Heat flow from Earth's mantle contributes to Greenland ice melting

Greenland ice is melting -- also from below
Modeled basal ice temperatures of the present-day Greenland Ice Shield across the Summit region, GRIP and GISP2 indicate borehole locations. Credit: A. Petrunin/GFZ

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 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 of about 3 mm per year. Existing , however, were based on a consideration of the ice cap and considered the effect of the lithosphere, i.e. the earth's crust and , 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 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.

Explore further

Enhanced melting of Northern Greenland in a warm climate

More information: 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, Aug 11 2013, dx.doi.org/10.1038/ngeo1898
Journal information: Nature Geoscience

Citation: Heat flow from Earth's mantle contributes to Greenland ice melting (2013, August 11) retrieved 18 August 2019 from https://phys.org/news/2013-08-earth-mantle-contributes-greenland-ice.html
This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.

Feedback to editors

User comments

Aug 11, 2013
Fact check: "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."

Tide gauge data extends back from present 150 years instead of only 20 for satellites and suffers no serious calibration controversy (see: laugh test), and that data shows half of this claimed rate of rise.

Also, the overall ice mass loss from Greenland is exactly 50% compensated for by Antarctic ice mass gains, according to the IceSAT satellite.

Another region in which a hot rocks melt ice is where the dense loop of volcanic hot spots extends along the whole west coast of S. America down along the peninsula of Antarctica, where all the Global Warming claims originate from.

The central problem with modeling climate is that overall heat dynamics is dominated by ocean cycles that come and go chaotically due to fluid dynamics, above a moody mantle.

Aug 11, 2013
an article about the ice shelf breakup ---Larsen B----explains that sudden release of water lakes that had previously sat on top of compressed ice sheets , occurs when the water leaks through the ice shelf in giant cracks to the bottom. the release of pressure upon the top of the ice sheet allows more cracks to form as there is a sudden release of compression---the ice shelf adjacent to the previously existing 'lake' then becomes weakened and cracked.

perhaps the earth itself , as it lifts up isostatically can develop crack or depressurized areas where buckling and mixing can occur---creating a karst like terrain for water to then enter [ especially if there is limestone in the area----

even without cracks and fissures being filled with water, its possible a sudden release of pressure on the earth could encourage the upwelling of heat from below in an area where beofre there was a stable high compression load of ice above the earth, itself above deep earth.

Aug 11, 2013
This comment has been removed by a moderator.

Aug 11, 2013
an article about the ice shelf breakup ---Larsen B....

Map of where Larsen B ice shelf existed in Antarctica, along with red dots indicating volcanoes:


Aug 13, 2013
Larsen B is not applicable. It was an ice sheet, and not glacial.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more