From a press release provided by Centre national de la recherche scientifique in Paris, France:
Improved estimate of glacier decline in Alaska.
Glaciologists at the Laboratory for Space Studies in Geophysics and Oceanography (LEGOS – CNRS/CNES/IRD/Université Toulouse 3) and their US and Canadian colleagues (1) have shown that previous studies have largely overestimated mass loss from Alaskan glaciers over the past 40 years. Recent data from the SPOT 5 and ASTER satellites have enabled researchers to extensively map mass loss in these glaciers, which contributed 0.12 mm/year to sea-level rise between 1962 and 2006, rather than 0.17 mm/year as previously estimated.
Mountain glaciers cover between 500 000 and 600 000 km2 of the Earth’s surface (around the size of France), which is little compared to the area of the Greenland (1.6 million km2) and Antarctic (12.3 million km2) ice sheets. Despite their small size, mountain glaciers have played a major role in recent sea-level rise due to their rapid melting in response to global climate warming.
Of all the ice-covered regions of the planet, ice loss has been the greatest in Alaska and northwestern Canada, where glaciers cover 90 000 km2. Results from the LEGOS glaciologists and their US and Canadian colleagues, published in the February issue of Nature Geoscience, lead them to conclude that these glaciers have contributed 0.12 mm/year to sea-level rise over the period 1962-2006, rather than 0.17 mm/year as previously estimated by a team at the Geophysical Institute at the University of Alaska (Fairbanks). The new estimate was obtained by comparing recent topographies, derived from Spot 5-HRS (SPIRIT project (2) funded by CNES) and ASTER (GLIMS/NASA project), with maps from the 1950-60s, which enabled loss from three quarters of the Alaskan glaciers to be measured.
How did the team from the Geophysical Institute of the University of Alaska estimate that the contribution of these glaciers to sea-level rise was 0.17 mm/year? In 1995, and then again in 2001, the researchers used an airborne laser to measure the surface elevation of 67 glaciers along longitudinal profiles. These elevations were then compared with those mapped in the 1950s and 1960s. From this, the researchers inferred elevation changes and then extrapolated this to other glaciers. Their results, published in Science (3), pointed to a major contribution to sea-level rise for the 1950-1995 period (0.14 mm/year sea-level rise), which then doubled in the recent period (after 1995).
Why did they overestimate ice loss from these glaciers by 50%? The impact of rock debris that covers certain glacier tongues (4) and protects them from solar radiation (and thus from melting) was not taken into account in the previous work. Moreover, their sampling was limited to longitudinal profiles along the center of a few glaciers, which geometrically led to overestimation of ice loss.
This new study confirms that the thinning of Alaskan glaciers is very uneven, and shows that it is difficult to sample such complex spatial variability on the basis of a few field measurements or altimetry profiles. Thanks to their regional coverage, satellite data make it possible to improve observations of glacial response to climate change and to specify the contribution of glaciers to sea-level rise.
Ice loss from Alaskan glaciers since1962 is evidently smaller than previously thought. However, thinning (sometimes over 10 m/year, as in the Columbia glacier) and glacial retreat remain considerable. Moreover, the spectacular acceleration in mass loss since the mid 1990s, corresponding to a contribution of 0.25 to 0.30 mm/year to sea-level rise, is not in question and proves to be a worrying indication of future sea-level rise.
NOTES:
(1) from Northern Arizona University (US) and two universities in Canada (University of British Columbia and University of Northern British Columbia).
(2) During the 4th International Polar Year (2007-2009), the glaciologists had free access to SPOT 5-HRS data thanks to the SPIRIT project (SPOT 5 stereoscopic survey of Polar Ice: Reference Images and Topographies). The high-resolution images from this satellite can be used to reconstruct precisely the topography of polar ice and thus study its past and future evolution in response to climate fluctuations. LEGOS is the scientific coordinator for this project, which was carried out with CNES, Spot Image and IGN Espace.
(3) Arendt et al, Rapid wastage of Alaska glaciers and their contribution to rising sea level. Science 297, 382-386 (2002)
(4) The lower parts of a valley glacier.
References:
Berthier E., Schiefer E., Clarke G.K.C., Menounos B. & Remy, F. Contribution of Alaskan glaciers to sea level rise derived from satellite imagery. Nature Geoscience, 3(2), 92-95, doi: 10.1038/ngeo737, 2010
Bulldust (16:45:07) :
They love to play the shell game, do they not?
Which is why so many of them are in hot water.
Disingenuity comes at a price.
wayne (16:23:46) :
Rob (14:22:36) :
Woops, mistake in link, others in Rob’s comment.
http://i446.photobucket.com/albums/qq187/bobclive/glacier3.jpg
An overstated difference of 0.05mm/yr, how can this not be natural variability?
When will the stoopidity end!!!!!!
It still won’t save yo from the Green Police!
I don’t think Audi really understands what it is saying in that commercial…
And when I say “really”, I mean REALLY don’t understand!
http://en.wikipedia.org/wiki/Green_Police
Moreover, the spectacular acceleration in mass loss since the mid 1990s, corresponding to a contribution of 0.25 to 0.30 mm/year to sea-level rise, is not in question and proves to be a worrying indication of future sea-level rise.
Since the rate of sea level rise has instead appeared to have slowed* over the past few years, my main conclusion from this “study” would be that the authors need therapy for what is possibly a global anxiety neurosis.
*http://sealevel.colorado.edu/
I was up at the columbia ice fields last summer, they have melted hugely since I was there in the 1960’s, but if you look at the dated stakes in the ground it has melted even more since the mid 1800’s. It would make a great post by someone that can write.
No. It can’t possibly be man-made CO2, look at the dates. Just as much of the receeding was prior to higher CO2 levels than after. I’ll reword the question, could it possibly be the sun or other natural causes?>
There is no doubt that there are natural causes, the question is how much? 1%? 50%? 99%?
That said, I would think that the Sun would be a secondary driver on this issue. Since snow and ice reflect most of the sunshine that hits them, variation in solar flux would have a minor effect in either direction. The larger effect on a glacier’s thickness would be heat transfer from the atmosphere to cause increased melting in the summer, and decreased snow fall in the winter to build it up. You would have to start with both of those factors as primary drivers. The chain of events that affect them though would include solar variation. and ocean currents. and so on.
Well just to check for myself, I went down to the beach this morning and stuck a ruler into the water to check the sea level>
wow humbug, that makes a ton of sense. I am very close to a glacier fed lake, so I zoomed right down there and stuck a ruler in. I figure the water has to go through all kinds of lakes and rivers to get to the ocean, so why not measure at the source instead of several levels down?
I used the time interval as you and got deltas from the mean of 0, 0, 0, 0, and 0. Granted at -27 C the water I am working with is a bit stiffer than yours, but I don’t see where that invalidates the results. I see no trend here to get excited about. Wanna go dibbs on a grant application?
keith in hastings UK (14:58:53) :
quote Surely there are other factors such as evaporation, changes in inputs, thermal expansion, undersea floor changes, maybe even silt run off & so on. Is this all understood & sorted? I’ve not checked but if were a betting man…. happy to be corrected, I may be getting too cynical. unquote
Ocean surface evaporates 120 cms/yr. If you polluted the surface with something which reduced evaporation — I’m sure there must be something which could do it — it would only need to reduce it by 1/7000th.
http://seawifs.gsfc.nasa.gov/OCEAN_PLANET/HTML/peril_oil_pollution.html
JF
Alan H (11:48:33) :
Pretty desperate stuff on the front page of the Independent on Sunday.
http://www.independent.co.uk/environment/climate-change/thinktanks-take-oil-money-and-use-it-to-fund-climate-deniers-1891747.html
Follow the money.
About the Grantham Research Institute.
http://www2.lse.ac.uk/GranthamInstitute/About/about.aspx
Grantham Foundation for the Protection of the Environment.
Hannelore Grantham – co-founder
R. Jeremy Grantham – co-founder
Supportets among many:- Greenpeace and WWF.
http://www.granthamfoundation.org/
Jeremy Grantham is the Chairman of the Board of Grantham Mayo Van Otterloo, a Boston based asset management firm well known among institutional investors, but relatively unknown to retail investors. He’s an investor in various stock, bond, and commodity markets.
Think carbon trading markets.
wayne (16:03:24) :
Wayne,
Agreed, but my point was about the difference between the wording of the Executive Summary and that of the science section, on which the Exec Summary should have been based, (even if the science is wrong.)
********
R. Gates (11:05:42) :
Moreover, the spectacular acceleration in mass loss since the mid 1990s, corresponding to a contribution of 0.25 to 0.30 mm/year to sea-level rise, is not in question and proves to be a worrying indication of future sea-level rise.
*********
Spectacular? Worrying? Alot of hyperbole there. Worrying how, exactly? Have you not seen the graph showing leveling off of sea-level rise in the past ~5-10 yrs that’s been posted here numerous times just recently? That seems to be opposite of what you state.
DirkH (15:07:05) :
DirkH (15:07:05) :
“Rob (14:22:36) :
How about the mass loss here, can`t be CO2 can it.
it.”
You seem to be thinking that CO2 increase causes a rise in temperatures. That’s OK, there are a lot of people like you. But how do the photos prove a causal link that you assume?
Dirk, I was joking mate.
“Roger (15:12:20) :
Anthony, have you seen this report out of Vancouver :
http://www.vancouversun.com/technology/Arctic+vanishing+faster+than+most+pessimistic+models+researcher/2532293/story.html?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed:+canwest/F229+(Vancouver+Sun+-+News)
I haven’t seen an update on the extent of the Arctic ice coverage in a while. I wonder how this claim matches the actual facts.”
I wouldn’t take too much notice of this if I were you. The Scientist in question took an icebreaker to the Arctic and said he saw some rotten ice once. Well woopy f**king doo. (Aliens).
One thing that is somewhat encouraging here is that the effects of debris on the glacier surface are finally being taken into account. A study after the Great Alaska Earthquake of 1964 found a very large change in the dynamics of a glacier resulting from a quake-triggered landslide that covered part of it. Unfortunately the usual simplistic picture of a glacier promulgated by the MSM is that it is just a big, melting ice cube. Of course, a glacier is an extremely complex system affected not only by mean temperature and precipitation, but by a wide range of climatic and geological variables. It also has its own internal kinematics, which can be expressed by glacial “surges”. Well, at least “notice is being taken”.
So, the glaciers are not melting at the predicted “accelerating” rate, in fact they are melting at the same rate that they have since 1820-1850 or so. Indeed, pretty much the average since the last ice age. In the purest terms, despite R.Gates’s pathetic attempts at obsfucation, there is no CO2 effect at all.
I am sure simeone else has pointed out that 0.12mm is about the width of a human hair. Oh and would Ms/Mr Gates care to explain how the Himalayan glaciers are going to melt when there source is considerably below zero? If anything global warming should be causing increased precipitation and the Himalayan glaciers should be growing.
So they estimated ice loss from those glaciers, and they were able to show via radioactive tracers, that every last drop ended up in the oceans, and also that there was nowhere on earth, any increase in evaporation due to the global warming. so all of that melted ice must have resulted in sea level rise; how could it have been otherwise ?
Answer to Mike J (11:35:03) :
You can’t relay on 1950’s mapping. What you can do, and the so called experts should have done had they done their homework properly, is looking closer at photos taken in the past giving that you do have correct day for when they were taken. Anyone skilled in analyzing photos would be able to tell those so called scholars and experts that they have been comparing apples with pinapples and nuts with coconuts. Photos from Alaska as well as taken in for example the Spitsbergen islands do tell a complete different story than the alarmist assumes them to do, given of course that one take the date and month in consideration.
But that doesn’t seem to be the case for most of the so called experts.
It is time to stop taking any notice of these followers of the AGW religion and start to pursue all the money trails.
Time has come to hold them to account for their less than honest endeavours. Anthony has done a wonderful job, some one with financial credentials needs to take up the reins. Hound them until the truth prevails. I have seen enough of these child frighteners to last me a life time. Chase them all right down to the dumb brain washed school teachers, that have been terrifying our children. Wayne Job OZ
“”” davidmhoffer (15:12:59) :
I recently drove the Icefield Parkway from Jasper to Banff, one of the most spectacular drives on earth. You can do it in a little over two hours, but I seriously recommend four.
You pass through the Columbia ice field and glaciers are visible at various points. One of the “toes” of the Athabasca glacier comes right down to the highway. We stopped and I hiked to the face in a few minutes. It had been over twenty years since I last stopped, and the amount the glacier had receded versus my memory was significant. So I decided to ask the old chap what was up.
Me; hey, good to see you again, been a while. Listen chum, its just you and me, no one else around, anything you say is just between you and me. So give it to me straight. Are you receding or not? What’s up with this CO2 thing? “””
Well David, I did the Banff to Jasper in 1967; both ways actually, and we stayed overnight at a little motel on the other side of the hiway from the foot of the Athabasca. As I recall, the ice was damn near to the hiway then (it was mid July), and we went up on it in a sno cat. But it was supposed to be in heavy retreat at the time, so I imagine , in the mean time it had pulled back some from the road. So if it is back to the road again, then there must have been some period of advance.
And I’m with you on the spectacularity of that drive; quite awesome; and the fact that you can pull off the hiway, on either side, literally every foot of the whole distance (140 miles I believe); makes for a breathtaking drive.
I photographed it from end to end. Unfortunately, all 140 or so photos that I took on my Braun Paxette rangefinder camera, were all on top of each other. The sprocket hole tore on the film, and it never advanced a notch.
To add insult to injury, I suspected that something was wrong, so when we were overnighting at Athabasca, I got inside a cloth camera bag and opened the camera, and felt in to see if there was film; and there was; but it was torn. If I had fixed it then, we could have reshot most of the pictures returning to Banff.
We actually were on our way to the arctic circle, up the Alcan Hiway. 11,000 miles in five weeks with three kids in a VW square back Sedan. The real program was to get the family from St Louis Mo, to San Jose California.
Good to know that the Columbia Ice Fields are holding their own, except for the general ice age extraction.
Brian P (21:21:16) :
I was up at the columbia ice fields last summer, they have melted hugely since I was there in the 1960’s, but if you look at the dated stakes in the ground it has melted even more since the mid 1800’s. It would make a great post by someone that can write.
I agree, if you google columbia glacier there is NO information of retreat beyond 1980 which is why Gore used this.
http://i446.photobucket.com/albums/qq187/bobclive/goresfilm.jpg
Peter Miller: The majority of sea level rise is purported to be from thermal expansion. There are many research papers focussed on ocean heat content. Try Google Scholar.