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.
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Yet, Dr. Christian Schlüchter discovered that 4,000 years ago, the Swiss Alps were almost glacier free:
http://www.sott.net/article/280759-Receding-Swiss-glaciers-reveal-4000-year-old-forests-Warmists-try-to-suppress-findings
But he didn’t use a computer model, so he must be wrong?
Article is available online at Science Express
Published Online August 14 2014
Science DOI: 10.1126/science.1254702
The final paragraph of their report reads:
“Because the glaciers are considerably out of balance with both mod-eled FULL and NAT climate at the beginning of the simulation period, it is not possible to distinguish between glacier mass losses caused by internal variability and natural forcing. In order to address this question, it would be necessary to identify the causes that led to the buildup of glacier mass during the Little Ice Age, a period not covered by the CMIP5 experiments. However, our results indicate that a considerable fraction of 20th-century glacier mass loss, and therefore also of observed sea-level rise, was independent of anthropogenic climate forcing. At the same time, we find unambiguous evidence of anthropogenic glacier mass loss in recent decades.”
Really what happens, is their model’s outputs work (matches reality in about 1/3) in some places, grossly underestimates Mass Balance loss in some places, and grossly overestimates MB loss in others.
So they decided to disregard those places it fail to match reality, and focus on the places it did as a validation of their model. How’s that for sound science? Answer: Even a blind squirrel finds a nut sometimes. That doesn’t mean the squirrel can see, IMO.
By using computer simulations….
..the planet is now on fire
“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.”
I live near (and climb and ski on) glaciated parts of Canadian Rocky Mountains and if you look at the precipitation and temp records at nearby stations you will find little signal above the noise in the data. How anyone could take that noise and THEN differentiate between natural and anthropogenic changes is fooling themselves.
Here is last 30 years of “climate change” in Banff, Canada, an Environment Canada station close to major glacier icefields:
http://daviditron.files.wordpress.com/2013/05/screen-shot-2013-05-06-at-3-27-05-pm.png
I think I just invalidated their model.
“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,”
They ‘forgot’ to mention worldwide glacier retreat has decelerated since 1950, inconsistent with the above statement.
http://hockeyschtick.blogspot.com/2014/04/new-paper-finds-worldwide-glacier.html … pic.twitter.com/NwkVAxYxcg
And is also based upon climate models previously falsified at 98%+ confidence levels
http://hockeyschtick.blogspot.com/2013/09/ipcc-conveniently-claims-models.html
which use invalid, circular logic to delineate AGW from natural variability
http://www.americanthinker.com/2014/08/climate_science_does_not_support_ipcc_conclusions.html
This belongs in a different thread but I can’t figure out how to start a new one so I leave it to the moderator. Looking at the sea ice page and the Danish graphic of sea ice cover I note that you STILL can’t plot a path from Norway to Alaska where you don’t need and ice-breaker. This while we’re only a couple of weeks away from minimum (maybe less if you look at the mean temperature graph). Anyone remember what year it was we’re supposed to be ice free in the Arctic?
“In our data we find unambiguous evidence of anthropogenic contribution to glacier mass loss.”
Evidence is an observation or experimental result. A computer simulation is not evidence of anything except that they can set up a simulator with a particular paradigm that then runs simulations that are consistent with that paradigm.
(sarc)
Amazing breakthrough!
(/sarc)
“However, during the last two decades between 1991 and 2010 the fraction increased to about two thirds (69+/-24%). ”
So how does one go about detecting which part of a glacier has “natural” melting symptoms and which bits are man made?
What they are clearly doing is projecting attributions _programmed into_ GSMs on the rate of glacial melting. Since those models have failed to get the last 17y of non-warming right, it is pretty clear their attributions are not suitable for derivative work.
No suprise here, as long as we contribute to the warming, we will be contributing to the melting of glaciers as well, which means that this will be faster than if we didn’t. Where’s the news? However, we’re still waiting for someone to demonstrate that melting glaciers are a bad thing.
Nylo says:
August 15, 2014 at 11:00 am
We’re also still waiting for someone to demonstrate that humans contribute to global warming, as opposed to locally as around cities. “We” don’t even know the sign of human contribution to climate change, if any. Humans may have a net cooling effect, but whatever the sign, it’s probably really too small to measure with any precision.
Each time/period in history needs to rethink and revaluated old accepted theories and thesis from new ”days” advancing analyse methods and/or new facts brought to the ”table”. Theories of Science – Basic knowledge
But that’s said it’s empiri not computer models is what it all is about in the end. One need to know about the Earth history and present situation in order to be able to analyse it at all.
Pangea, Earth history essential for world as we know it
Haaaa haaaa. It’s clear now.
William Grubel says:
Anyone remember what year it was we’re supposed to be ice free in the Arctic?
Maybe this will help:
http://www.cnn.com/2008/WORLD/weather/06/27/north.pole.melting/
Joel O’Bryan says:
August 15, 2014 at 10:11 am
“Article is available online at Science Express
Published Online August 14 2014
Science DOI: 10.1126/science.1254702″
———————————————————————————————————————–
Thanks for that. I didn’t need to create a login as the first paragraph set up as a teaser had what I was looking for, to wit:
” Melting glaciers are an icon of anthropogenic climate change.”
Nice to know they went into this modeling with an open mind.
“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”. Key words, if they include solar variability and the volcanic history then they have nothing.
2010, 2011, 2012, 2013, 2014, 2015, 2016, 2019, 2023 and so on.
Hey what, they modelled models in a model? Well that must be all right then (no need for sarc tag I trust?)
milodonharlani says:
August 15, 2014 at 11:03 am
We’re also still waiting for someone to demonstrate that humans contribute to global warming
I personally consider that fully demonstrated already, even though the extent of the contribution is unclear. But even if I didn’t, I would not waste my time arguing whether we do or do not contribute to the warming when the facts are that, be it us or not, we have been warming, and it has been good. Why shouldn’t we want to plead guilty?
Jimbo says:
August 15, 2014 at 11:42 am
— Impressive and timely results. Well done!
It’s always interesting to see how science would operate within an alternate dimension where everything works opposite of how it works in this one. Have a conclusion in mind, then create a computer model to create your conclusion and call it evidence while completely ignoring observations, that’s some good science right there.
“However, during the last two decades between 1991 and 2010 the fraction increased to about two thirds (69+/-24%). ”
///////////////////////
A bit strange since (according to satellite data) there has been no warming for about 17 years 10 months, and the only warming in the 1990s appears to be due to the Super El Nino of 1998, which was not manmade.
Nylo says:
August 15, 2014 at 11:49 am
What makes you believe human contribution to warming has been demonstrated? I haven’t seen any evidence to that effect.
Naturally I agree that so far the world is better off now that it is warmer than during recent centuries, but CACA advocates claim all kinds of terrible things will happen if humans continue contributing to or causing more warming (or climate change), so it matters IMO whether our species is “to blame” or not for some or all of whatever warming has actually been observed since AD 1700, 1850, 1900, 1950, 1977 or whenever.
Dave in Canmore says: August 15, 2014 at 10:31 am
“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.”
Dave is the Columbia Icefield now 2/3 smaller? After-all those Snowcat buses are anthopogenic.
http://jasperjournal.com/journal/wp-content/uploads/2012/08/2012-07-31-IMG_5474-edited-1.jpg
milodonharlani says:
August 15, 2014 at 12:05 pm
What makes you believe human contribution to warming has been demonstrated? I haven’t seen any evidence to that effect.
I’ve seen our CO2 emissions rocket, I’ve seen atmospheric concentration of CO2 rocket, I’ve seen the CO2 absorption bands and I have seen the Earth’s infrared radiation spectrum. I know that more CO2 means slightly narrower radiation spectrum for Earth, which means that, incoming energy being equal, the remaining frecuencies need to carry more energy, and for that to happen, the elements responsible for the emissions in those frequencies have to be warmer. Given that I have seen no evidence of reduced incoming energy and I have seen the world warm, everything adds up.
DD More says:
August 15, 2014 at 12:12 pm
Alaskan glaciers are growing now, not retreating. Look at recent history of Hubbard Glacier, not far from Columbia, for example.
http://en.wikipedia.org/wiki/Hubbard_Glacier
Or temperature history of Juneau, where record high of 90°F was set in 1975. Even in “adjusted” Anchorage figures, hottest year was 1978, despite all the development there since then, & record daily high was in 1953.
http://pafc.arh.noaa.gov/climate/