Via the AGU weekly highlights:
In recent decades, the combined forces of climate warming and short-term variability have forced the massive glaciers that blanket Greenland into retreat, with some scientists worrying that deglaciation could become irreversible. The short history of detailed glacier observations, however, makes pinning the ice loss to either short-term dynamics or long-term change difficult. Research by Young et al. detailing the effects of two bouts of sudden and temporary cooling during an otherwise warm phase in Greenland’s climate history could help answer that question by showing just how heavy a hand short-term variability can have in dictating glacier dynamics.
Along the western edge of Greenland, the massive Jakobshavn Isbræ glacier reaches out to the coast, its outflow dropping icebergs into Baffin Bay during the summer months. Flanking the glacier’s tongue are the Tasiussaq and Marrait moraines-piles of rock marking the glacier’s former extent. Researchers suspected the moraines were tied to two periods of abrupt cooling that hit Greenland 9,300 and 8,200 years ago, and the association was reinforced by the authors’ radiocarbon and beryllium isotope analyses of the area surrounding the moraines. Beryllium-10 forms when cosmic radiation travels through the atmosphere and strikes the Earth’s surface, with surface rock concentrations indicating how long it has been ice-free.
The authors’ analyses show that the moraines were laid down 9,200 and 8,200 years ago, corresponding with periods of sudden cooling. They suggest that the Jakobshavn glacier, which had been retreating prior to the sudden temperature changes, started to grow. At the end of each cold phase, the glacier deposited a moraine before it resumed its retreat. In detailing the sensitivity of the Jakobshavn glacier to short-term temperature change, the study suggests that while the Greenland glaciers’ current retreat is not necessarily irreversible, their extent is tightly bound to the variability of our warming world.
Source: Geophysical Research Letters, doi:10.1029/2011GL049639, 2011
http://dx.doi.org/10.1029/2011GL049639
Title: Response of a marine-terminating Greenland outlet glacier to abrupt cooling 8200 and 9300 years ago
Authors: Nicolas E. Young, Jason P. Briner, Beata Csatho and Greg S. Babonis: Department of Geology, University at Buffalo, Buffalo, New York, USA;
Yarrow Axford: Department of Earth and Planetary Sciences, Northwestern University, Evanston, Illinois, USA;
Dylan H. Rood: Center for Accelerator Mass Spectrometry, Lawrence Livermore National Laboratory, Livermore, California, USA, and Earth Research Institute, University of California, Santa Barbara, California, USA, and Scottish Universities Environmental Research Centre (SUERC), East Kilbride, UK;
Robert C. Finkel: Department of Earth and Planetary Sciences, University of California, Berkeley, California, USA.
Beryllium is producted at the surface of rocks exposed to atmospheric radiation. The amount of beryllium formed is determined by the length of time that the rock has been exposed to atmospheric radiation, so the age of a moraine is the time since the rock was first exposed to radiation when the glacier dumped it on the moraine.
Glaciers seldom retreat at constant rates–they oscillate back and forth with climate changes and thus make good paleothermometers. The most interesting thing about the ages of the glacier terminius shown on the photo is how the 1964 and 2001 positions almost overlap. Off hand, I’d bet that’s because the glacier probably stopped retreating during the climatic cooling of 1945 to 1977 and very likely advanced until the warming after 1978.
What is more alarming:
Retreating ice
Advancing ice
One thing for sure – it will always be doing one or the other. GK
I don’t understand how the glacier has retreated when the photo clearly shows a glacier reaching well past the oldest indicated line of advance?
Owen in GA says:
February 1, 2012 at 7:29 am
. It is generally accepted that the Earth was once ice-free from pole to pole,
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Not only that, but at one time almost the entire earth was iced over.
“Did plants gobble all the CO2 and begin the Ice Age sequence 450-odd million years ago”
Possibly. The Carboniferous Period probably accounted for the loss of a lot of atmospheric CO2 starting around 350 million years ago. There wasn’t enough oxygen for decay as we know it today so the dead biomass simply piled up to become great beds of coal and oil. A lot of CO2 was removed by animals which created the absolutely huge deposits of limestone, too. All of that limestone is CO2 that came out of the air. Same with the shale and marble and alabaster and gypsum. All of that drywall in all of the houses in the world is made from CO2 that came out of the atmosphere.
As for the glacial retreat, what should absolutely amaze them is the LACK of retreat from 1964 to 2001 when the majority of the “global warming” happened. That should completely discredit their hypothesis right there. There was practically no retreat when temperatures were warming the fastest and retreat picked up only when temperatures stabilized. I think they would be better off looking for a precipitation cause, not a temperature cause.
@Vukcevic: BTW: Does anyone know where the GISS temperatures database
http://data.giss.nasa.gov/work/gistemp/STATIONS//tmp. (station.number)/station.txt
has moved to?
To Dante´s Inferno? 🙂
Many other studies show the Greenland glaciers began advancing about 5000 yrs ago, and their advance culminated in the LIA.
http://notalotofpeopleknowthat.wordpress.com/2012/01/21/little-ice-age-coldest-period-in-the-last-7000-years-in-greenland/
Anytime I hear the word “irreversible” regarding planetary systems, I think “careless thinker.” All of it is reversible, all of it will be reversed. There is only one thing that can (will) make the glacier melt irreversible: when the sun becomes a red giant and burns off all the water. Even continental drift towards warmer climes will be reversed eventually.
NASA quotes a total retreat of over 45 kilometers in 159 years, 10 in the past deacde. With a ruler and the satellite image, plus a little calculation using EXCEL, this is distributed as follows per decade:
Decade Retreat (km)
1850 – 1860 2.08
1860 – 1870 2.08
1870 – 1880 4.48
1880 – 1890 4.09
1890 – 1900 2.89
1900 – 1910 3.67
1910 – 1920 2.17
1920 – 1930 2.54
1930 – 1940 3.09
1940 – 1950 2.05
1950 – 1960 3.35
1960 – 1970 1.74
1970 – 1980 0.30
1980 – 1990 0.30
1990 – 2000 0.30
2000 – 2010 10.25
The trend of this is
y = 0.2576x – 474.93
R2 = 0.9711
suggesting a consistent rate of retreat since 1851.
The rapid retreat over the past decade merely makes up for the pause from 1964 – 2001.
When I first got interested in AGW, sometime in the late 1990s, one of the most important factors that made me skeptical was the retreating glaciers. My first reaction was:
-What? Did these people go to school?
My impression was that the AGW proponents were uneducated. I learned in the elementary school (geography) that glaciers are always retreating or growing. ALWAYS! Never still. That’s why the Alps for instance look the way they do. I used to joke that I might start believing in AGW if glaciers stop retreating/growing. Now, that would be unprecedented.
GregO says:
February 1, 2012 at 5:48 am
____________________________
Well said! Excellent points! The only downside to melting ice, as you point out, might be sea level rise. So my advice: if you live in a flood plain you might take some precautions now and sell before the panic happens, and move to higher ground. I personally lived in a flood plain for a number of years and finally moved, not because it wasn’t beautiful and had great canoeing and fishing, but because I got tired of getting flooded and being forced to evacuate every spring and then come home to clean up.
It seems that the illustration at Wiki is different from that at NASA. The latter (at http://www.nasa.gov/101948main_calvingstill_1850_2003.tiff ) is a TIFF image and gives problems in IE9, but if you make a download first and open it in an image program, it works fine. Here you can see it as .jpg file:
http://www.ferdinand-engelbeen.be/klimaat/greenland_glacier.html
The Wiki image probably is from RealClimate and shows some differences, mainly for the year 1953: in the NASA image, the 1953 line is where the 2001 line is in the Wiki image, quite a difference. It may be that between 1953 and 2001 the glacier advanced, because of colder temperatures in Greenland. The temperatures during summer in the period 1935-1950 were higher than in the period 2000-2006 (but I need to make an update for the past years):
http://www.ferdinand-engelbeen.be/klimaat/greenland_temp.html
Further, this is a floating glacier for its tongue. As long as the glacier doesn’t break up, the resistance for the downflowing part from the inland icecap is higher than when the glacier is fragmented and floating in the rest of the icefjord. This increases the flow and the breakup point retreats faster than with a non-fragmented glacier. But there still is resistance as an underwater morene hinders the free outflow of the icebergs at the end of the fjord.
“Chile: Man arrested over glacier ice theft”
http://www.bbc.co.uk/news/world-latin-america-16843905
“Police in the south of Chile have arrested a man on suspicion of stealing ice from the Jorge Montt Glacier.”
So that’s where the ice is going
As some have commented a lot stuff is covered by ice and who knows what is crushed under the ice in Greenland. Is it not better to understand how the planet works over time than to attempt to freeze understanding to the present and call the natural flow of events abnormal.
The attempt to equate the results of climate over tens of thousands and even millions of years to a few decades seems a bit unusual.
In the horse and buggy and lumber wagon days blinders were put on horses and mules so the horse or mule would not be distracted by the surroundings panic and stampede. Now we have the climate change crowd that want blinders on people to limit the view on climate but they want us to panic and stampede to their cause.
I dunno – I look at that glacier with the dates, and if the dates are correct, then that glacier argues totally against global warming (or at least Greenland warming).
Notice how close the two lines are “1964” and “2001”? Think about all those reconstructions from Mann et al and Everyone et al. Wasn’t the 1980s and 1990s the warmest period in the temperature record?
I dare anyone to look at that glacier and point out the Hockey Stick for me.
Right when the warming is warmest, the glacier stopped melting. That is what that photo tells me.
Perhaps we have a Glacier Divergence Problem here.
Anyhow? Some have suggested scientists do not know.
Some say too remote?
What is this with ice anyway?
We have Winter for sure! Things recover – don’t they?
This whole climate change thingy is bull-dust – plain and simple!
Gore-guff – that’s what they all say.
Well let’s put all that a side for just a few moments. On ice so to speak and you all quiet down and hush up – you hear me. Anyone and everybody – you should get yourselves a notebook or lap top or iPad or tablet or PC or whatever – put those “feets” with good coffee brew and have a good read of this. I promise you this – this isn’t your boring dull crap-out about science. It tells us the truth in a narrative that all will LIKE – you okay with that – good.
Why even a good sounding Texan girl (University of Texas) comes into the picture looking at all this stuff.
Right here – have a read……………………………
http://earthobservatory.nasa.gov/Features/Greenland/printall.php
Lesson: Make it real to you. Feel your own humanity. And by all means show a little compassion for our world because we just maybe messing around with it too much lately.
For the Christian Only…….
If you go to Church ask God to show you and direct you as to what is the right thing to do. Don’t just go putting your offering in the bag neglecting that which God may want you to do.
Have a nice day.
In the winter of 2010, Jakobshavn’s ice front did not re-advance as it usually does, so it began the 2010 melt season in the same location as the 2009 summer melt season. As a result, the glacier had the potential to experience significant retreat during the summer of 2010. The breakup in early July 2010 occurred on the northern tributary to Jakobshavn Glacier. The southern tributary actually drains a larger portion of Greenland’s central ice sheet, so a retreat there could lead to a more substantial ice discharge.
Jakobshavn is a large and important glacier, draining over 6% of the Greenland ice cap and more potential sea level rise than any single source in the Northern Hemisphere. It is also one of the most rapidly changing glaciers in the world with thinning rates estimated at up to 15 meters per year. Jakobshavn over the last decade has followed a pattern of calving and retreating, and as recently as July 2010 suffered a significant retreat of ~1.5 km. This very active glacier is the subject of intense amounts of study, so flying the same survey lines several times allows us to determine the pattern of thinning over the entire glacier. This is essential for understanding the processes at work. A surprise result from first two years of IceBridge flights is that the thinning extends much further inland than had been suspected; in fact it extends beyond the limits of our survey. As a result, a second mission to Jakobshavn is planned for this year to extend the survey inland an additional 75 km. When those lines are reflown next year, we will have a more complete picture of the evolution of the glacier. It is findings such as this that have made IceBridge so key to helping us understand the changes in the polar regions.
http://blogs.ei.columbia.edu/2011/04/07/jakobshavn-glacier-continues-to-provide-surprises/
Actually the retreat of the Jakobshavn Isbrae reversed much more recently, in the 1940’s as a matter of fact. There is one data point missing in that illustration at the top. It looks as if the ice retreated, though slowly, between 1931 and 1953. However there is a USAF trimetrogon photograph from 1946 that shows that the ice-front was then in about the same position as in 2001 and that it actually advanced about 5 kilometers between 1946 and 1953.
The photograph is on p. 141 of this paper:
http://rsl.geology.buffalo.edu/documents/csatho_j07j061.pdf
I get 146 km from 1851-1960 which is 146/40 = 3.65 km/decade, and 13 km from 1961-2010 which is 13/5 = 2.6 km/decade. So it’s about 5 km short of “making up” the shortfall. So the next decade needs to melt about 8.6 km. to properly catch up.
🙂 .
From the article (emphasis mine): “Greenland glaciers’ current retreat is not necessarily irreversible, their extent is tightly bound to the variability of our warming world.”
This article is BS and needs no further review.
[Quote]Molon Labe says: I don’t understand how the glacier has retreated when the photo clearly shows a glacier reaching well past the oldest indicated line of advance?[/quote]
I wondered the same thing. The NASA web page hosting the photo says that the photo was taken in 2001, so 2001 line is where the actual glacier extent was at the time. Note that the glacial ice is a bit gray or blue compared to the whiter ice ‘downstream.’ That ice, they say, is seasonally formed sea ice in the glacial fjord, and so not part of the glacier.
Mickey Reno says:
February 2, 2012 at 10:00 pm
The lower part of the glacier is not sea ice but icebergs broken off of the glacier. The year lines show where the break off occurs, but the whole fjord is filled by the floating broken parts of the glacier, because at the end near the sea an underwater morene hinders the icebergs to reach the open water, As the ice (in summer) advances 7 meter per day (!), the gigantic blocks of ice are pushed over the morene wall, but also by wind and tides.
Anyway incredible view (was there in the year 2000)!