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Cryospheric Sciences

modelling

Image of the Week – Karthaus Summer School 2017

Gloriously cloudless day for the fieldtrip to the Ötztal Alps [Credit: C. Reijmer].

Glaciologists often undertake fieldwork in remote and difficult to access locations, which perhaps explains why they happily travel to similar locations to attend meetings and workshops. The Karthaus Summer School, which focuses on Ice Sheets and Glaciers in the Climate System, is no exception. The idyllic village of Karthaus, located in the narrow Schnalstal valley in Südtirol (Italy), has been hosting this 10-day glaciology course nearly every year since 1995. In September, an international crowd of some 30+ PhD students and postdocs, and 11 lecturers assembled in Karthaus for the 2017 edition of this famous course, for an intensive program of lectures, food, some science, more food (with wine!), and lots of socialising.


The lecture theatre with a backdrop of green hills, on the day the cows came down from the hills [Credit: D. Medrzycka].

The morning sessions

A typical morning of the course involved four hours of lectures, which covered a wide range of topics including continuum mechanics, thermodynamics, ice-ocean interactions, ice cores, geophysics, and geodynamics, with a special focus on numerical modelling and its applications for investigating ice-climate interactions. The lectures covered fundamentals processes, their applications and limitations, and current knowledge gaps for a wide range of complex concepts related to ice dynamics. All our lecturers happily answered our (many) additional questions during the coffee and cake breaks, enjoyed in the fresh mountain air outside the lecture theatre.

 
 
 
 
 
 
 

The biggest challenge was not the group work itself, but trying to not get distracted by the sun and the hills surrounding us [Credit: V. Zorzut].

The afternoon sessions

After a three-course lunch, we spent the afternoon sessions applying the theory learned in the morning lectures. The group projects were designed to get us to go into more detail on certain topics, and work on real-world applications for specific research problems. We presented the results of our work at the end of the course during a 15 minute group presentation. For those who could afford a bit of free time after these sessions, the rest of the afternoon could be spent either hiking or trail running in the steep hills overlooking the village (trying to beat I. Hewitt’s time up Kruezspitze), playing football, chilling in the sauna, or catching up on some sleep before dinner.

 

The evenings

Everyone who has ever attended the Karthaus course mentions the food, complementing both the quality and (legendary) quantity of it. Every evening, we were served a memorable five course meal accompanied by generous amounts of local wine. Dessert was followed by musical entertainment, with inspired performances by Frank Pattyn on the piano. On the last evening, Frank was accompanied by Johannes Oerlemans who treated us to two of his original tango arrangements on the guitar, followed by a passionate rendition of Jacques Brel’s Le port d’Amsterdam by our own Kevin Bulthuis (vocals). We wrapped up each day of the course in the local bar, socialising, playing card games, sampling the local beers, and making our way through the many different flavours of schnaps and grappa. Big thanks to the owners, Paul and Stefania Grüner, and staff (with a special shout-out to Hannes) of the Goldene Rose Hotel, and the village of Karthaus, for taking great care of us!

Frank Pattyn (piano) and Johannes Oerlemans (guitar) performing an original tango arrangement [Credit: D. Medrzycka].


 

Out and about

On the penultimate day of the course the group headed to a number of glaciers in the Ötztal Alps. The excursion, which happened to take place on a perfectly cloudless day, gave us the opportunity to observe first hand the changes affecting glaciers in the region, and the impact of these retreating ice masses on the landscape and humans inhabiting it. It also provided a much needed break from the intense week! After walking down the ski slopes of the Hochjochferner, a small valley glacier accessible by cable car from Kurzras, we stopped to enjoy the sun and have lunch at the Schöne Aussicht (Bellavista) hut (2845 m a.s.l.). Those with more energy scrambled up to the ridge running along the Italian/Austrian border (3270 m a.s.l.), through at times knee-deep snow, to take a peak at the Hintereisferner, a valley glacier on the Austrian side of the border. Four of us continued on along the ridge, and by chance visited the laser scanner (LiDAR) system operated by researchers from the University of Innsbruck, used to monitor changes in surface elevation on the glacier.

Standing on the ridge running along the Italian/Austrian border. View onto the Hintereisferner [Credit: D. Medrzycka].


 

Final thoughts

The 10 day course was certainly an intensive (and intense) experience, and I would recommend it to all glaciology students without reservations, whether they are looking for a basic introduction to ice dynamics, or aiming to fill a few knowledge gaps. Whilst some of the topics covered in the course were only remotely related to my own PhD research (and far out of my comfort zone!), the lectures and project work forced me to think in alternate ways. Although I may have finished the course with more questions than I had at the start, I now know where to go look for the answers!

A big part of the experience was without a doubt the social aspect of the course. Between the never ending and excellent food (as a result of which some of us developed “food babies”), and the long evenings at the local bar (resulting in increasing amounts of sleep deprivation), there were plenty of opportunities to talk science, gain new insights into our ongoing research, and discuss ideas for future projects. As with all great Summer Schools, one of the major perks was the opportunity to hang out with fellow students, expand our network of fellow researchers, and establish the groundwork for continued professional collaborations. Huge thanks to the convenor, Johannes Oerlemans, the village of Karthaus, and all the lecturers and fellow students for a memorable 10 days! I am looking forward to working with all of you in the future.

The crowd of the Karthaus summerschool: 2017 edition [Credit: C. Reijmer].

Edited by Morgan Gibson and Clara Burgard


Dorota Medrzycka is a PhD candidate at the University of Ottawa (Canada), working with Luke Copland. Her research focuses on the dynamics of glaciers and ice caps in the Canadian High Arctic, with a focus on ice flow instabilities (including glacier surging). Her project combines field studies and remote sensing techniques to monitor ice motion, and gain insight into the factors controlling the variability in ice dynamics in the Canadian Arctic. Contact: dorota.medrzycka@uottawa.ca.

Image of the Week – A high-resolution picture of Greenland’s surface mass balance

Image of the Week – A high-resolution picture of Greenland’s surface mass balance

The Greenland ice sheet – the world’s second largest ice mass – stores about one tenth of the Earth’s freshwater. If totally melted, this would rise global sea level by 7.4 m, affecting low-lying regions worldwide. Since the 1990s, the warmer atmosphere and ocean have increased the melt at the surface of the Greenland ice sheet, accelerating the ice loss through increased runoff of meltwater and iceberg discharge in the ocean.


Simulating the climate with a regional model

To understand the causes of the recent ice loss acceleration in Greenland, we use the Regional Atmospheric Climate Model RACMO2.3 (Noël et al. 2015) that simulates the evolution of the surface mass balance, that is the difference between mass gain from snowfall and mass loss from sublimation, drifting snow erosion and meltwater runoff. Using this data set, we identify three different regions on the ice sheet (Fig. 1):

  • the inland accumulation zone (blue) where Greenland gains mass at the surface as snowfall exceeds sublimation and runoff,

  • the ablation zone (red) at the ice sheet margins which loses mass as meltwater runoff exceeds snowfall.

  • the equilibrium line (white) that separates these two areas.

From 11 km to 1 km : downscaling RACMO2.3

To cover large areas while overcoming time-consuming computations, RACMO2.3 is run at a relatively coarse horizontal resolution of 11 km for the period 1958-2015. At this resolution, the model does not resolve small glaciated bodies (Fig. 2a), such as narrow marginal glaciers (few km wide) and small peripheral ice caps (ice masses detached from the big ice sheet). Yet, these areas contribute significantly to ongoing sea-level rise. To solve this, we developed a downscaling algorithm (Noël et al., 2016) that reprojects the original RACMO2.3 output on a 1 km ice mask and topography derived from the Greenland Ice Mapping Project (GIMP) digital elevation model (Howat et al., 2014). The downscaled product accurately reproduces the large mass loss rates in narrow ablation zones, marginal outlet glaciers, and peripheral ice caps (Fig. 2b).

Fig. 2: Surface mass balance (SMB) of central east Greenland a) modelled by RACMO2.3 at 11 km, b) downscaled to 1 km (1958-2015). The 1 km product (b) resolves the large mass loss rates over marginal outlet glaciers [Credit: Brice Noël].

 

The high-resolution data set has been successfully evaluated using in situ measurements and independent satellite records derived from ICESat/CryoSat-2 (Noël et al., 2016, 2017). Recently, the downscaling method has also been applied to the Canadian Arctic Archipelago, for which a similar product is now also available on request.

Endangered peripheral ice caps

Using the new 1 km data set (Fig. 1), we identified 1997 as a tipping point for the mass balance of Greenland’s peripheral ice caps (Noël et al., 2017). Before 1997, ablation (red) and accumulation zones (blue) were in approximate balance, and the ice caps remained stable (Fig. 3a). After 1997, the accumulation zone retreated to the highest sectors of the ice caps and the mass loss accelerated (Fig. 3b). This mass loss acceleration was already reported by ICESat/CryoSat-2 satellite measurements, but no clear explanation was provided. The 1 km surface mass balance provides a valuable tool to identify the processes that triggered this recent mass loss acceleration.

Fig. 3: Surface mass balance of Hans Tausen ice cap and surrounding small ice bodies in northern Greenland before (a) and after the tipping point in 1997 (b). Since 1997, the accumulation zone (blue) has shrunk and the ablation zone (red) has grown further inland, tripling the pre-1997 mass loss [Credit: Brice Noël].

 

Greenland ice caps are located in relatively dry regions where summer melt (ME) nominally exceeds winter snowfall (PR). To sustain the ice caps, refreezing of meltwater (RF) in the snow is therefore a key process. The snow acts as a “sponge” that buffers a large amount of meltwater which refreezes in winter. The remaining meltwater runs off to the ocean (RU) and contributes to mass loss (Fig. 4a).

Before 1997, the snow in the interior of these ice caps could compensate for additional melt by refreezing more meltwater. In 1997, following decades of increased melt, the snow became saturated with refrozen meltwater, so that any additional summer melt was forced to run off to the ocean (Fig. 4b), tripling the mass loss.

Fig. 4: Surface processes on an ice cap: the ice cap gains mass from precipitation (PR), in the form of rain and snow. a) In healthy conditions (e.g. before 1997), meltwater (ME) is partially refrozen (RF) inside the snow layer and the remainder runs off (RU) to the ocean. The mass of the ice cap is constant when the amount of precipitation equals the amount of meltwater that runs off. b) When the firn layer is saturated with refrozen meltwater, additional meltwater can no longer be refrozen, causing all meltwater to run off to the ocean. In this case, the ice cap loses mass, because the amount of precipitation is smaller than the amount of meltwater that runs off [Credit: Brice Noël].

  In 1997, following decades of increased melt, the snow became saturated with refrozen meltwater, so that any additional summer melt was forced to run off to the ocean, tripling the mass loss.

We call this a “tipping point” as it would take decades to regrow a new, healthy snow layer over these ice caps that could buffer enough summer meltwater again. In a warmer climate, rainfall will increase at the expense of snowfall, further hampering the formation of a new snow cover. In the absence of refreezing, these ice caps will undergo irreversible mass loss.

What about the Greenland ice sheet?

For now, the big Greenland ice sheet is still safe as snow in the extensive inland accumulation zone still buffers most of the summer melt (Fig. 1). At the current rate of mass loss (~300 Gt per year), it would still take 10,000 years to melt the ice sheet completely (van den Broeke et al., 2016). However, the tipping point reached for the peripheral ice caps must be regarded as an alarm-signal for the Greenland ice sheet in the near future, if temperatures continue to increase.

Data availability

The daily, 1 km Surface Mass Balance product (1958-2015) is available on request without conditions for the Greenland ice sheet, the peripheral ice caps and the Canadian Arctic Archipelago.

Further reading

Edited by Sophie Berger


Brice Noël is a PhD Student at IMAU (Institute for Marine and Atmospheric Research at Utrecht University), Netherlands. He simulates the climate of the Arctic region, including the ice masses of Greenland, Svalbard, Iceland and the Canadian Arctic, using the regional climate model RACMO2. His main focus is to identify snow/ice processes affecting the surface mass balance of these ice-covered regions. He tweets as: @BricepyNoel Contact Email: b.p.y.noel@uu.nl

Image of The Week – Ice Flows!

Image of The Week – Ice Flows!

Portraying ice sheets and shelves to the general public can be tricky. They are in remote locations, meaning the majority of people will never have seen them. They also change over timescales that are often hard to represent without showing dramatic images of more unusual events such as the collapse of the Larsen B Ice Shelf.  However, an app launched in the summer at the SCAR (Scientific Committee for Antarctic Research) Open Science Conference in Kuala Lumpur set out to change this through a game. Developed by Anne Le Brocq from the University of Exeter, this game is aptly named – Ice Flows!


The game in a nutshell!

Ice Flows is a game that allows the player to control various variables of an ice shelf (floating portion of an ice sheet) environment, such as ocean temperature and snowfall, and see the changes that these cause. For example, increasing the amount of snowfall increases the ice thickness but increasing the ocean temperature causes thinning of the ice shelf. The aim of the game is to help penguins feed by altering the variables to create ice shelf conditions which give them access to the ocean. Although the game is based around penguins, importantly, it is changing the ice shelf environment that the player controls, this allows a player to investigate how changing environmental conditions affect the ice. Our Image of the week shows a still from the game, where the player has created ice conditions which allow the penguins to dive down and catch fish.

What is the educational message?

The polar regions are constantly changing and assigning these changes to either natural cycles or anthropogenic (human induced) climate change can be tricky. Ice shelves tend to only hit the news when large changes happen, such as the recent development of the Larsen C rift which is thought to be unrelated to the warming climate of the region but may still have catastrophic consequences for the ice shelf. Understanding that changes like these can sometimes be part of a natural process can seem conflicting with the many stories about changes caused by warming. That’s why ice flows is a great way to demonstrate the ways in which ice shelves can change and the various factors that can lead to these changes. And the bonus chance to do this with penguins is never going to be a bad thing!

The game allows players to visualise the transformation of ice sheet to ice shelf to iceberg. This is an especially important educational point given the confusing ways that various types of ice can be portrayed by the media; reports, even if factually correct, will often jump from sea ice to ice shelves and back (see this example). It is also common for reports to cloud the climate change narrative by connecting processes thought to be due to natural causes (such as the Larsen C rift) to a warming climate (such as this piece). This confusion is something I often see reflected in people’s understanding of the cryosphere. In my own outreach work I start by explicitly explaining the difference between ice shelves and sea ice (my work is based on ice shelves). Even so, I can usually guarantee that many people will ask me questions about sea ice at the end of my talk.

Xue Long the Snow Dragon Penguin [Credit: Ice Flows game ]

Despite the messages that it is trying to convey, the app doesn’t come across as pushing the educational side too much. There is plenty of information available but the game also has genuinely fun elements. For example, you can earn rewards and save these to upgrade your penguins to some extravagant characters (my favourite has to be Xue Long – the snow dragon penguin!) Although the focus may be drawn towards catching the fish for the penguins while you’re actually playing, it would be hard for anyone to play the game and walk away without gaining an understanding of the basic structure of an ice shelf and how various changing environmental factors can affect it.

Developing the game…

The game was developed by Anne Le Broq in collaboration with games developers Inhouse Visual and Questionable Quality, using funding from the Natural Environment Research Council. Of course, many scientific researchers were also involved to ensure that the game was as scientifically accurate as possible whilst still remaining fun to play.

A key challenge in developing the game was modelling the ice flow. In order to be used in the app, the ice flow model needed to represent scientific understanding as well as being reactive enough to allow the game to be playable. This required some compromise, as one of the scientists involved in the development, Steph Cornford (CPOM, University of Bristol), explains on the CPOM Blog:

On one hand, we wanted the model to reflect contemporary understanding well enough for students to learn about ice sheets, ice shelves, and Antarctica in particular. On the other, the game had to be playable, so that any calculations needed to be carried out quickly enough that the animation appeared smooth, and changing any of the parameters (for example, the accumulation rate) had to lead to a new steady state within seconds, to make the link between cause and effect clear.

— Steph Cornford

The resulting model works really well, creating a fun, challenging and educational game! See for yourself by downloading the free to play game from your app store, or online at www.iceflowsgame.com!

Further reading

  • Find out more about the game on the University of Exeter website or visit the game’s own website here.
  • You can read in more detail about Steph’s modelling here.

Edited by Emma Smith


Sammie Buzzard has recently submitted her PhD thesis where she has developed a model of ice shelf surface melt, focusing on the Larsen C Ice Shelf. She is based at the Centre for Polar Observation and Modelling within the University of Reading’s Department of Meteorology. She blogs about her work and PhD life in general at https://iceandicing.wordpress.com/ and tweets as @treacherousbuzz.

Image of The Week – The Pulsating Ice Sheet!

Image of The Week – The Pulsating Ice Sheet!

During the last glacial period (~110,000-12,500 years ago) the Laurentide Ice Sheet (North America) experienced rapid, episodic, mass loss events – known as Heinrich events. These events are particularly curious as they occurred during the colder portions of the last glacial period, when we would intuitively expect large-scale mass loss during warmer times. In order to understand mass loss mechanisms from present-day ice sheets we need to understand what happened in the past. So, how can we better explain Heinrich events?


What are Heinrich Events?

During a Heinrich event large swarms of icebergs were discharged from the Laurentide Ice Sheet into the Hudson Strait and eventually into the North Atlantic Ocean. This addition of fresh water to the oceans caused a rise in sea level and a change in ocean currents and therefore climate.

We know about these events by studying glacial debris that was transported from the ice sheet into the oceans by the icebergs and eventually deposited on the ocean floor. From studying ocean-sediment records we know that Heinrich events occurred episodically during the last glacial period but not on at a regular intervals. Interestingly, when compared to temperature records from Greenland ice cores, it can be seen that the timing of Heinrich events coincides with the cold phases of Dansgaard–Oeschger (DO) cycles – rapid temperature fluctuations which occurred during the last glacial period (see our previous post).

the timing of Heinrich events coincides with the cold phases of Dansgaard–Oeschger (DO) cycles

What do we think causes them?

A new study, published last month in Nature, uses numerical modelling to show how pulses of warm ocean water could trigger Heinrich events. Our image of the week (Figure 1) illustrates the proposed mechanism for one event cycle:

  • a) Ice sheet at it’s full extent, grounded on a sill (raised portion of the bed, at the mouth of the Hudson Strait). Notice the sill is around 300m below sea level at this time.
  • b) A pulse of sub-surface water (purple) warms by a few degrees, encouraging iceberg calving at the glacier front and causing the ice begin to retreat from the sill.
  • c) As the ice retreats, it becomes unstable due to an inwards sloping bed (see our previous post on MISI). This leads to sudden rapid retreat of the ice – characteristic of Heinrich events.
  • d) Due to ice loss and thus less mass depressing the bed, the bed will slowly rise (Glacial Isostatic Adjustment), eventually the sill has risen to a level which cuts off the warmer water from the ice front and the ice can slowly advance again.

Once the ice has advanced back to it’s maximum extent (a) it will slowly depress the bed again, allowing deeper, warmer water to reach the ice front and the whole cycle repeats!

The authors of this study used this model to simulate Heinrich events over the last glacial period and were able to accurately predict the timing of Heinrich events, as known from ocean sediment records. Check out this video to see the model in action!!

Why is it important?

This study shows that the proposed mechanism probably controlled the onset of rapid mass-loss Heinrich events in the past and more generally that such mechanisms can cause the rapid retreat of marine terminating glaciers. This is important as it adds to our understanding of the stability (or instability) of present day marine terminating glaciers – such as the West Antarctic Ice Sheet! If such rapid mass loss happened regularly in the past we need to know if and how it might happen in the future!

such mechanisms can cause the rapid retreat of marine terminating glaciers.


Check out the full study and the news article summarising the findings here:

Katabatic winds – A load of hot (or cold) air?

Katabatic winds – A load of hot (or cold) air?

It might seem obvious that a warming world will lead to a reduction in glacial ice cover, but predicting the response of glaciers to climatic change is no simple task (even within the short term). One way to approach this problem is to come up with relationships which describe how glaciers interact with the world around them, for example, how the ice interacts with the air above it. Our post today delves into the world of ice-air interaction and describes some of the problems encountered by those who are investigating it, in particular the problem of modelling katabatic winds! Not sure what we are talking about…then read on to find out more! 


What are katabatic winds?

Anyone who has stood on, or in front of a glacier on a clear, sunny day has no doubt felt the bitter chill of a katabatic wind, forcing them to don a warm jacket and lose their chance at that lovely “glacier tan”. Katabatic winds (derived from the Greek word katabasis, meaning ‘downhill’) develop over snow and ice surfaces because the 0°C ice surface cools the air just above it. This cold, dense air then flows downhill under the force of gravity (Fig. 1 and Fig. 2). This is not recent news and such wind chill has no doubt punished glaciologists and explorers for the last century or more –  Mawson’s Description of the 1911-1914 Australian Antarctica Expedition is aptly named “The Home of the Blizzard“. However, despite being well known, this phenomenon still causes much uncertainty when it comes to modelling the melting of glacier ice surfaces around the world.

Soon gusts swept the tops of the rocky ridges, gradually descending to throw up the snow at a lower level. Then a volley raked the Hut, and within a few minutes we were once more enveloped in a sea of drifting snow, and the wind blew stronger than ever. – Mawson, 1915, The Home of the Blizzard

Figure 2: The view from the upper reaches of Tsanteleina Glacier in the western Italian Alps (Val d’Rhemes, Aosta). Katabatic winds generally flow in a down-glacier direction – here, from right to left [Credit: T Shaw].

Challenges for modelling

Air temperature is really important in determining how much a glacier melts and we need to know as much about it as possible to provide accurate predictions now and into the future. This is particularly relevant because the warmer it gets, the more energy is available to melt ice and seasonal snow. Unfortunately though, we don’t have an infinite supply of meteorological observations (e.g. air temperature, wind speed etc) at many locations we are interested in. As a result, we have to make simple assumptions about what the weather is doing at a remote, far away glacier. One such simple assumption is based upon the fact that air temperature typically decreases with increasing elevation, and so if we know the elevation of a location we are interested in, we can assume a ‘likely’ temperature. The rate of change in temperature with elevation is known as a ‘lapse rate’.

Air temperature is really important in determining how much a glacier melts…the warmer it gets, the more energy is available to melt ice and seasonal snow.

When predicting glacier melt, it is common practice to use a lapse rate which stays constant in time and space. This is convenient as we often don’t know the actual lapse rate at a given location, but this often ignores things happening at the surface of the Earth. An important example of this is when we have katabatic winds over glaciers!

When conditions are warm, and skies are clear, the cooling of the air above the ice surface, means that the application of a lapse rate is fairly useless, or close to it [Greuell and Böhm, 1998]! That is because the cooling from the surface continues as air flows down the glacier, typically creating colder temperatures at lower elevations, the opposite of the typical lapse rate assumption that models will apply.

‘Bow-shaped’ temperature vs. elevation relationships

To complicate matters for people trying to model the air temperature over glaciers, the effect of surface cooling is not just dependent on the amount of time an air parcel is in contact with the ice surface but also the characteristics of the ice surface it has been in contact with. In fact, after cooling on their descent down-glacier, air parcels have been documented to warm again, leaving interesting slightly “bow-shaped” curves to the temperature-elevation relationship. This effect has been found for the Swiss Haut Glacier d’Arolla and the Italian Tsanteleina Glacier (Fig. 3c,d). A new model approach to tackling this bow-shaped problem has been presented by recent research [Ayala et al., 2015] and offers a means of accounting for katabatic winds in glacier models. Nevertheless, more data and more work are still needed to generalise these models [Shaw et al., in review].

Figure 3: Relationship between elevation and air temperature on three different glaciers in the western Alps. Miage (Italy), Tsanteleina (Italy) and Arolla (Switzerland). Glaciers are represented using the mean of all data available (green), the top 10% of off-glacier temperatures (P90 – red) and the bottom 10% of off-glacier temperatures (P10 – blue), plus one standard deviation. The debris-covered Miage Glacier does not demonstrate a classic katabatic flow regime and therefore temperature corresponds well to elevation even under warm conditions [Credit: T Shaw, unpublished].

after cooling on their descent down-glacier, air parcels have been documented to warm again, leaving interesting slightly “bow-shaped” curves to the temperature-elevation relationship.

Air temperatures across debris-covered glaciers

As you may have read in our previous post on the topic, debris-covered glaciers behave in a different way to those with a clean ice surface. Detailed observations of air temperature across a debris-covered glacier show that the glacier responds to the heating of surface debris in the sunlight and a consequent warming of the lower atmosphere [Shaw et al., 2016]. Because of this, air temperature conforms very strongly to the elevation dependency that is assumed when using a lapse rate. Although very local variations of air temperature on other debris-covered glaciers cannot be well estimated by a lapse rate [Steiner and Pellicciotti, 2016], the insulating effect of thick debris cover means that the current approach to using simple lapse rates for estimating air temperature over debris-covered glaciers could be suitable.

Nevertheless, challenges for accurately representing air temperature above glaciers without debris cover remain. The fact that globally averaged temperatures are expected to rise over the current century (areas at high latitudes have shown a stronger warming trend) [Collins et al, 2013], the applicability of using lapse rates could further diminish. Recent patterns of warmer-than-average temperatures also suggest a difficulty of accurately estimating on-glacier temperatures in the short-term. For example, for the period of May 2015 – August 2016, every month beat the previously held record for warmest globally average temperature (GISTEMP). Imagine the bow-shaped problem to that!

Edited by Matt Westoby and Emma Smith


Thomas Shaw is a PhD student in the Department of Geography at Northumbria University, UK. His research is focused on the spatial and temporal variance in near-surface air temperature across debris-covered and debris-free glaciers in the western Italian Alps. As well as conducting research in the Alps, he is also very interested in glaciers and their processes on Svalbard (Norwegian Arctic) and has spent plenty of time studying above, or within (!), ice at high latitudes. Contact e-mail: thomas.shaw@northumbria.ac.uk

Ice-Hot News : The “Oldest Ice” quest has begun

Ice-Hot News : The “Oldest Ice” quest has begun

This is it! The new European horizon 2020 project on Oldest Ice has been launched and the teams are already heading out to the field, but what does “Old Ice” really mean? Where can we find it and why should we even care? This is what we (Marie, Olivier and Brice) will try to explain somewhat.


Why do we care about old ice, ice cores and past climate?

Figure 1: Drilling an ice core [Credit: Brice Van Liefferinge]

Figure 1: Drilling an ice core [Credit: Brice Van Liefferinge]

Unravelling past climate and how it responded to changes in environmental conditions (e.g. radiative forcing) is crucial for our understanding of the current climate and for predicting how climate will likely change in the future.

Ice cores contain unique and quantitative information on the past climate (e.g. atmospheric gas concentration). The caveat is that at the moment, we can “only” go back up to 800,000 years at EPICA Dome C ice core (Parrenin et al, 2007).

Nonetheless, marine records tell us that during the Mid-Pleistocene there was a major climate transition (0.8-1.2 million years ago): a change in the frequency of glacial-interglacial cycles in the Northern Hemisphere. Instead of an ice age every 40,000 year, the climate changed to what is termed a “100,000 year world”. Unfortunately, the time resolution of marine records are too coarse to provide details on the mechanisms behind such climate changes. We must therefore rely on ice cores to obtain a high enough temporal resolution. Furthermore, the ice traps air bubbles and can therefore provide a record of the atmospheric composition that can be used to directly measure the paleo atmosphere through the transition.

The new European project ‘Oldest ice’ was set up for this very objective: crack the Mid-Pleistocene Transition climate. It brings together engineers, experimentalists and modellers from 14 Universities around the world.

In this post, we will focus on the first mission of the project: locating areas with million year old ice in Antarctica. The next steps will be to:

  • develop the drilling technology,

  • improve our geophysical knowledge of the identified site,

  • and finally, reach the “holy grail”: recover ice from the very base of the ice sheet with a target age of 1.5 Million years.

The whole project is anticipated to last 10 years!

The new European project ‘Oldest ice’ was set up for this very objective: crack the Mid-Pleistocene Transition climate

The first mission: “Where to find million year old ice?”

Oldest Ice (ice more than 1 mio. years old) can only be recovered in Antarctica, but where exactly? This question has to be answered in a two-step approach:

  1. On a large scale, we must first narrow down places in Antarctica where Oldest Ice might be found. To do that, we rely on models.

  2. Then, we can focus our analysis on those regions by gathering field data in the form of airborne radar surveys. Further ground-based work is currently taking place.

On a larger scale, Oldest Ice in Antarctica requires:

  1. Thick ice and cold bed. We need thick ice to reconstruct past climate variations with sufficient temporal resolution (e.g. is there enough ice to measure air bubbles or other climate markers). However, the thicker the ice, the higher the basal temperature. If the bottom of the ice is too warm, the ice at the base will start to melt, potentially destroying the Oldest Ice of the ice sheet.
    Finding a suitable drill site hence requires a good trade-off between thickness and cold-bed conditions.

  2. Slow-moving ice. This is found mainly at the centre of the ice sheet. Imagine this: if ice were to flow at as little as 1 m per year over a period of 1.5 Million years, it would have travelled 1,500 km over that time interval! However, there is a catch: slow-moving areas are also low-accumulation areas, and low accumulation means warmer ice. This is because the ice is cooled by the addition of cold snow at the surface that then gets transformed to ice and then travels downwards. Indeed, the greater the accumulation, the deeper the “cold snow” can penetrate into the ice sheet!

  3. Undisturbed ice. In order to obtain an interpretable climate record, the ice recovered from the drill needs to be stratigraphically ordered, i.e. no mixing of the ice can have occurred so that we can assume that time increases with depth when we measure ice composition down the core. Variations in the height of the bedrock can induce such ice mixing.

(more information can be found in Van Liefferinge and Pattyn (2013))

Figure 2. Potential locations of cold bed (basal temperatures 2000 m), slow motion (horizontal flow speeds <2m/yr) The colour bar represents the basal temperature. The two insets focus on Dome C and Dome F, two areas highly likely to store million year old ice. [Credit: Brice Van Lieffering, updated from Van Liefferinge, B. and Pattyn, 2013]

Figure 2. Potential locations of cold bed (basal temperatures 2000 m), slow motion (horizontal flow speeds <2m/yr) The colour bar represents the basal temperature. The two insets focus on Dome C and Dome F, two areas highly likely to store million year old ice. [Credit: Brice Van Lieffering, updated from Van Liefferinge, B. and Pattyn, 2013]

While boundary conditions such as ice thickness and accumulation rates are relatively well constrained, the major uncertainty remains in determining thermal conditions at the ice base. The thermal conditions depend on the geothermal heat flow (the flux of “energy” provided by the Earth which conducts heat into the crust) underneath the ice sheet. But to measure the geothermal heat flow, you need to reach the bed.

We need to find the ideal drilling location which would satisfy all these conditions – a bit of a “Goldilocks’ choice”: thick ice but not too much, low accumulation but not too low, low geothermal heat flow but high enough to not get folded basal ice. To do this we use several models: a simple one which calculates the minimum geothermal heat flow needed to reach the pressure melting point that we can then compare to data sets, and a more complex one resolving in three dimensions the temperature field with thermomechanical coupling (i.e. linking the ice-flow component to the heat-flow component). The combination of modelling approaches shows that the most likely oldest ice sites are situated near the ice divide areas (close to existing deep drilling sites, but in areas of smaller ice thickness) (see Figure 2).

Give it a go: Try to find million year old ice yourself using this Matlab© tool: http://homepages.ulb.ac.be/~bvlieffe/old-ice.html

The combination of modelling approaches shows that the most likely oldest ice sites are situated near the ice divide areas

On finer scales: we need deep radiostratigraphy and age modelling

Radar profiles

Figure 3. Radargram from the new OIA radar survey (Young et al., in review) with isochrones interpreted in red [Credit: Marie Cavitte]

Figure 3. Radargram from the new Oldest Ice A radar survey (Young et al., in review) with isochrones interpreted in red [Credit: Marie Cavitte]

Radargrams (see figure 3) are powerful tools to observe the internal structure of the ice: variations in density, acidity and ice fabric all can create conductivity contrasts, which result in radar visual stratigraphy. Below the firn column (the compacting snow, up to 100 m thick), most returns are related to acidity variations, corresponding to successive depositional events (i.e. snowfall). Radar stratigraphy in this case can be considered isochronal, i.e. every visible line (see figure 3) were formed at the same moment, (Siegert et al., 1999). Such radar isochrones can then be traced for kilometres throughout the ice sheet where radar data has been acquired. When radar lines intersect an ice core site, the radar stratigraphy can then be dated by matching the isochrone-depths to the ice core depths at the site and then transferring the age-depth timescale.

This allows to date entire sub-regions. However, the very bottom of the ice column is often difficult to interpret: radar isochrones cannot always be continuously followed from the ice core.

Radargrams are powerful tools to observe the internal structure of the ice

The newly acquired Oldest Ice A radar survey (Young et al., in review) over the Dome C region (see figure 2 for location) gives very rich stratigraphic information and the proximity of the EPICA Dome C ice core has allowed the dating of the isochrones. The ice sheet in this area could only be dated to ~360,000 years (Cavitte et al., 2016) and not further back in time because deeper isochrones are tricky to tie to the ice core, and other times, there is no clear signal (deep scattering ice, visible near the bedrock, at the bottom of Figure 3). As such, we need an age model to try to describe the age-depth relation below the deepest dated isochrones.

Modelling the ice

Figure 4. More precise analysis of the Dome C Oldest Ice target, with the lines representing the Oldest Ice A airborne survey collected in winter 2015/16 (Young et al., in review). The colours represent the modelled age of the ice 60 meters above the bedrock, in thousands of years. We can see that this whole region has a lot of potential for recovering million year old ice. [Credit: Olivier Passalacqua]

Figure 4. More precise analysis of the Dome C Oldest Ice target, with the lines representing the Oldest Ice A airborne survey collected in winter 2015/16 (Young et al., in review). The colours represent the modelled age of the ice 60 meters above the bedrock, in thousands of years. We can see that this whole region has a lot of potential for recovering million year old ice. [Credit: Olivier Passalacqua]

The age of the ice primarily depends on its vertical velocity, so we can use a simple 1D model to describe the motion of the ice in the vertical direction. We run the model for an ensemble of vertical velocity profiles and basal melt rates, and consider the distribution of the basal ages (i.e. model ages) given by the profiles that reproduce the observations the best (i.e. isochrones ages).

We need an age model to try to describe the age-depth relation below the deepest dated isochrones

After running the model, it appears that many areas of the Oldest Ice A survey region host very old ice (see red and yellow dots on figure 4 which represent ages > 1 million years). A high enough bottom age gradient, provided by the dated isochrones, is required to ensure sufficiently old ice as a drilling target. Following initial calculations, it will probably be a better choice to drill on the flank of the bedrock relief than on its top.

So in the end, where do we find the oldest ice?

We have to find areas which provide a good compromise between thick ice (for the a good temporal resolution in the ice core) but not too thick (to avoid basal melting). The best sites will be the ones close to the surface ridge (to ensure limited displacement of the ice), standing above the surrounding subglacial lakes, and for which a lot of undated isochrones below the last dated isochrone are visible.

To find out more about Beyond EPICA and keep track of progress visit the project  website and follow @OldestIce on twitter!

Edited by Sophie Berger


Brice Van Liefferinge is a PhD student and a teaching assistant at the Laboratoire de Glaciology, Université libre de Bruxelles, Belgium. His research focuses on the basal conditions of the Antarctic ice sheet. He tweets as @bvlieffe.

Marie Cavitte is a PhD student at the Institute for Geophysics at the University of Texas at Austin, Texas. Her research focuses on understanding radar internal stratigraphy and using it as a means to constrain the temporal stability of the East Antarctic Ice Sheet interior.

Olivier Passalacqua is a PhD student at the Laboratoire de Glaciologie et Géophysique de l’Environnement, Grenoble, France.

Members of the consortium

  • Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI, Germany), Coordination
  • Institut Polaire Français Paul Émile Victor (IPEV, France)
  • Agenzia nazionale per le nuove tecnologie, l’energia e lo sviluppo economico sostenibile (ENEA, Italy
  • Centre National de la Recherche Scientifique (CNRS, France)
  • Natural Environment Research Council – British Antarctic Survey (NERC-BAS, Great Britain)
  • Universiteit Utrecht – Institute for Marine and Atmospheric Research (UU-IMAU, Netherlands)
  • Norwegian Polar Institute (NPI, Norway)
  • Stockholms Universitet (SU, Sweden)
  • Universität Bern (UBERN, Switzerland)
  • Università di Bologna (UNIBO, Italy)
  • University of Cambridge (UCAM, Great Britain)
  • Kobenhavns Universitet (UCPH, Denmark)
  • Université Libre de Bruxelles (ULB, Belgium)
  • Lunds Universitet (ULUND, Sweden)

Non-Europan partners

  • Institute for Geophysics, University of Texas at Austin (UTIG, US)
  • Australian Antarctic Division (AAD, Australia)

Image of the week – Our salty seas and how this affects sea ice growth

Image  of the week – Our salty seas and how this affects sea ice growth

Earth’s oceans are not simply just water, they are a complicated multi-component fluid consisting of water and dissolved salts (ask anyone who has tried to drink it!). The existence of these salts has a significant impact on global ocean circulation. Nowhere is this more significant than in the polar oceans where it is one of the key factors influencing sea ice formation. In this week’s image of the week we are going to show you how freezing ocean water is a little more complicated than you may think!


The salinity and temperature of ocean water affect its density; essentially how much it weighs. Typical ocean densities are around 1000 kg/m3  and, depending on the temperature and salinity may vary by up to 1 %. This seems tiny, but these small changes in density are what drive the thermohaline circulation, the dominant large-scale ocean circulation. The density of sea water, as a function of temperature and salinity, is expressed in terms of the equation of state  (a mathematical way of describing the density of sea water in relation its temperature and salinity). Contours of the equation of state of seawater are shown in this week’s Image of the Week. The figure is from a recent paper by Mary-Louise Timmermans and Steven Jayne, who try to understand how changes in Arctic temperature will influence the density, and therefore the circulation, in the Arctic Ocean. The y-axis is temperature, and the x-axis is salinity. The black lines are density contours. The dashed line plots the freezing point of water.

Sea Ice Formation

Sea ice begins to form when ocean water is brought to this freezing point. If one was to put a cup of tap water into a freezer, ice would begin to form at 0 °C. But talk to a group of polar ocean modellers, and they will tell you the freezing point of water is about -1.8 °C. How can this be?

Let’s got back to our figure for some clues. Looking at the dashed line representing freezing point of ocean water you will notice that as the salinity increases, the freezing point decreases. So an increase in salinity of sea-water suppresses its freezing point. Just like how salt is used to melt ice in winter, it prevents the water from reaching its freezing point until the water reaches roughly -2 °C.

How does this all link together?

When the ocean gets cold, the influence of temperature on density changes, affecting how rapidly sea ice can form. Take a look at the bending of the black contours as the temperature is reduced to zero and below. Whereas in “normal”, warm contexts, a decrease in temperature leads to an increase in density, this changes as the temperature approaches 0 °C. As the ocean cools, the top-most, coldest water typically sinks, and is replaced by warmer water from below, driving ocean circulation convection. It therefore can take a long time to bring the surface of the ocean to near 0 °C. Since there is salt in the ocean, the water can reach colders temperatures where something very different happens. As the water continues to cool, the coldest water no longer sinks, and may even float, with sea-ice formation happening rapidly.

The formation process of sea ice, and its relationship to the ocean it forms out of is an extremely complicated and rich phenomenon, and it all depends on salt!

Further Reading

  • Mary-Louise Timmermans and Steven R. Jayne, 2016: The Arctic Ocean Spices Up. J. Phys. Oceanogr. 46, 1277–1284, doi: 10.1175/JPO-D-16-0027.1.
  • For more on sea ice check the National Snow and Ice Data Center (NSIDC) website – All About Sea Ice!

Edited by Emma Smith


Image of the Week – See How Seasonal Sea Ice Decline Differs!

Image of the Week – See How Seasonal Sea Ice Decline Differs!

Why do we care about sea ice in the first place?

  • Sea ice is important for several components of the climate system.
  • Due to its high albedo, sea ice reflects a high amount of the incoming solar radiation and is therefore relevant for the Earth’s energy budget.
  • Sea ice inhibits the exchange of heat, moisture and momentum between ocean and atmosphere, which usually occur at the sea surface.
  • Where sea ice forms, it releases heat and salt. When sea ice melts, it takes up heat and reduces the salinity of the surrounding water. Sea ice therefore redistributes heat and freshwater.
  • Sea ice provides habitat for plants and animals and hunting grounds for animals and indigenous populations.
  • Sea ice is an obstacle for shorter commercial shipping routes through the Arctic and oil and gas drilling.

The Arctic sea-ice cover is decreasing!

In recent decades, the Arctic sea-ice cover has been retreating rapidly. As we care about sea ice (see above!), scientists have been trying to understand this decline and to define a time span over which the sea-ice cover is expected to totally disappear (usually below 1 million km²). Up to now, research has mostly focused on the Arctic summer sea-ice cover, as this is expected to disappear much sooner than the winter cover. However, it is also of interest how winter sea-ice cover will evolve in the future and has evolved in the past.

What is meant by summer and winter sea-ice cover?

The Arctic sea-ice area follows a seasonal cycle with a maximum in late winter and a minimum in late summer (see figure below).

Figure 2: Arctic sea-ice concentration climatology from 1981-2010, at the approximate seasonal maximum (late winter) and minimum (late summer) levels based on passive microwave satellite data. (Credit : National Snow & Ice Data Center )

Figure 2: Arctic sea-ice concentration climatology from 1981-2010, at the approximate seasonal maximum (late winter) and minimum (late summer) levels based on passive microwave satellite data. (Credit : National Snow & Ice Data Center )

So, what about our Image of the Week?

In their study, Bathiany et al. (2016) compare the characteristics of the summer and winter sea-ice loss in the Arctic in general circulation models (GCMs). They investigate the changes in sea-ice area as a function of global annual mean surface air temperature. Summer sea-ice area (see red points) declines more linearly, “with no or a less pronounced change in slope”. Winter sea-ice area (see blue points), however, declines slowly at first and then more abruptly (this can still mean several years to decades, depending on the projection scenario used!). This abrupt decrease starts when ice volume is already very small.

How can this be?

Summer sea ice is distributed very heterogeneously over the Arctic, with very thick ice north of Greenland and Canada. It takes a given time (several years) until the thick multiyear ice (ice that has not melted during the previous summer) has melted. There can therefore still be ice in one location of the Arctic, while the rest of the area is ice-free. When these big “bunks” of ice have melted, then the summer sea-ice cover is gone. Large-scale abrupt shifts in sea ice therefore cannot occur in summer.

Winter sea ice, however, forms very homogeneously over the whole Arctic basin, when the ocean reaches the freezing temperature (the ocean temperature is relatively homogeneous over the basin). Warmer conditions in winter inhibit the growth of multiyear ice but a thin cover will always form on top of the ocean if the water is cold enough even if the ice melted in summer. Therefore, the sea-ice thickness and sea-ice volume decrease whereas the sea-ice area stays relatively constant and can still cover large areas (where the ocean is cold enough for ice to form). When the ocean does not reach the freezing temperature in winter, a large area of sea ice does not form any more and the sea-ice area declines abruptly.

What is the take-home message?

The explanation for the different behaviours in the retreat of summer and winter sea-ice is quite simple: the summer sea-ice cover disappears when all summer sea-ice has melted. The winter sea-ice cover disappears when no new ice forms in winter. As ice formation and ice melting are different processes governed by different mechanisms, the behaviour of the ice decline is different in both cases.

Note: These results are only relevant for the Arctic sea-ice cover as the Antarctic sea-ice cover is governed by different processes.

Further Reading

Acknowledgement: Thanks a lot to Sebastian Bathiany, who took the time to make sure I understood his paper well and helped me to make this blog entry understandable 🙂

Edited by Emma Smith and Sophie Berger

 

 

Image of The Week – The Ice Your Eyes Can’t See!

Image of The Week – The Ice Your Eyes Can’t See!

Ice sheets and glaciers are very visible and much photographed (e.g. hereelements of the Cryosphere but what about the vast, invisible and buried parts?  Around a quarter of the land in the Northern hemisphere remains frozen year round, making up a hugely important part of the cryosphere known as permafrost. Permafrost largely exists at high latitudes (e.g. Siberia and the Canadian Arctic) and these areas store a huge amount of carbon, around twice as much as currently exists in the atmosphere. As the global climate warms these frozen areas of ground begin to thaw (Figure 2) and the trapped carbon is released into the atmosphere in the form of CO2 and methane – both greenhouse gases.

Figure 2: Permafrost thaw ponds in Hudson Bay Canada (taken from Wikimedia )

Figure 2: Permafrost thaw ponds in Hudson Bay Canada (taken from Wikimedia )

In order to better understand how and when this carbon will be released computer models known as land surface models (LSMs) are used. The estimates of carbon emissions produced by different LSMs vary greatly and many of the models are not yet able to accurately re-produce present day measured soil carbon levels well. A new study by Jafarov and Schaefer (2016), published last month in The Cryosphere, has improved the way frozen organic carbon is represented and simulated in the SiBCASA LSM, producing a simulated present-day soil carbon map (Figure 1) which is much closer to the known soil carbon map of the Northern Hemisphere (NCSCDv2). Both the spatial distribution of carbon and the total amount of simulated permafrost carbon (∼560 Gt C, much closer to the observed value ∼550 Gt C) is improved.

This is a step closer to better understanding permafrost carbon release and the factors that effect it. The authors of this study found they were able to make these improvement to the SiBCASA LSM by improving  simulated thermal dynamics of the soil, improving soil carbon dynamics and initializing the model using NCSCDv2 data.

To find out more check out the full article and remember, it’s not just the ice your eyes can see that is important!

Edited by Sophie Berger and Nanna Karlsson

 

 

 

 

Karthaus Summer School 2015

Karthaus Summer School 2015

After a train, the London Underground, another train, a flight, three more trains and a taxi (shared with people I had met on my way); I had arrived in a small Alpine village in the very north of Italy.

The cross on Kreuz Spitze. (Credit: I. Nias)

The cross on Kreuz Spitze. (Credit: I. Nias)

The reason for this rather convoluted journey?

To attend the Karthaus Summer School on ice sheets and glaciers in the climate system. I’m pleased to say it was definitely worth the trip getting there!

Nearly every September for the last 20 years, around 35 glaciology students from all around the globe descend on the village of Karthaus for 10 days to learn about all things icy. This year we were a mixture of mostly PhD students, a few postdocs and masters students. We were joined by 11 scientists from institutions around Europe, who were willing to give up some of their valuable research time to lecture students in their area of expertise (maybe the food and wine is enough to persuade them…).

Working…

Each morning we had lectures on a range of topics, including continuum mechanics, ice dynamics, numerical modelling, geophysical methods, polar oceanography and climatology; with plenty of coffee breaks in between to keep us alert. The lectures were excellent – I felt that in each topic, the basics were explained in a good amount of detail, enabling us to get a grasp on more complex ideas. I’m sure I will be referring to the lecture material in years to come. In the afternoon (after the three course lunch!) we went on to problem exercises, which we tended to work on in pairs, and group project work. These group projects were a great way to get stuck into a particular problem in more detail, in an area of glaciology that was not directly related to our own research.

The results of our group projects were presented on the last afternoon. It was great to hear what everyone had been working on: from reconstructing glacial history of the Tibetan Plateau to modelling ice on Mars.

… and playing

It wasn’t all work – each evening there was plenty of time before dinner to go for a run, play ping pong, sleep, or sauna. With the exception of perhaps the penultimate evening, when the time was spent making our group project presentations. And there was plenty of post dinner socialising, which mostly involved playing games in the bar.

Making the most of the good weather on our afternoon off. (Credit: I. Nias)

Making the most of the good weather on our afternoon off. (Credit: I. Nias)

Before I attended Karthaus, there were a number of things previous participants told me about. When I told people I had a place, the most common response was “enjoy the food!”. Despite this, I don’t think I quite appreciated what it was going to be like to eat a three course lunch and a five course dinner every day! It was absolutely delicious though – fresh salad, homemade pasta, and lots of cream and parmesan. And of course bottles of the local wine on every table.

Another thing I was forewarned about was the yearly tango lessons from Hilmar Gudmundsson. I say “warned” because, as someone with zero sense of rhythm, dancing is not a skill I possess. Luckily, I didn’t seem to be alone in finding it a challenge, and seeing as the woman is supposed to “follow” the man, it wasn’t actually my fault when it went wrong (apart from when I got told off for trying to take the lead!). It was great fun and people got very much into it – so much so that we had a couple more dance nights, where we were also taught some German disco fox and Scottish ceilidh!

Excursion – to Hollywood!

Outdoor screening of Everest in the village square. (Credit: I. Nias)

Outdoor screening of Everest in the village square. (Credit: I. Nias)

Something that was definitely not expected was the public premier of the movie “Everest” in the village square, a week before it was released to cinemas. It turns out that much of the movie had been filmed in the surrounding mountains and on the glacier we visited on our excursion. This free public viewing was in honour of the help and hospitably the crew received during the filming. They must have done an excellent job in turning the Alps into the Himalayas.

When we took the cable car up to the Hochjochferner glacier the following Wednesday for our excursion, the cloud was so low that for all we knew there could have been Everest looming over us. Lack of snow cover on the ice meant we were unable to walk to the weather station that Carleen Tijm-Reijmer described in her lecture. However, we were still able to get up close (and underneath) the glacier. We had the chance to spot some of the geomorphological features we had learnt about in Arjen Stroeven’s lectures. When you see a large boulder suspended in the basal ice, it is easy to understand how striae are scratched into the underlying bedrock. After an early lunch in a mountain hut (including wine), we were free to go on a hike in the surrounding mountains. My group walked to a rock glacier in a neighbouring valley – the weather made the place feel more like Wales than the Alps, so we warmed ourselves with a Bombardino in another mountain hut.

Excursion to the Hochjochferner Glacier (left). Getting a closer look of the glacier (right). (Credit : I. Nias)

Excursion to the Hochjochferner Glacier (left). Getting a closer look of the glacier (right). (Credit : I. Nias)

On the last evening, after the five course meal, we were treated to live music by members of the group. We then moved to the village hall for a final night of Karthaus dancing. It was a great evening to end a fantastic 10 days, and the next morning saw all of us (tired and slightly worse for wear) making our way home.

 Frank, Carlo and Hans performing on the last night. (Credit: I. Nias)

Frank, Carlo and Hans performing on the last night. (Credit: I. Nias)

I highly recommend that anyone who is beginning their career in glaciology applies next year. A huge thank you to Hans Oerlemanns and all the lecturers for creating such a fantastic summer school. Also thanks must go to Paul and Stefanie Grüner and all their staff at the Hotel Goldene Rose for making us feel so welcome!

Edited by Sophie Berger and Nanna Karlsson


Isabel Nias is a PhD student at the Bristol Glaciology Centre, University of Bristol, supervised by Tony Payne. She is using an ice-flow model to investigate grounding-line dynamics of ice streams in the Amundsen Sea Embayment, and how this may impact future sea level. Her work is part of the UK Natural Environment Research Council iSTAR programme, which aims to improve understanding of the stability of the West Antarctic Ice Sheet.