All posts by Anne Le Brocq

“Huge Antarctic iceberg poised to break away”

One of the reasons I was motivated to make Ice Flows was to help people understand iceberg calving (breaking off) behaviour: sometimes iceberg calving is a normal part of the life cycle of a glacier which ends in the sea – snow feeds the glacier, which is turned into ice, which is then lost further down the glacier, as melting, or as icebergs breaking off the ice front.  On the other hand, sometimes an iceberg calving event is a sign that all is not well for the ice shelf.

As long as the amount of snow going in is the same as the amount lost through melting and calving, the glacier front stays in more or less the same place.  Sometimes icebergs are small, sometimes they are absolutely massive, like the one about to break off the Larsen C Ice Shelf, described in the story by the BBC:

What we need to assess is whether this iceberg is just part of the life cycle of this part of the Antarctic Ice Sheet – is it just that this part of the ice shelf has been hanging on for a while, so it is bigger than your usual iceberg, or is a sign of things to come for this ice shelf, leading to a potential collapse of the ice shelf.

Adrian Luckman, leading the project reported in the story, indicates that there is uncertainty over the implications of this iceberg for the future of the ice shelf.

To fully assess the implications, we need to use computer models that can represent the important aspects of the ice sheet/ice shelf/ocean system, and do some experiments with these models to see what might happen after this iceberg calves.

A study by Johannes Fürst published last year in Nature Climate Change1 assessed the areas of ice shelves which were important for “holding back” (buttressing) the grounded (not floating) parts of the ice sheet.  The study found that most of the ice in the part of the ice shelf about to break off was “passive” ice, i.e. that if it broke off, it wouldn’t lead to a speed up of the grounded ice behind it.  However, they noted that the ice shelf front would then take on a shape which was similar to that of other parts of the Larsen Ice Shelf before they collapsed.

Members of the Project MIDAS team published some modelling results in the Cryosphere in 20152 (open access) which suggested the rift presents a considerable risk to the stability of the Larsen C Ice Shelf.

If this iceberg calving event does lead to the collapse of the rest of the ice shelf – which is holding back the grounded ice behind it – then speed-up of the grounded ice would be likely to occur and this would then lead to sea level rise.  However, if ice shelf collapse does not occur, the ice will flow forward as normal and the ice front will most likely advance again until the next calving event occurs.

For more information on how ice sheets, ice shelves and icebergs behave, take a look at:

Project MIDAS

1Fürst, J.J., Durand, G., Gillet-Chaulet, F., Tavard, L., Rankl, M., Braun, M. and Gagliardini, O., 2016. The safety band of Antarctic ice shelves. Nature Climate Change, 6(5), pp.479-482.

2Jansen, D., Luckman, A. J., Cook, A., Bevan, S., Kulessa, B., Hubbard, B., and Holland, P. R., 2015. Brief Communication: Newly developing rift in Larsen C Ice Shelf presents significant risk to stability, The Cryosphere, 9, 1223-1227, doi:10.5194/tc-9-1223-2015.

(Edited 09/01/17)

Ice Flows screen capture videos

I’ve recorded some screen capture videos for use in talks to demonstrate ice sheet behaviour.  I found it hard to demonstrate and narrate at the same time when I tried using the tutorial in a presentation!

The videos are on YouTube, but if you want the .mp4 file, you can also download them from the links provided below:

Demo level of Institute Ice Stream:


(mp4 file: (16 MB))

Demo level of Mass Balance of an ice sheet:

Narrative: To introduce the role of snowfall and ocean temperature changes in controlling the extent of a marine ice sheet.


(mp4 file: (13 MB))

Demo level of Calving Front Change:

Narrative: That icebergs are a normal part of marine ice sheet behaviour – that it is important to look at the net change in the calving front location to understand the implications of an iceberg calving event.


(mp4 file: (10 MB))

Demo level of Marine Ice Sheet Instability:

Narrative: On a forward slope, a small change in ocean temperature causes a small change in the groundling line location.  However, a small change on the threshold of a reverse slope means a large grounding line change.  The level starts with the Institute Ice Stream grounding line in approximately its present position.


(mp4 file: (17 MB))

Demo level of Filchner-Ronne Ice Shelf Collapse:

Narrative: Demo of how increased water temperatures beneath the Filchner-Ronne Ice Shelf could cause the collapse of the ice shelf and retreat of the ice sheet.  The level starts with the Institute Ice Stream grounding line in approximately its present position.


(mp4 file: (5 MB))

Reflecting on media coverage of Ice Flows

Ice Flows got a bit of media coverage after its launch last week, which really helped to raise awareness of the game, such that the website has had hits from all parts of the globe.  On the whole it has been good, with some very positive reviews, but there have been a few things that I have been reflecting on.

The aim of creating the game was to help people understand how ice sheets work, and how they respond to changes in the environment.  As I said in the Times Higher Education article, iceberg calving events are a good example of something that is often misinterpreted and misrepresented in the media and people’s understanding.  The “case of the 150 000 dead penguins” was also a good illustration of how a scientific study can end up being misreported.  I use this as an example on the “Science vs Fiction” section of the website, in fact, it is partly what drove me to develop that page.

I was therefore, amazed when I scrolled down the article to find that they had signed off the article with two references to Antarctic related stories, one of which was the first Guardian article about the 150 000 dead penguins.   The other was about a NASA study indicating that Antarctica was in fact gaining mass, not losing it, a study that is viewed as an outlier and to have some problems with the analysis.  Many people would have read this article about the game (great), but would have been presented with two widely questioned statements about Antarctica, almost as “fact” (not so great).

Another reason for creating the Science vs Fiction page relates to when I showed an early prototype version to a colleague; I was concerned by his tongue-in-cheek response that “oh, so what you’re saying is climate change is good for penguins because they can get to the fish under the ice shelf”?  So, I made dragon-penguins and dinosaur-penguins to help indicate that the biology in the game is not accurately represented.  Still, an article is headlined: “Game shows how things could play out for Antarctica’s penguins“.

Lastly, to my amusement, the Times Higher article miscopied from the press release at the end, talking about the project funding the work, converting the text “modelling of ice flow”, to “modelling of ice floes”…  Maybe my clever title wasn’t so clever.

Without the media coverage, the game would not have reached anywhere near as many people as it has, and like I say above, on the whole the coverage has been very positive.  The motivation for the game was to increase people’s understanding of a complex system, that we as scientists are also still working to understand, so they are able to see past headlines and assess the story for themselves – including the complexity and uncertainty behind the story.  Science is rarely black and white, unlike headlines…

Ice Flows is Go!

Ice Flows is launching today at the SCAR Open Science Conference in Kuala Lumpur!  Come and find me at my poster, 2pm-3.30pm in the “Antarctic education, outreach and training” session, or…

…you can play it at: or download it from the App Store & Google Play store.


Please get in touch if you would like to discuss adding further processes, regions, translations and any other ideas for development!

Full version of Ice Flows coming soon!

Thing have been a bit quiet on the blog since we released an Alpha test version of Ice Flows, that’s because we’ve been working hard on putting everything together for the full version. The good news is that we are very close to a finished version, we are just putting the finishing touches, making sure everything looks as it should.

Steph Cornford has written more about developing the ice flow model here:

Ice sheet modelling and education by stealth

and here is a sneaky peak of some of the characters we’ve been working on!


We will be carrying out some testing on this final version, then the plan is to release the game on the web and in the app stores at the time of the SCAR Open Science Conference in Kuala Lumpur in August.

In the meantime, you can play the Alpha Test version

Ice flows – but how, exactly?

by Steph Cornford

In response to some discussion generated on the cryolist email list about the ice flow formulation, we have put together a brief commentary on the ice flow formulation.

You can play the Alpha Test version at:

‘Ice flows’ is an educational game aimed at school-aged children, which means that we had to think about some potentially conflicting objectives. We wanted children to learn some lessons (perhaps guided by their teachers) about ice flow, and Antarctic ice flow  in particular, that reflected contemporary scientific understanding, so we had to make some decisions about the appropriate lessons to learn. At the same time, 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.

We want children to understand that ice sheets are dynamic environments, and that processes like iceberg calving and melting near the margins are always taking place. We want them to understand that if the accumulation of ice in the interior matches losses at the margin then an ice sheet will hold its shape, and that a change in either of these processes (and perhaps others, such as bed slipperiness) results in a change of shape.  We need to show ice contacting submarine beds where it is thick enough, and floating on water where it is not. We’ll be delighted if older children can see that flow speeds up toward the margin and that mass is conserved –  that downstream acceleration results in both horizontal stretching and vertical thinning. And, because it is an idea that has been so important in recent thinking, we want to include marine ice sheet instability.

There are a few things that we were confident could be left for university or later. Glen’s flow law, the Stokes equation, numerical solution of non-linear boundary value problems – these are all things that are important to glaciologists, but they would slow down the calculations, and omitting them does not preclude the broad understanding outlined above. They would also have made for a longer and more expensive period of  development  –  they are not the kind of calculations that game development tools are designed to support, or indeed, that game developers are necessarily familiar with.

In the end, we constructed a much simplified ice sheet model that relied only on the simplest kind of calculations. The ice sheet is built up from a queue of rectangular ice blocks, which move from left to right on the screen. We’ll turn to the velocity calculation below, but for now we need only remember that it is always positive and increases from left to right smoothly. At every time-step the left and right edges of each ice block  are moved according to the velocity field, which results in each block stretching (as the right edge is moving faster than the left).  The height of the ice block is reduced to keep its area constant, and then reduced further if there is any ice-shelf melting to account for. After that, any ice blocks right of the screen edge are removed, and, if there is space at the left hand side of the screen, a new ice block, whose height is determined by the accumulation, is added. In other words, we implemented a simple Lagrangian scheme for mass transport.

The velocity field is re-computed at every time-step from the ice sheet shape to follow a simple curve, starting from a chosen speed at the left edge of the screen and accelerating to reach a value computed from something like the famous Schoof 2007 expression – depending on thickness, buttressing, and rheology – at the grounding line. The strain-rate also varies from left to right, from zero at the left edge, to values derived from the calving front boundary condition beyond the grounding line. Obviously, this is a very crude approximation, but it contains the ideas we want to get across: acceleration toward the margin, the importance of buttressing, and even marine ice sheet instability.

At which point, it’s over to the real game developers to make something that children actually enjoy.

Try out our alpha test version!

We are pleased to announce that we have an “Alpha” test version of the game available here for testing and feedback.  Note that “Alpha” is the test version that comes before “Beta”, the test version which comes before the final launch, so it is not a finished product!  Please bear this in mind, and check out for screen shots of the game screens.

Some elements of the graphics also needs polishing, so please bear with us while we are still working on these aspects.

The demo is set up for the Institute Ice Stream, but the game will have different unlockable levels for different ice streams.  At the moment, we are only working on Weddell Sea ice streams as the game development is being funded by a NERC grant led by Hugh Corr at BAS, looking at the ice streams draining into the Filchner Ice Shelf.

Try out the game at:

(best using Firefox, and not yet supported on mobile platforms. The test version is being temporarily hosted by the developers whilst we put together the website)

What you need to know before you play:

The left hand slider is the input rate (snowfall) control and the right hand slider is the ocean temperature control.  These may be a cloud which changes size, and a thermometer in the final version.

There will be fish in the ocean beneath the ice shelf which will be the “collectibles”, we haven’t put them into this version as we are still perfecting this part of the game…

What else will there be in the full game?

– Training levels and an intro tutorial which explains how the ice sheet works

– “Tutorial mode” with the game play elements stripped out, which can be used for explaining ice sheet behaviour

– A quiz about ice sheets to gain extra points

– A penguin store where you can spend your points upgrading your penguin!

– A website explaining the science behind the game, comparing “Science vs Fiction” in the game

Leave a comment or email me to provide any feedback!