From the Helmholtz Association Greenland ice is melting — also from below
Heat flow from the mantle contributes to the ice melt
The Greenland ice sheet is melting from below, caused by a high heat flow from the mantle into the lithosphere. This influence is very variable spatially and has its origin in an exceptionally thin lithosphere. Consequently, there is an increased heat flow from the mantle and a complex interplay between this geothermal heating and the Greenland ice sheet. The international research initiative IceGeoHeat led by the GFZ German Research Centre for Geosciences establishes in the current online issue of Nature Geoscience (Vol 6, August 11, 2013) that this effect cannot be neglected when modeling the ice sheet as part of a climate study.
The continental ice sheets play a central role in climate. Interactions and feedback processes between ice and temperature rise are complex and still a current research topic. The Greenland ice sheet loses about 227 gigatonnes of ice per year and contributes about 0.7 millimeters to the currently observed mean sea level change of about 3 mm per year. Existing model calculations, however, were based on a consideration of the ice cap and considered the effect of the lithosphere, i.e. the earth’s crust and upper mantle, too simplistic and primarily mechanical: the ice presses the crust down due to its weight. GFZ scientists Alexey Petrunin and Irina Rogozhina have now coupled an ice/climate model with a thermo-mechanical model for the Greenland lithosphere. “We have run the model over a simulated period of three million years, and taken into account measurements from ice cores and independent magnetic and seismic data”, says Petrunin. “Our model calculations are in good agreement with the measurements. Both the thickness of the ice sheet as well as the temperature at its base are depicted very accurately. ”
The model can even explain the difference in temperature measured at two adjacent drill holes: the thickness of the Greenland lithosphere and thus the geothermal heat flow varies greatly in narrow confines.
What does this mean for climate modeling? “The temperature at the base of the ice, and therefore the current dynamics of the Greenland ice sheet is the result of the interaction between the heat flow from the earth’s interior and the temperature changes associated with glacial cycles,” explains corresponding author Irina Rogozhina (GFZ) who initiated IceGeoHeat. “We found areas where the ice melts at the base next to other areas where the base is extremely cold.”
The current climate is influenced by processes that go far back into the history of Earth: the Greenland lithosphere is 2.8 to 1.7 billion years old and is only about 70 to 80 kilometers thick under Central Greenland. It remains to be explored why it is so exceptionally thin. It turns out, however, that the coupling of models of ice dynamics with thermo-mechanical models of the solid earth allows a more accurate view of the processes that are melting the Greenland ice.
Petrunin, A. G., Rogozhina, I., Vaughan, A. P. M., Kukkonen, I. T., Kaban, M. K., Koulakov, I. & Thomas, M., “Heat flux variations beneath central Greenland’s ice due to anomalously thin lithosphere”, Advance Online Publication, Nature Geoscience, 11. 08. 2013, http://dx.doi.org/10.1038/ngeo1898)
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No you didn’t – you found numbers in your model that you are interpreting to meant this – but you haven’t actually “found” anything physical at all.
(wow – previews too!)
Now that’s the Global Warming I’m talking about!
steveta_uk says:
August 12, 2013 at 9:09 am
Yes.
Moreover, approaching the variables that nobody wants to acknowledge through the back door of modelling is just cheap. Let’s face it, the climate change community is so vested in the single-variable system (CO2) that it will never make the effort to see how much they need to learn about geodynamics.
I expect they’ll blame it on global warming anyway!
So how do they blame CO2 for the heating of the mantle?
“The current climate is influenced by processes that go far back into the history of Earth:”
Yet the word ‘anthropogenic’ has maximum credence for current climate changes.
I wonder if it is possible to “see” under the ice and look for lava flows and spent volcanoes. I am guessing it is not possible to drill 70 km and look at a core of the underlying lithosphere?
Interesting article but “Our model calculations are in good agreement with the measurements.” is the same mealy mouthed “Corporate News Release” that inspires me to wonder what the agenda of the info is. I have no clue here though…
The GFZ illustration as I read it shows that the warmer [temperature] is near the surface. That seems contrary to what the article is saying. Having been deep underground in a Colorado gold mine I know that was very hot compared to the surface. To me this article is puzzling in terms of it actual surface level effects in the short term.
Read… “warmer temperature” …
Not surprising, considering that the core of the earth is hotter than the sun….on the Tonight Show, hosted by Conan O’Brien, the Goreacle sayeth:
There is nothing new or surprising about this finding. I recall being in Whitehorse in the Yukon back in the 1960s when glaciologists flew in from all over the world because the Donjek glacier began surging. These are generally called “galloping glaciers”. Most often the action is attributed to increased basal slip as a layer of water forms between the ice and the bedrock, usually caused by geothermal heating.
One reason this issue is avoided is because it speaks to the issue of geothermal heating as a source of energy for the global system, especially under the oceans where the crust is thinnest. This is exacerbated by the crustal warping and deformation caused by the weight of the glacier.
From ‘Denmark’ thread:
vukcevic says:
August 11, 2013 at 3:46 pm
Iceland and the Arctic are unique, there continental plates are spreading out. Magma pouring out to the surface is directly from the Mantle’s convection cell (thermal circulation all the way from outer core- liquid iron & nickel to the Earth’s surface).
In most of other volcanic areas magma is product of tectonic plates subduction process, with no direct link with convection cells.
http://www.vukcevic.talktalk.net/Ap-VI.htm
first posted on WUWT one year ago, almost to a day.
Leif Svalgaard says:
August 11, 2013 at 4:26 pm
So what, the plates are spreading all along the mid Atlantic ridge.
This finding is irrelevant when it comes to future climatic change ,which is going to be downwards in temp. due to the prolonged solar minimum .
This conclusively proves that it is All George Bush’s Fault.
“the warmer tee rapture” – I know what your typo intended, but I’d much rather let the modelers figure out the proper parameterization to get tee rapture right.
1.August 8, 2013 at 12:51 pm
2.
Leif Svalgaard, is in a dream world when it comes to what is currently taken place on the sun and the future climatic implications.
3.
Leif has no regard for past history which lends support that the sun is much more variable then what he keeps trying to convey and that the solar conditions during the MAUNDER MINIMUM were very weak(aa index near 0 ,solar wind 200km/sec) and how this correlated to the very cold conditions at that time. In addition he keeps trying to down play the significance of how very very weak solar cycle 24 is and will be going forward.
4.
This flip is nothing like a normal flip and I would not be surprised (as the prolonged solar minimum continues due to angular momentum exerted by the planets on the sun, which Leif also says is not correct) that this may be the last flip , or at the very least the future flips are going to be even less pronounced then even this one.
5.
Leif, and the mainstream keep trying to play up the fact that the sun is acting the same now as it has all of last century which can not be further from the truth.
6.
This cycle could be weaker then solar cycle 5, and is much weaker then solar cycle 14 . Layman sunspot counts and graphs which are correct show this clearly to be the case.
7.
The AP index and solar flux going forward will end this debate, and as of today we have solar flux around 105 at the maximum ! It should be north of 150.
8.
Also since Oct 2005 the AP index has been extremely low and I expect sub 5 will be the rule in the not to distant future, at least post 2015.
9.
Once the solar parameters hit the levels I have been saying (see below) I list the potential secondary effects which could take place as a result.
10.
1. solar flux sub 90 but better sub 72, less UV light less ozone more meridional atm. circulation ,more clouds,snow cover and precip.,higher albedo ,colder temp. N.H.
11.
2. precipitation patterns changing can impact the thermohaline circulation perhaps slowing it down if precip increases substancially and adds more fresh water to the system.
12.
3. solar wind sub 350 km/sec but better sub 300 km/sec, more cosmic rays more clouds ,higher albedo, colder temp. more geological activity especially in high latitudes.the geo magnetic field weakening of earth promoting this even more.
13.
4. solar irradiance off .015% less visible light ocean heat content subsides
14.
5. ap index 5 or lower with isolated spikes will cause the plates to be more unstable, more volcanic activity and earthquake activity. more shocks to the magnetosphere.
15.
6. low solar in addition to being correlated with an increase in major volcanic activity and earthquakes in and around the solar minimums also can be tied to a cold pdo/amo. a cold pdo translates to more la ninas versus el ninos the result global cooling.
16.
7. low solar activity having severe impacts to the Thermosphere and Ionopsphere.
Thermosphere will contract and cool substancially during a prolonged solar minimum which will inter act with all the other layers of the atmosphere.
17.
This explanation is the ONLY explanation that can explain the many past abrupt climatic changes of the past both up and down. There are no other explanations from Milankovitch Cycles, to the Thermohaline circulation shutting down, to extra terrestrial impacts,to the sudden increases in greenhouse gases like methane or co2 etc etc.
18.
The explanation above shows how the climate could be brought to thresholds if the solar parameters change in degree of magnitude strong enough and for a period of duration long enough following a sufficient number of years of sub- solar activity in general, which no other explanation is able to show.
19.
Thresholds have to be met to flip the climate from one climatic regime to another. When the climate is in the same climatic regime changes are gradual and slow and always stay within particular boundaries.
20.
I am still waiting for alternative explanations, have yet to see one.
21.
22.
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No matter how valid the underlying geophysics, there is no way these models are validated or say anything about melting and sea level. The image shows that the hottest modeled ice is still -2C. Melt? And the image shows two basal ice sheet data points, GRIP and GISP2. Although two points suffice for a trend line, it takes a minimum of three to begin to validate that line.
At least the study is better than most climate science, which seems to use only one datapoint and a theory to anchor projections. Unless it is Trenberth’s missing heat, in which case theory alone sufficed.
There’s an inherent hazard in trusting or distrusting “models” that is often ignored in all the sciences. Looking at the preview there are several important facts that help determine the reliability of the results and are important. The chief one is how the “Curie point” or transition point depth is estimated. It is estimated from data collected by measuring regional magnetic field strength. Since hotter materials will have weaker magnet field strengths, and will lose magnetic field below the transition, you can estimate depth below surface of the transition point if you have a good idea of the mineralogy involved, since a cold hunk of the rock can retain a magnetic field of a strength limited by the mineralogy of the rock. If you have the mineralogy, you can also provide a good estimate of thermal conductivity in the regional crust.
Depth of transition point, related to base of ice sheet gives a thickness of the lithosphere and geothermal heat flow can be modeled from the two surfaces. The estimated Curie point depths in the region provides one surface and the sounding of the ice sheet provide the other. That is far more straightforward than “feed backs” and “forcings.”
The essential conclusion of the article is that current climate models dealing with the ice sheets are too simple, which sceptics have been arguing all along.
Dear Sir,
There is considerable excitement among the Green activists because it seems that the Greenland Ice Sheet is melting. This, they claim, is proof positive that we are now seeing the results of Global Warming due to man. However, in the year 982 AD a rather turbulent Viking Erik the Red sailed west and found a green land which he called ‘Greenland’. He then began to colonise Greenland. It was then green with grass and virtually no ice. Over next four or five hundred years the colony built up to over 4000 – 5000 people with over 150 farms and was more or less self sustaining. The ice returned at the beginning of the Little Ice Age and the colony then failed. During this period there were no factories, central heating or other significant sources of man made CO2. Why the fuss and claim that the current loss of ice in the northern hemisphere (but not in the Antarctic) is due to man? Mick G
________________________________
Are you saying “virtually no ice” anywhere in Greenland, or only along the southeastern coastline where the to settlements were established, as I has always understood the case to be?
“This conclusively proves that it is All George Bush’s Fault.”
George Bush’s Fault. Is that some place where the Pacific and North American plates collide?
It’s worse than we thought!
Below is Co2 Science’s comment and quotes from the full paper I presume.
Salvatore Del Prete (10:01 am) exactly what has this extended whinge about your dislike of Dr. Svalgaard got to do with geothermal modelling?
http://youtu.be/f1ztg0wUqKY
It looks like that they can live together.
Doubt the models, as usual but there’s high probability that we’ll see a “study” soon claiming the warming of the underlying rock is somehow influenced by CO2.
steveta_uk says:
August 12, 2013 at 10:34 am
Salvatore Del Prete (10:01 am) exactly what has this extended whinge about your dislike of Dr. Svalgaard got to do with geothermal modelling?
Pseudo-scientists, alarmists, and agenda-driven people will use every forum they can to peddle their nonsense [on topic or not]; there has already been a couple of comments of this ilk on this very thread – expect more.