Documentary film brings you along when scientists melt holes in the Greenland Ice Sheet

Published 09-03-2023

In a new documentary, you can see researchers testing whether a very hot metal rod can provide unique insight into the bottom of the Greenland Ice Sheet and ultimately improve our ability to predict sea-level rise.

An assembled HotRod version 3 on a frozen lake near Thule Air Base (Pituffik) in north-eastern Greenland. The melting tip is approximately two metres long, weighs 10 kg and is powered by 6000-volt heating cartridges. (Photo: GEUS)

Director Anders Graver followed two researchers as they tested a newly developed electric melt-tip drill called HotRod for the first time in 2022. This turned into the documentary film ‘The Color of Ice’, which premieres at the documentary film festival CPH:DOX this year.

In the documentary, you follow, among others, Senior Researcher William Colgan and Engineer Christopher Shields, both from the Geological Survey of Denmark and Greenland (GEUS), as they test the electromechanical melt-tip drill and find out whether the many years of development work and laboratory tests will pay off.

Join the scientists in their tent when they fail

"Part of research is that we try things out and learn from our mistakes. That is fundamental to research," says Christopher Shields.

And this is proven in the documentary, as the melt-tip drill overheats during the first test. This is just another step on the way to the bottom – the bottom of the Greenland Ice Sheet that is! The test was designed primarily to test the support instruments, so William Colgan and Christopher Shields just made do with an old version of the electric fusion drill. When they used a new drill a few days later, they reached the rock under the ice in just one day.

A hunter named Olennguaq Kristensen also participates in the film and the viewer witnesses how both the hunter and the two researchers have to deal with the ice, which creates the practical framework for their work. For one of them, the Greenland Ice Sheet is his livelihood, for the other two, the ice sheet is the primary object of their trip. What they have in common is their attempt to understand the ice, and they experience it changing over time.

Foto: William Colgan holds the approximately two-metre-long melt-tip drill in front of a tent on the Greenland Ice Sheet. (Photo: Underground Channel, Humbug Film)

Melting the ice to understand the melting of the ice

By now, we’re used to hearing about IT security professionals hacking into programmes to identify and close holes that cybercriminals can use. But melting holes in the Greenland Ice Sheet to learn about the melting of the ice – that is a bit more challenging for one’s logical sense.

But there is a certain logic in William Colgan’s arguments when he explains what the HotRod project is all about. Because what is the fastest and most efficient way to get through a 500-meter-thick layer of ice?

"You melt your way with a very hot metal rod," says William Colgan.

Hence the research project’s rather special name: HotRod. Well, naming research projects doesn’t have to be rocket science. But since it seems logical to melt through the ice, one might wonder what is so special about the HotRod project.

Several months’ worth of work in a week

The whole point of going through the Greenland Ice Sheet is to measure the temperatures down at the ice-sheet bed. This is because the temperatures there can be used in models that show the melting of the Greenland Ice Sheet, and these models can give us information about sea-level rise. Temperature is an important parameter to control in the models because ice at 0 degrees Celsius deforms ten times faster than ice at 10 degrees Celsius.

In recent decades, traditional measurements of temperatures under the surface of the Greenland Ice Sheet have typically been done by drilling through the ice with electromechanical drills. This work requires a lot of people, a lot of time and a lot of resources: thousands of litres of petrol, electricity, food for all the participants and much more.

"The depths that it normally takes several months and large amounts of resources to reach with electromechanical drills, could be reached in a week with an electric melt-tip drill and with the efforts of only two people and two pallets of equipment," says Christopher Shields, Engineer and Technician at GEUS.

In the past, melt-tip drills have also been used in the exploration of the Greenland Ice Sheet, but they are not as easy, stable and accessible as electromechanical drills, which have therefore been the preferred tool. But William Colgan believes that the technological development has now reached a point where it is time to give the melt-tip drill another chance.

Hopefully, an efficient electric melt-tip drill can make the exploration of the deep ice cheaper, faster and more resource-friendly.

Foto: William Colgan, Senior Researcher, and Christopher Shields, Engineer, looking at the HotRod drill in the workshop at GEUS (Photo: Underground Channel, Humbug Film)

Black holes in our knowledge about ice

The deep ice consists of ice from the Pleistocene, which is the geological term for a period that extended from 2.6 million years ago to approximately 17,500 years ago. The ice above that is from the Holocene, which lasted from approximately 17,500 years ago till now. The two types of ice behave differently, and we know very little about the temperature at the bottom because it is so demanding to get down there.

"If we want to know more precisely how much the ice melts, and how, we need to know more about the deep ice. What we know now is that it deforms about three times as fast as the ice from the Holocene, but the temperature also affects how fast the ice melts. Therefore, we need to know how much of this kind of ice there is, where it is, and what the temperature at the bottom is, so that we can make accurate models of when and how much the sea rises," says William Colgan.

In other words, we have to drill boreholes in the ice to cover the gaps in our knowledge about the melting of the Greenland Ice Sheet. If an efficient melt-tip drill can make the acquisition of new data cheaper and easier, we can speed up the knowledge acquisition we need to be able to prioritise efforts for climate adaptation.

Since 2012, Greenland has lost approximately 225 gigatons of ice per year. For every gigaton of ice melting, oceans worldwide rise approximately 0.0028 millimetres. This means that melting from the Greenland Ice Sheet has caused the world’s oceans to rise by approximately 6.3 millimetres since 2012.

Read more about melting and mass balance on

Melted ice causes more water at the equator

And now it’s time to hold on to your hat and reading glasses, because your logical sense may be challenged once again. You might think that when the Greenland Ice Sheet melts, the sea around Greenland rises. But it doesn't. On the contrary, the sea level around Greenland falls when the ice melts.

"When the ice melts, Greenland loses mass, and thus Greenland becomes lighter and is even lifted a little, and its gravity becomes weaker. Therefore, the water moves towards the equator, where the force of gravity does not change,” William Colgan explains.

The melting of the Greenland Ice Sheet can therefore cause floods, especially around the equator, as the water level rises. This makes climate research on the Greenland Ice Sheet an area of great international attention.

HotRod ready for work on the Greenland Ice Sheet

William Colgan and Christopher Shields consider the test of the electromechanical melt-tip drill a success. During the test in May 2022, they reached a maximum drilling speed of 4.5 metres per hour. Now they are attempting to improve the system so that they can reach 20 metres per hour.

"Until now, the HotRod project has focused on developing the technology. Now we want to implement the technology in our scientific work with data collection,” William Colgan says.

William Colgan received 2 million DKK from VILLUM FONDEN for ’HotRod: Prototype for Rapid Sampling of Ice-Sheet Basal Temperatures’ i 2018.

Trailer: The Color of Ice

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About the film

The documentary film ‘The Color of Ice’ is produced by Underground Channel at the Natural History Museum of Denmark, University of Copenhagen, and Humbug Film. The film is financed by Geocenter Danmark and VILLUM FONDEN.

The film is produced by Anders Drud. It has been selected for screening at the CPH:DOX documentary film festival in 2023.

The film has also been selected for UNG:DOX. This means it will be shown to high school students, and William Colgan and Christopher Shields will meet the students and discuss their work.

William Colgan
Senior Researcher
Glaciology and Climate
Christopher Shields
Engineer, technician
Glaciology and Climate
Malene David Jensen-Juul
Communications Officer
Press and Communication