In our understanding of global geothermal heat flow, Greenland and the surrounding ocean floor has effectively been a blind spot. Now, scientists have dug up all available and somewhat unavailable heat flow data creating common ground for working with Greenland’s geothermal heat as an alternative energy source, a factor in melting of the ice cap, and much more. 

The ground beneath Greenland is colder than previously assumed but the geothermal heat flow seeming to be lower than anticipated does not change the rate at which the ice sheet is melting.

These are two of the conclusions of a paper just published in Earth System Science Data (ESSD) by an international team of scientists led by the Geological Survey of Denmark and Greenland (GEUS). The researchers have compiled a new database and heat flow model consisting of all available geothermal heat flow data for the region. This involved a large amount of digging through ‘grey literature’, or observations not previously included in data-scarce Arctic heat flow models.

The researchers used this observation database to make a new spatial map of heat flow in and around Greenland using machine-learning techniques. The mean heat flow based on 129 new measurements with a total of 419 data points is 44 mW/ m² (milli Watt per square meter), which is substantially lower than what previous models have estimated. “The new database is a significant improvement for this region and a strong new contribution to the Global Heat Flow Database”, says GFZ researcher Sven Fuchs from the Section Geoenergy, who co-authored the new paper and who is maintaining the IHFC Global Heat Flow Database at the GFZ.

Hotpots for geothermal energy  

Even though the mean heat flow across Greenland was colder than previously estimated, the heat flow in coastal areas was in fact much warmer than expected.

“This area along the west coast of Greenland has three times the heat flow as further inland, so it makes sense to investigate the possibility of harvesting the geothermal energy for the communities located there,” says lead author and senior scientist William Colgan from the Department of Glaciology and Climate at GEUS.

A dynamic area

William Colgan describes the research area further: “You have this really old, stable, North Atlantic Craton in the south of Greenland that’s quite cool, and just next to it are the Mid Atlantic Ridge and Iceland with all its volcanic activity. Not to mention the influence of the ice sheet. All of this makes for a geothermally weird region, which is really a bit different from the rest of the world. This area is a geothermal freak zone for sure. And therefore, important to understand.”

The geothermal heat flow seeming to be lower than anticipated does not change the rate at which the ice sheet is melting, Colgan adds. Much of today’s melt reflects the recent warming of the ice-atmosphere and ice-ocean boundaries. The geothermal heat flow at the ice-lithosphere boundary is not changing quickly, but it is important for understanding the stability of the ice sheet at the ice-bed interface.

Compiling a comprehensive overview

Initially, William Colgan and his colleagues became interested in the geothermal heat flow because of its role in the dynamics of the melting ice sheet. Searching for heat flow data from the Greenland area, it quickly became clear that this was a somewhat underdeveloped area. Or at least disorganized: A range of different players collected geothermal heat flow data in and around Greenland through time, but all with individual uses. The oil and gas companies have collected some data to help locate pockets of gas and oil below ground. There’s also the permafrost and glaciology experts who use heat flow as an important boundary condition in their models. William Colgan says: “More or less everybody in geosciences uses heat flow in some sense, but evidently no one has felt the need for compiling a comprehensive overview until now.”

A joint effort: 16 institutions from eight countries

Thus, it turned into an endeavor expanding from the original team of GEUS glaciologists into a range of researchers from different disciplines located in 16 institutions in eight different countries. A joint effort resulted in the new geothermal heat flow model being the first that includes all available offshore and onshore data, including below the ice sheet, in Greenland.

Nevertheless, with 419 data points now registered for the area, the data coverage is still very small for an area as large as Greenland. Greenland has a diversity of geologic provinces and physical processes that contribute to substantial spatial variations in heat flow.

To further increase the resolution, the joint team is currently investigating the possibility of acquiring a heat probe to drop off the back of research vessels going on field work in the Arctic. “This would allow us to continue to fill in the map, which still looks kind of scarce,” the lead author says.

Data and publication

Find the publication ‘Greenland Geothermal Heat Flow Database and Map’ at  https://doi.org/10.5194/essd-2021-290

The in-situ measurement database and gridded heat flow model, as well as other supporting materials, are freely available from the GEUS Dataverse (https://doi.org/10.22008/FK2/F9P03L; Colgan and Wansing, 2021)

Collaborators

• Geological Survey of Denmark and Greenland, Copenhagen, Denmark
• Institute of Geosciences, Kiel University, Kiel, Germany
• Dalhousie University, Halifax, Canada
• Department of Civil Engineering, Technical University of Denmark
• National Space Institute, Technical University of Denmark, Lyngby, Denmark
• DHI Sverige, Stockholm, Sweden
• Cryospheric Sciences Lab, NASA Goddard Space Flight Center, Greenbelt, USA
• Icelandic Geosurvey, Reykjavik, Iceland
• Faculty of Built Environment, Tampere University, Tampere, Finland
• Helmholtz Centre Potsdam, German Research Centre for Geosciences, Potsdam, Germany
• Swedish Nuclear Fuel and Waste Management Company, Stockholm, Sweden
• Center for Earth Observation Science, University of Manitoba, Winnipeg, Canada
• Department of Geography, University of Copenhagen, Copenhagen, Denmark
• Planetary and Magnetospheres Laboratory, NASA Goddard Space Flight Center, Greenbelt, USA
• Department of Geoscience, Aarhus University, Aarhus, Denmark
• Asiaq – Greenland Survey, Nuuk, Greenland

Scientific contact:

William Colgan (GEUS)
Department of Glaciology and Climate
Geological Survey of Denmark and Greenland (GEUS)
Email: wic@geus.dk
Telephone: +45 9133 3814
 

Agnes Wansing (CAU)
Institut für Geowissenschaften
Christian-Albrechts-Universität zu Kiel (CAU)
Email: agnes.wansing@ifg.uni-kiel.de
Telephone: +49 176 45724022

Sven Fuchs
Helmholtz Zentrum Potsdam
Email: fuchs@gfz-potsdam.de
Telephone: +49 331 2881713

Media contact:

Johanne Uhrenholt Kusnitzoff
Geological Survey of Denmark and Greenland (GEUS)
Email: jku@geus.dk

Tobias Hahn
Kiel Marine Science (KMS)
Christian-Albrechts-Universität zu Kiel (CAU)
Email: thahn@kms.uni-kiel.de

Josef Zens
Leiter Presse- und Öffentlichkeitsarbeit
Helmholtz-Zentrum Potsdam
Deutsches GeoForschungsZentrum GFZ
Telegrafenberg
14473 Potsdam
Tel.: +49 331 288-1040
E-Mail: josef.zens@gfz-potsdam.de