS, it doesn’t “slip”.
I live in Northern Ireland, a glacially eroded landscape and see various effects.. On the hills under the original centre of the ice sheet you often get the rough surface you describe (locking the ice in place at the base but allowing it to flow nearer the surface), plus corries where a patch of ice maybe a mile across has rotated and ground a hollow beneath it.
Further out, along the paths of the glaciers, you see quite smooth surfaces on the bottom and sides of the U-shaped valleys where the material carried by the ice has ground away the surface. You even see enormous gouges where a boulder in the ice has scraped along the valley, tearing chunks away from the surrounding rock as it went. Glacial erosion can be savage!
When the ice sheet melts it leaves behind eskers, drumlins, morraines and kettleholes where material eroded along the way has been dumped by melting ice or carried in meltwater.
I love glaciers, ever since Geography classes.
Bill Illis says:
August 17, 2012 at 4:49 pm
The southern third of Greenland is too far south to have an ice-sheet. The summer solar insolation is too high to allow glaicers to build up. The only reason the ice-sheet is there is because of the ice accumulation in the centre/north during the ice ages.
If the interglacials last for 20,000 to 25,000 years, the southern third of Greenland melts out and the centre/north height will drop by 500 metres or so.
The last time this happened was the interglacial at 400,000 years ago, which was not a particularly warm one (less than current temperatures probably), and the southern third of Greenland melted out and small trees even grew there.
The Greenland ice-sheet has been shrinking since the last glacial maximum and will continue to do so for 50,000 years or even 120,000 years (when the Milankovitch Cycles turn low enough for the next ice age to begin – they don’t until then).
So, 0.3 mm/yr (the correct figure) of sea level rise was going to happen regardless of the CO2 level in the atmosphere.
That is the science .
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Melting ice sheets raise sea level 1mm per 360 cubic kilometres released. (August 17th, 1.01pm).
Simplify your estimated melting to a 500M decrease in thickness across the whole ice sheet of 1,710,000sq. km.This would release 1,710,000/2 = 855,000 cu. km of water.
The sea level rise would be 855,000/360 = 2375mm or 2.375 metres.
If that happened gradually over the rest of the interglacial, say 20,000 years, the rise would be 2375/20,000 = 0.12mm/year from Greenland (entirely consistent with your 0.3mm/yr).
Unfortunately, instead of the 855000/20000 = 42.75 cu km/yr you project, the current loss rate has been measures at 252 cu.km/yr (schrama et all 2011, see my 1.01pm comment). This gives a sea level rise of 252/360 = 0.7mm/yr, over twice your figure for melting from Greenland alone.
At present the ice sheet seems to be losing mass about five times faster than your model predicts. Whether this is temporary or ongoiing is a discussion for another time.