From the University of Innsbruck, another modeling study.
This news release is available in German.
The ongoing global glacier retreat causes rising sea-levels, changing seasonal water availability and increasing geo-hazards. While melting glaciers have become emblematic of anthropogenic climate change, glacier extent responds very slowly to climate changes. “Typically, it takes glaciers decades or centuries to adjust to climate changes,” says climate researcher Ben Marzeion from the Institute of Meteorology and Geophysics of the University of Innsbruck.
The global retreat of glaciers observed today started around the middle of the 19th century at the end of the Little Ice Age. Glaciers respond both to naturally caused climate change of past centuries, for example solar variability, and to anthropogenic changes. The real extent of human contribution to glacier mass loss has been unclear until now.
Anthropogenic Causes
By using computer simulations of the climate, Ben Marzeion’s team of researchers simulated glacier changes during the period of 1851 and 2010 in a model of glacier evolution. “The results of our models are consistent with observed glacier mass balances,” says Marzeion. All glaciers in the world outside Antarctica were included in the study. The recently established Randolph Glacier Inventory (RGI), a complete inventory of all glaciers worldwide, enabled the scientists to run their model. “The RGI provides data of nearly all glaciers on the Earth in machine-readable format,” explains Graham Cogley from Trent University in Canada, one of the coordinators of the RGI and co-author of the current study.
Caption: This image shows the Artesonraju Glacier in Cordillera Blanca, Peru.
Credit: Ben Marzeion
Since the climate researchers are able to include different factors contributing to climate change in their model, they can differentiate between natural and anthropogenic influences on glacier mass loss. “While we keep factors such as solar variability and volcanic eruptions unchanged, we are able to modify land use changes and greenhouse gas emissions in our models,” says Ben Marzeion, who sums up the study: “In our data we find unambiguous evidence of anthropogenic contribution to glacier mass loss.”
Significant Increase in Recent Decades
The scientists show that only about one quarter (25 +/-35 %) of the global glacier mass loss during the period of 1851 to 2010 is attributable to anthropogenic causes. However, during the last two decades between 1991 and 2010 the fraction increased to about two thirds (69+/-24%). “In the 19th and first half of 20th century we observed that glacier mass loss attributable to human activity is hardly noticeable but since then has steadily increased,” says Ben Marzeion. The authors of the study also looked at model results on regional scales. However, the current observation data is insufficient in general to derive any clear results for specific regions, even though anthropogenic influence is detectable in a few regions such as North America and the Alps. In these regions, glaciers changes are particularly well documented.
The study is supported, among others, by the Austrian Science Fund (FWF) and the research area Scientific Computing at the University of Innsbruck.
A thousand observations may appear to verify a hypothesis, but one critical failure could result in its demise.
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agreed. A stopped clock is right more than 700 times a year. It is the times that it is wrong, not the times that is right that are important.
As per IPCC about 50% of the raise in global temperature is attributed to anthropogenic greenhouse gases increase in the atmosphere since 1951. That means the base year of global warming is 1951. Since then the global warming is less than 0.2 oC. Then the question is will sich temperature has any effect on sea level rise or glacial melt??? There are several other factors that contribute to glacial melt — human direct influence [nuclear tests, wars, oil & gas drilling, tourism/sports, dams construction, deforestation, etc and natural hazards such as earthquakes & Volcanoes, etc
Dr. S. Jeevananda Reddy
Joel O’ Bryan @ur momisugly 9:27 pm
You mentioned the Mesa Verde Cliff Dwellings near Cortez, CO. I have relatives in the Mancos Valley near there and in the 1960’s we would visit them and stop by Mesa Verde. As children we liked climbing up and down the cliffs.
It was told that the cooler/drier climate that existed then would cause droughts that would last for a century or more. This was given for the explanation of their abandonment. It’s a shame that they would change that without evidence to contradict it.
Curious George says:
August 15, 2014 at 12:53 pm
“There is a plenty of similar “research” reported… Today’s university is what used to be called a high school a century ago”
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No, they used to be called a Theological Seminary. Now, it’s the ‘Progressive Bible’ that is used for indoctrination at our state-sponsored seminaries. No funding if they don’t teach official doctrine.
I am struck by how many have not watched an ice-cube melt.
Why does he call his model output data?
“While we keep factors such as solar variability and volcanic eruptions unchanged, we are able to modify land use changes and greenhouse gas emissions in our models,” says Ben Marzeion, who sums up the study: “In our data we find unambiguous evidence of anthropogenic contribution to glacier mass loss.”
“In our data we find”?
Should it not be in our model conjecture we surmise?
Ben meet Sophie. Sophie meet Ben.
Edward Richardson “All your link shows is that the 6-month variation is due to summer-winter changes in CO2 absorption due to the uptake of CO2 in the Northern Hemisphere in summer.”
Having done the simple process to check data against your statement. I blew up the curves and looked at them in 5 year increments. Sorry there is nothing like a 12 month cycle here. Again on close examination, some cycles are short, some are several years, vast majority are nowhere near yearly. Wonder where you got that idea.
See for yourself http://www.woodfortrees.org/plot/esrl-co2/isolate:60/mean:12/scale:0.2/plot/hadcrut3vgl/isolate:60/mean:12/from:1958
“Since the climate researchers are able to include different factors contributing to climate change in their model, they can differentiate between natural and anthropogenic influences on glacier mass loss. “While we keep factors such as solar variability and volcanic eruptions unchanged, we are able to modify land use changes and greenhouse gas emissions in our models,” says Ben Marzeion, who sums up the study: “In our data we find unambiguous evidence of anthropogenic contribution to glacier mass loss.””
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At least there is one thing to appreciate here.
The word used is “contribution” instead of the “causing” climate change.
There is a huge difference inbetween.
ACC-AGW is all about causality not contribution.
Basically it means that while we are contributing to the greenhouse effect, we are not actually changing it’s natural atribute of amplifying the warming, or more precisely it’s natural attribute of stabilazing the climate change.Therefor we not causing any climate change.
Simply it states that while anthropogenic forcing is contributing to a kinda of warming, that warming has not been started or caused from the ARF. For the luck of better word that is a had-on contradiction to the AGW-ACC.
cheers
CMS says:
August 16, 2014 at 8:38 am
…
I like your data plot.
I modified it slightly
..
http://www.woodfortrees.org/plot/esrl-co2/isolate:60/mean:12/scale:0.2/trend/plot/hadcrut3vgl/isolate:60/mean:12/from:1958/trend
Wonderful correlation you have in that data.
Fit of pique for being caught out. Sorry about that inconvenient truth.
CMS says:
August 16, 2014 at 9:47 am
” inconvenient truth.”
Better take a second look at this….
http://www.woodfortrees.org/plot/esrl-co2/isolate:60/mean:12/scale:0.2/trend/plot/hadcrut3vgl/isolate:60/mean:12/from:1958/trend
…
Because due to your “Isolate 60” and “mean(samples) 12” has altered the HADCRUT3 data beyond recognition.
..
http://www.woodfortrees.org/plot/hadcrut3vgl/from:1958/trend/plot/hadcrut3vnh/from:1958
The actual trend is positive (second link) and your processing turned it negative (first link)
From Berthold Klein on August 15, 2014 at 1:14 pm:
From cleanwater2 on August 15, 2014 at 1:19 pm:
Second nut quoting the first nut just 5 minutes later, and neither provides a link?
Who else believes that’s the same guy?
CMS says:
August 16, 2014 at 9:47 am
PS….
Here is the how CO2 data depends on time of year
http://www.woodfortrees.org/plot/esrl-co2/from:1999
see the ‘wiggle?”
CMS:
Make the scale factor 0.26. It works a little better:
http://www.woodfortrees.org/plot/esrl-co2/isolate:60/mean:12/scale:0.26/plot/hadcrut3vgl/isolate:60/mean:12/from:1958
kadaka,
No doubt it’s the same guy.
Edward Richardson Because you can’t respond, are you being intentionally obtuse. No one but you believes, and I find it hard to believe even you really think the graphs that I posted are about a trend and yes I am quite familiar with yearly variations. This is about what leads, the temp or CO2 since 1958. And once again, if you look at it in 5 year increments, there is absolutely nothing about this data that suggest that it is an annual phenomena.
http://www.woodfortrees.org/plot/esrl-co2/isolate:60/mean:12/scale:0.2/plot/hadcrut3vgl/isolate:60/mean:12/from:1958
Always happy to display this data again, because it really is quite interesting
Edward Richardson says:
“However, I want you to address the data point at both the GNP and the Swiss Alps that falsify your hypothesis.”
Have you ever considered the fact that the age of tree stumps uncovered by glaciers does not indicate the time the area was last ice-free, but the last time the area was ice-free and warm enough for forest to grow there. I’ve visited glaciers in fifteen countries on five continents and it is actually quite rare for forest to grow right up to the glacier front. It only occurs at glaciers at middle latitudes which have a large accumulation area with heavy precipitation and a narrow front and which can therefore push down to an altitude low enough for trees to grow.
I have only visited a few of the glaciers in GNP, but none of the ones I’ve seen there are in this category (they are to small for one thing). Historical data shows that there were a few such glaciers in the Alps during the LIA (e. g. untere Grindelwaldgletscher), but I strongly doubt that there is any now, I’ve certainly never seen one.
Such conditions are of course much more likely to occur during periods of glacier expansion than during retreat, since forest treees are capable of surviving for long periods in conditions too harsh for new trees to be able to establish, sometimes even until being overrun by a glacier.
As rgbatduke has comprehensively explained here more than once, climate science is an illusion. We dont know what changes climate. And the fact that current alarmist climate science is predicated on the assumption that a change in climate is something unusual and threatening underlies the totality and profundity of that ignorance. To achieve this colossal pinnacle of ignorance has taken decades of hard work both undermining and destroying the existing edifice of scientific knowledge and also destroying the Popperian philosophical basis and logical integrity that a few decades ago were the foundation of the practice of science.
Not only do these authors claim without basis to understand why glaciers have recently receded, but they claim the be able to split hairs and establish a percent of human attribution. Again the underlying and absurd assumption is that there is something unusual and problematic about changing extent of glaciation.
Edward Richardson:
In your post at August 16, 2014 at 9:36 am you say
They do not correlate. They cohere.
CMS said and showed they cohere
http://www.woodfortrees.org/plot/esrl-co2/isolate:60/mean:12/scale:0.2/plot/hadcrut3vgl/isolate:60/mean:12/from:1958
But I would not expect you to know or to understand the difference.
Richard
I couldn’t get the paper. Is it safe to say that they did not actually examinee themselves what is the anthropogenic portion of the warming that has melted glaciers, but, rather, they started with (as a condition/assumption of simulation comparisons) what is thought/assumed/estimated to be the anthropogenic portion of observed warming and then modeled glacial melting to decide how much of the melting was from that portion of the observed warming? They started out with some fixed value/assumption about what part of the general warming is AGW and then looked at melting as a thermodynamics exercise (not a climate exercise, save for precip changes, I guess? It is a seemingly subtle difference not noted in media reports, but is of course different than how some of the headlines read. If the latter, then of course their methods could be 100% correct and yet still not know how much of that melting was actually AGW…since general attribution of AGW was the work of others, eh?
(and my apologies if covered above, I did not read the comments first.)
Over at Bishop Hill, Patagon pointed me at the SI for the paper.
http://m.sciencemag.org/content/suppl/2014/08/13/science.1254702.DC1/Marzeion.SM.pdf
According to the SI, it would appear they’re getting their precipitation/temperature data from the Mitchell & Jones 2005 dataset, which for those who don’t recognise it is the CRU TS2.1 database that ‘Harry’ wrote about in his readme. The original one, that ‘Harry’ was trying to fix.
I find it hard to believe, after Climategate, that anyone would actually use the thing. I mean, you can understand them not wanting to talk about it when that would mean admitting to the problems and having to explain how it happened and why they’re not doing anything about it, but I’d have thought they’d have just let it fade quietly into obscurity.
Interesting.
Nullius, thanks! The BHill excerpts and summary mostly answered my questions. (I guessed wrong about the mechanics of what they did, but think I had the flavor mostly correct about them using existing climate change attribution work.) I’ll have to read closer to see how using a model that attributes most of the recent warming as AGW could conclude recent glacier melting was from any other source but AGW. Could they have expected a different outcome using that model? (I think it is conceivable—considering glacier dynamics like precip, high altitude changes being different from overall changes, or dust—but to this layman the conclusion seems fairly pre-determined by the method.)