Ice melt and motion measurements on south Greenland glaciers

Last year, FORLOH funded the installation of climate monitoring equipment in Greenland. Together with Greenland Guidance, ice melt and motion trackers were placed at three distinctly different glacier sites in south Greenland. Now, after having collected more than a year’s worth of data, the region is starting to reveal its characteristics. Comparing these new measurements to those taken 40 years ago tells us something about the impact of climate change.

See the original blog post on the FORLOH website.

Why doing science in Greenland is important

Greenland is located in the far north where temperatures are increasing faster than anywhere else on our planet. The world’s largest island is of particular interest because of its enormous, three kilometer thick ice sheet. If melted, the ice sheet would raise global sea levels by nearly three floors of a building, causing trillions of dollars worth of trouble for coastal areas across the globe. As mentioned in a previous blog post, the warmer it gets, the more the ice sheet mass loss becomes an unstoppable, runaway process. And this is just one of the facets of climate change. Scientists warn politicians that we are heading towards a brick wall and should push the brakes instead of easing off the throttle.

Reason enough to assess the state of the Greenland ice sheet by taking detailed measurements. That’s why FORLOH started investing in climate science in 2021. We selected the southern part of the Greenland ice sheet as our study area. Here, because conditions down south are a bit warmer, we can see how the rest of the ice sheet will fare in a future warmer climate.

Google map showing the locations of the FORLOH-sponsored glacier monitoring sites in Greenland. Zoom in to take a closer look.

Rugged instruments in extreme climate conditions

Last year, towards the end of the short Greenland summer, we installed three custom-built draw wire ice ablation trackers (DWIATs). Such instruments are used to study the two most important mass loss processes for the Greenland ice sheet: how fast the ice melts, and how fast the ice flows to the sea. Anything installed on an ice sheet, or on glaciers, moves with the ice as it melts downward when temperatures are above-freezing, and as it slowly flows downslope. This “moving with the glacier” is precisely what we take advantage of in our monitoring techniques.

We chose three sites with very different characteristics to be able to study the whole range of climate impacts. Site 1 is on a slow-moving part of the main ice sheet, right next to a moulin – a meltwater drainage hole running straight through the ice sheet. Site 2 is on the fast-flowing valley glacier, named Eqalorutsit Kangilliit Sermiat; this glacier ends in a fjord where it produces icebergs, making it dynamically a different glacier than land-terminating ones. Site 3 is on a much slower, lake-terminating glacier named Nordbogletsjer, and provides historical context as the site was also monitored four decades ago.

A draw wire ice ablation tracker, measuring glacier melt and motion. A wire running down from the instrument box is drilled into the glacier; as the ice surface melts down, the wire coils up in the box, so that the onboard computer can record how much ice has melted.

One thing these three sites have in common is that climate conditions are tough. Temperatures drop far below freezing in winter. Storms are among the fiercest on the planet. Drifting snow in winter bombards the instruments with static electricity. And a thick layer of winter snow exerts huge pressure on anything buried in it, as it compresses and melts in spring. That’s why we use extremely rugged instruments that are custom-built to survive anything the polar climate can throw at them.

Because the instruments also transmit their measurements via satellite link, we can study their data even before returning to the sites for maintenance. So let’s have a look at what the ice sheet has been up to over the past year.

Slides and caterpillars

The instruments measure ice motion using GPS. The glaciers flow from high to low elevations year-round, as gravity urges the ice down to the fjords. After more than a year of measuring, we now have a good idea of the average velocity at the three measurement spots. At “slow” site 1, the ice moves with an average velocity of 49 meters per year. At site 2, much more ice is transported judging from the average velocity of 1113 meters per year, over 20 times faster. The ice at site 3 moves 97 meters per year.

The horizontal velocity at which the ice moves at the three measurement sites. Note the difference in scales between sites 1 and 3 (left axis), and site 2 (right axis).

Big dynamic differences between the sites can also be seen in the annual cycles. The above graph shows that the ice at site 2, and to a lesser extent at site 3, has increasing velocities between autumn and spring – the period without significant melting. This has to do with mass building up as ice is constantly being supplied from higher regions of the ice sheet. Then, at the start of the melt season (in May), the ice suddenly accelerates. This occurs when meltwater runs straight down through cracks in the ice, making the glacier bed wet and slippery, causing the glaciers to slide more quickly. Once the glaciers have adapted to this by creating subglacial channels, efficiently draining the meltwater to the fjord, they regain their footing and the velocity drops during summer – in spite of large amounts of meltwater running through the system!

Site 1 does not experience a clear seasonality in ice velocity, indicating that the ice “conveyor belt” works differently here. Instead, a clear (roughly) three-week periodicity in speed exists at site 1, which can also be identified at both other sites. Velocity peaks at the three sites often occur at the same time, in spite of the tens of kilometers/miles separating them. This type of variability is often due to weather, with rain or melt events presenting the glacier bed with more water than it can handle, causing enhanced sliding and motion for a few days. But this is not all. The ice sheet has also been shown to move like a caterpillar, with velocity “waves” moving through the system. This can also explain part of the variability seen in the velocity graph.

The change in altitude of the three instruments since their installation in 2021.

To add to the picture, the above graph shows the change in instrument altitude. Fast site 2 is seemingly the most straightforward to interpret; here the ice flowed downhill by over a kilometer, losing 46 m of elevation in the process. But the other two sites show a more complicated story. During winter they actually gain altitude, as ice is supplied from higher regions, piling up the ice in its path. This local mass gain is then compensated during summer, when melting happens. At site 1, the two processes of ice dynamics and melting combined resulted in net thinning of the ice sheet by up to two meters in the past year, which fits the trend of what is seen around the ice sheet in the current climate. But remarkably, at site 3 we see a net thickening of about two meters. This is likely because more ice is flowing into the area than before due to an acceleration of the glacier on which site 2 is located, which feeds Nordbo glacier of site 3. As we’ll see below, it’s not because the ice is melting less these years.

Ice melt larger than 40 years ago

The instruments keep track of ice melt by measuring the length of a draw wire drilled into the ice. When the ice melts, the instrument tripod melts down with it and the wire coils up in the sensor. Even though a lot of snow falls in winter, and melts again in spring, this doesn’t contribute to the net surface mass balance – the mass lost over a year. The melting of the bare ice underneath started in June. With the melt season having come to an end in early October, we can assess that at the first site 3.98 meters (1.5 floors) of ice melted, at the second site 2.37 meters, and at the third 2.75 meters. The fact that site 1 melts fastest is partially due to it being at lower elevation where conditions are warmer (670 meters above sea level, versus about 800 and 880 meters at sites 2 and 3).

The amount of ice melted in 2022 at the three sites.

Up to four meters is a lot of ice, but it is impossible to know whether this is a “big” or “small” melt year without comparing it to other years. Not coincidentally site 3 was chosen for instrumentation. Here, researcher Poul Clement measured the surface mass balance on behalf of the Geological Survey of Greenland between 1977 and 1983. Various old data reports tell us that in 2022 melt at site 3 was about 24% larger than the average for 1977-1983. Even though 2022 was not a particularly warm year in the current climate. So a melt year that is “average” at best in present-day climate conditions, still exhibits considerably more melt than 40 years ago when “normal” was cooler.

The complexity of it all

The below graph shows how it all fits together at site 3; ice velocity, thickness and melt all interact. You’ll see two things that you couldn’t tell clearly from the previous graphs. The first is that the altitude drop that starts in early summer is largely due to melting. This makes sense: ice flow transports the ice into the area, and melting removes an approximately equal amount of mass. If it didn’t, the system wouldn’t be in balance, generally speaking.

The data collected at site 3 combined in a single graph. Note the different Y-axis for the yellow lines on the right-hand side.

The second thing to notice about the graph is that the high-frequent changes in ice velocity and thickness correlate pretty well. But ice thickness seems to be leading on most occasions: first the ice thickens/thins, and then, as a result, the ice starts moving faster/slower.

In hard-to-reach places, collaboration is key

We think it is imperative that scientific data are collected for the good of everyone. That’s why our data is open-access, available to anyone across the globe. You are more than welcome to have a look at the data here. If you’re a scientist (or student or teacher or just someone with an interest in glacier data), we can send you a batch of raw or processed data for you to use in your research. We’ll also upload the data to the servers of the Programme for Monitoring of the Greenland Ice Sheet (PROMICE) where scientists can download all sorts of important glaciological data and use them for generations to come.

The open-access nature of science becomes even more relevant in remote places, where transportation (by helicopter) is expensive and opportunities for visiting hard-to-reach field sites are few. Therefore we are excited that the large Swiss Green Fjord project chose the same region to study, resulting in data exchange and logistical collaboration. Likewise, the Geological Survey of Denmark and Greenland, already active in the region for decades, chose FORLOH site 2 to install a phase-sensitive radio echo sounder – a radar system for studying processes at the glacier bedrock, putting our data to good use.

Looking forward

So the data have given us some first insights into the workings of the ice sheet and the interaction with the climate. Data is flowing towards climate scientists and whoever else shares the passion. This will help with better interpretation of satellite imagery in ice sheet studies, and with more precise computer models predicting the future state of the ice sheet. The more measurements we take, the more we contribute to climate science, especially in a remote and special place like Greenland. Because only few such measurements exist.

But perhaps the most relevant will be to see how ice melt and motion will change in the coming years, to get a good understanding of interannual variability, and to keep a finger on the pulse of the shrinking ice sheet. It won’t be long before we’ll be able to use simple computer modeling to estimate future melt in different atmospheric warming scenarios. Then we’ll know better how much this large ice-covered region can contribute to sea level rise. And as a scientific community we’ll have more evidence to share with policy makers, so that they can take action to further combat climate change.

Why the spring peak in Greenland field activities?

Field activities in Greenland are often confined to spring and summer. In autumn and winter, low temperatures, snowfall, the lack of sunlight, and more frequent storms do not provide optimal working conditions. Besides, the most interesting processes to study primarily occur in the warm season, such as the melting of the glaciers and ice sheet.

There are two distinct peaks in Greenland field activities. The first is in spring, for those people who need to get out there when things are still frozen, but when daylight and weather conditions are workable. The second peak is in mid-to-late summer, when weather conditions are best, melting is strongest, and the ice sheet margin and tundra is snow-free and more accessible. In between there is a potentially less pleasant period with often soggy conditions, and billions of mosquitoes. With the summer peak getting underway, let’s see what the spring rush is all about.

Installing instruments before the warm season

A good reason to get over to Greenland in spring is when you want your instruments in place to monitor what’s happening during the “warm” season, when plants grow, animals reproduce, and glaciers melt. Or, in the case of the University of Fribourg, when meltwater is generated at the top of the snowpack on the ice sheet. The Swiss scientists have now returned several times to the same sites in the lower accumulation area. They study how much meltwater gets refrozen in the cold snow underneath the surface, how much runs off into the ocean, and how this will change in time. Greenland Guidance provided weather forecasts for them to optimize their activities and prepare camp for storms, if needed. This spring their field team had two weeks on ice with surprisingly good weather conditions.

The University of Liverpool placing a weather station next to a fast-moving glacier (photo: James Lea).

Another team out there this spring was the University of Liverpool, who where installing GG-built instruments at a fast-flowing glacier in southwest Greenland. They are investigating a glacier that has retreated a lot in the past few years. When such a glacier experiences melt, an already complex system becomes even more complicated, for instance because of large pulses of meltwater originating from ice-dammed lakes along the sides. Or from rain events. With their instruments up and running in mid-May, they timed it well.

In May and June, the Geological Survey of Denmark and Greenland (GEUS) visited GC-Net weather stations high on the ice sheet. This is part of their annual maintenance efforts that take place in spring to make sure all systems are up and running during summer. We were invited along to help out. Each station takes several hours to service, but the more people can help, the faster the Twin Otter airplane can return to town. The machine experienced engine trouble, but luckily this happened at the airport before departure, and not on or over the ice sheet.

Preparing for takeoff to do maintenance at GEUS GC-Net sites (photo: Ken Mankoff).

Snow conditions

A second reason for the GC-Net maintenance to take place when it is a bit colder has to do with snow conditions. The scientists need to dig deep snow pits to asses the mass of the snow that fell since the last site visit, and this is done best before seasonal melting happens.

For others a cold snow layer means increased safety. Ski traversers crossing the ice sheet have to pass crevasse fields, and this is done much more safely if there is a solid snow bridge on top, deposited during winter. When snow gets wet because of melting, such bridges get weaker, and falling through them into a deep crevasse becomes a serious threat. That’s why the wind-powered kite-ski traverse team led by Bernice Notenboom did their expedition before the melt season, in May. They traveled an astonishing distance of nearly 2000 km from ice sheet base Dye-2 to the northwestern town of Qaanaaq. During their expedition they were confronted with several storms that we warned them about via satellite transmission.

The Winds of Change kite-ski camp

Preparations for summer

Often spring activities are mere preparations for summer expeditions. Take for instance the greenhouse in Narsaq in south Greenland. In order for charitable organization Greenland Trees to be able to plant trees along south Greenland fjords at the end of summer, their new greenhouse had to be prepared for growing seeds and cuttings in April and May. It took a lot of effort, but is was truly nice to notice how happy locals are with the project, and how eager they are to collaborate – including schools.

The Greenland Trees greenhouse in Narsaq.

In terms of volume, most of our clients and collaborators are scientists or camera crews, asking where to rent a boat, how to get permits, which locals to interview, and how to get to a remote site. But we also provided support to Swedish company SKB, who have been running and funding science projects in the Kangerlussuaq region over the past 15 years. In preparation of a groundwater sampling campaign to occur at their unique bedrock borehole in late summer, we went ahead and inspected the state of their equipment, inventoried their storage, and downloaded data collected by sensors deep underground.

The SKB bedrock borehole at the ice sheet margin.

With SKB discontinuing their Greenland science projects as of 2022, Greenland Guidance was selected to take over their surface hydrology project situated in the Two Boat Lake catchment. This is an exciting opportunity, and we welcome suggestions for scientific collaboration by anyone who reads this. More about the TBL project in an upcoming blog post!

Two Boat Lake with the ice sheet in the background.

Busy times

For Greenland Guidance, spring is the busiest time of year. This is when we support field parties remotely, take part in fieldwork ourselves, prepare for fieldwork in summer, and custom-build instruments for summer deployment. Nowadays we are also building and refurbishing instruments for use in the Himalayas for Utrecht University and the Indian Institute of Technology Roorkee. And we’ve expanded our area of expertise by now also focussing on ocean sciences through collaboration with MetOcean in Canada, and our new instrument platform Polar Monitoring.

Climate science enabled by Forloh

The glaciers in south Greenland are the canaries in the coal mine. They are located in the warmest part of Greenland. As the climate warms, glaciers further north will experience similar conditions in the future. So to learn about the future fate of the Greenland ice sheet, we must study how south Greenland glaciers fare in present-day climate conditions. For this reason we installed 3 draw wire ablation trackers (DWIATs) in south Greenland, and more instruments will follow. An important difference with most other science projects is that this project got funded by a pioneering, US-based company named Forloh.

Forloh site 1 as seen from above. The DWIAT instrument is located between helicopter and moulin (meltwater drainage hole).

For Greenland Guidance it all started when we were approached by Greenland logistics guru Kathy Young who was in touch with a company eager to contribute to climate science. A company appropriately selling warm outdoor clothing. Forloh was seeking to sponsor climate science in a cost-effective manner. With Greenland Guidance’s non-profit approach to science, a match was soon in the making.

Our missions with the instruments in south Greenland is not only that the observational data are shared freely with researchers across the globe, but also that the measurement locations are optimal for scientists. For this reason we asked the research community where they could see most value in having DWIATs monitor ice melt and motion. After this we decided on 3 sites requiring only short helicopter flights in south Greenland.

Winter temperatures – an example of Forloh scientific data displayed in the GG data portal. DWIATs also measure surface melt, latitude, longitude, altitude along with several system-diagnostics parameters. Note how DWIAT 1 got covered by winter snow accumulation judging from a reduced temperature variability on the right-hand side of the graph. But satellite transmissions keep coming in.

One monitoring site is right next to a moulin (meltwater drainage hole) on the main ice sheet. The second instrument is on the large, fast-flowing glacier named Eqalorutsit Kangilliit Sermiat (often called Qajuuttap Sermia) which is receiving increasing amounts of scientific attention these days. The third is on Nordbo glacier (Nordbogletsjer), a historic site where ice melt was also measured over 4 decades ago, providing an excellent opportunity to study the impacts of climate change since then.

Kathy Young and Steve Munsell, GG support crew along with Armin Dachauer, on Eqalorutsit Kangilliit Sermiat (also called Qajuuttap glacier) after installing a DWIAT.

Our helicopter charter took place on a Thursday in August. We were spared any weather delays, which are not uncommon when flying in Greenland. Our first site took some scouting as we had about 20 moulin candidate sites selected from satellite imagery. The second and third site were know before arrival, chosen to avoid crevasses and to match the historic measurement location, respectively. Instrument assembly/testing and drilling the draw wire into the glacier took 30-45 minutes per site. Even though the drilling at these wet sites proved difficult, we managed to stay on schedule, leaving some time for collecting footage at the spectacular moulin site.

We very much invite other scientists to collaborate scientifically or logistically in this project. Please do get in touch if you’re active in the region and have specific data needs.

The Forloh study area in south Greenland in red. The blue area contains GEUS PROMICE instrumentation. The red area is where Greenland Trees is active. Eqalorutsit Kangilliit Sermiat is the large glacier in the middle.

Revisiting ice monitoring equipment along the K-transect

Last summer, Greenland Guidance was again invited to assist with instrument maintenance on the western slope of the Greenland ice sheet. Here, along the iconic K-transect, Danish and Dutch scientist have been using automated measurement systems to monitor climate variables and surface ice melt for decades. As these weather stations, ice ablation trackers and other scientific measurement systems are exposed to harsh weather such as low temperatures, high wind speeds and countless thaw/freeze cycles, they need to be looked after once a year.

The PROMICE weather station at GEUS monitoring site KAN_L.

As in previous years, the Geological Survey of Denmark and Greenland (GEUS), the Institute for Marine and Atmospheric Research Utrecht (IMAU) and Greenland Guidance joined forces to visit all 10 measurement sites. Unlike the year before, the weather was reasonably well behaved; clouds and winds did not interfere too much with helicopter operations. In the higher ranges of our work area though we encountered a thick layer of saturated snow. Uncommonly warm air masses were over the ice sheet causing a serious melt event, severely complicating moving about in the soft, wet snow.

A draw wire ice ablation tracker one year after deployment.

Most equipment was found in good working order, requiring between 15 minutes and 3 hours of ground time per measurement site. The good news for Greenland Guidance was that all 4 custom-built draw wire ice ablation trackers (DWIATs) were fully functional and transmitting ice melt and motion data home.

A moulin fountain, spraying ice sheet meltwater 10 m up into the air.

One of the highlights of the 5-day fieldwork campaign was the sighting of what is best described as a “moulin fountain”. This rarely seen phenomenon occurs when overpressure from a large moulin (meltwater drainage hole in ice) is released via a crack in the ice to a smaller, neighbouring moulin.

Weather forecasts for Swiss scientists on the Greenland ice sheet

Greenland Guidance provided detailed weather forecasting for a Swiss science expedition on the Greenland ice sheet in spring this year. The expedition by the University of Fribourg took three weeks during which they camped in tents at 1700 m above sea level.

Weather is the largest safety hazard to expeditions at the camp’s position in southwest Greenland. Even in spring, temperatures can be dangerously low at -35 C, storms can damage tents, and whiteout conditions can make people lose camp even at 10 m distance. Also other dangers exist, yet it is unlikely to encounter dangerous crevasses or wildlife in this region; crevasses usually form where ice is thinner, closer to the ice sheet margin, whereas polar bears are spotted more frequently where their food sources live – on sea ice and at the coast.

Luckily the Swiss expedition did not encounter overly hazardous weather conditions on this occasion. Our weather forecasts helped them plan their days away from the safety of camp. Each morning at breakfast time they received an Iridium satellite text message containing up to 160 characters worth of weather information for their location and finetuned to their activities. Upon request, or if the situation required it, more weather messages would follow.

Later in the year, during an exceptional heat wave in summer, we passed over the region where the Swiss had camped. The surface of the area had turned into slush (snow saturated with meltwater), with a multitude streams where usually only snow can be seen. Good news for Swiss research on meltwater in snow. Less good news for those having to recover equipment temporarily stored on the ice sheet, now possibly stuck in refrozen meltwater…

Helicopter view of extreme melting at 1750 m elevation on the Greenland ice sheet 19 August 2021

Instrumenting Jakobshavn ice stream

Jakobshavn ice stream in Greenland is the most productive glacier in the world. In July of this year the University of Zürich (UZH) in Switzerland installed four Greenland Guidance instruments at Jakobshavn. Two glacier weather stations and two ice motion trackers measure ice movement via GPS in a detailed study of glacier dynamics.

GWS at Jakobshavn with Adrien Wehrlé (UZH)

Since their installation these instruments have been sending home the data they collected via the Iridium satellite network. The data feed into our data portal where it can be viewed and download by the university.

Because the instruments are positioned on Jakobshavn’s fast moving ice, the trackers are recording high ice velocities. And in only four months time they measured an elevation drop of about 25 m as the ice sheet flows towards the ocean.

Although winter hasn’t entirely arrived yet, the uppermost weather station at 1100 m above sea level already measured temperatures down to -35 °C. We are eager to find out whether temperatures down to -50 °C will be recorded come January, February or March. The lowest temperature measured by our instruments further south is “only” -43 °C.

Polar Monitoring: the website for rugged instruments

Greenland Guidance entered into a collaboration with MetOcean. From now on we offer polar instruments by both companies via the common portal! It’s the perfect match: MetOcean produces instruments for in the ocean, on sea ice and on land, whereas Greenland Guidance instruments are made for use on glacier ice and land. Together we have full polar coverage!

The Stokes Drifter is a compact drifting buoy that provides real-time surface current data.

Please do visit, have a look around, and tell your friends and colleagues. You won’t find these instrument cheaper anywhere on the European market, especially considering the decades of experience that have gone into making them extremely durable and easy to use.

The Greenland Guidance data portal

Our instruments measure whichever climate variable or glacier characteristic you’d like them to measure. They are built to survive extreme winds, temperatures far below freezing, long periods of darkness, burial by snow, and countless freeze/thaw cycles. Yet they measure with accuracy, draw little power, and are easy to transport. But in the end it’s all about the data. Getting those is of primary importance.

Example graph showing temperature data from the Greenland ice sheet.

All measured data are kept safe in the GG instrument’s data logger, awaiting the return of the instrument owner some time in the following years. But often it is beneficial to receive some or all data right away via satellite link. Our instruments feed their data straight into our data portal, where instrument owners can view and download their transmitted data. Every client gets a free, password-protected webpage where data are plotted in a clear and simple manner, and where transmitted data can be downloaded at the click of a button.

The DWIAT, measuring ice melt and ice motion.