Is it time for a change..?

My employer DMI, and specifically my team at the National Centre for Climate Research are recruiting.

Not an earth-shattering revelation perhaps but these are premium research jobs, and this is probably a once in a generation opportunity in Denmark.

Let me explain. They are full time and permanent positions, working right at the cutting edge of both basic climate research, and importantly, climate services. You can see the full adverts at the links below:

DMI scientists collaborating with local hunters in the field in Greenland

I call these positions once in a generation positions because these kind of positions just don’t come up very often. Part of the reason these are now available is related to the generation change* that is coming to DMI. Right now we are fortunate also to have a number of large EU funded projects as well as danish funding for our Climate Atlas and new hydrology department which is giving us the opportunity to plan for the long term.

Sea level rise is an existential threat for Denmark, at least in the long term and we are putting a great deal of effort not just into the science of melting ice, tipping points and so forth to try and assess the potential risks, but also into planning climate adaptation and mitigation in the short and medium term.

The new positions related to climate and ice sheets and sea level rise will have some flexibility with them in terms of how the jobs evolve and research directions. There will certainly be opportunities for whoever is hired to steer in their own direction and initiate their own research programmes within the broad frame of the topics. I can certainly also only praise the management for the generally supportive and research positive encouragement.

I’d like to help cast the net wide and deep to get as strong a pool of candidates as possible, so please do feel free to get in touch with me either here or via the usual email, and other social media feeds if I can help at all. And if you have good students, postdocs or others, please do share.

We will be holding some “open house” events where you can come in person to visit DMI or sign on in a virtual event to hear more about the positions, about DMI and what it’s like to work in Denmark. Again get in touch to hear more about those.

*”Generations skift” in Danish – I have not looked at the statistics but I suspect many public institutes, including weather and climate services are greying. There was an expansion during the 80s and 90s as numerical techniques became more widespread and integrated into weather prediction and by extension climate – many of the staff employed then are getting close to retirement. In my view DMI is wise to start trying to replace these staff now so there will be continuity and knowledge exchange before it becomes a problem.

Oh Vienna…

In the before times I would usually spend this week walking around a world class city humming an old 80’s hit (- don’t ask me why it was so durable in my head, probably something to do with being an impressionable age at a time when access to pop music meant half an hour on a Thursday evening).

Anyway, it is the time for EGU… Sadly I will not be wandering the streets of the ever beautiful (and most livable) capital of Austria this year. I have to get some actual work done, but I’m following the #EGU23 on mastodon and hoping to catch a few highlights on the sides. I do have a poster, which will be capably presented by PolarRES PI Priscilla Mooney and my DMI Colleague Abraham Torres on Thursday.

The topic is our PolarRES project – an ambitious Horizon 2020 effort to produce a large ensemble of regional climate simulations over both poles. These are state-of-the-art regional climate models run at unprecedented high spatial resolution and all data will be made open access and free via the CORDEX project.

I will also put it here later – feel free to comment here or ask questions on mastodon or get in touch by email if it sounds exciting.

Mottram, R., Mooney, P., and Torres, J. A. and the PolarRES Consortium: A first look at the new PolarRES ensemble of polar regional climate model storylines to 2100, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-14470,, 2023.

Other posters and talks I’ve contributed to from PolarRES are

Kristiina Verro’s talk on HCLIM_Arome results from the Antarctic peninsula:

Verro, K., van de Berg, W. J., Orr, A., Landgren, O., and van Ulft, B.: New non-hydrostatic polar regional climate model HCLIM-AROME: analysis of the föhn event on 27 January 2011 over the Larsen C Ice Shelf, Antarctic Peninsula, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-13864,, 2023.

Abraham Torres joined our group last year and is primarily working on PolarRES also. He will show some of our preliminary HCLIM results for both the Arctic and the Antarctic

Torres-Alavez, A., Landgren, O., Boberg, F., Christensen, O. B., Mottram, R., Olesen, M., Van Ulft, B., Verro, K., and Batrak, Y.: Assessing Performance of a new High Resolution polar regional climate model with remote sensing and in-situ observations: HCLIM in the Arctic and Antarctica, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-14090,, 2023

Quentin Glaude is a collaborator from Liege in the Horizon 2020 PROTECT project on sea level rise contributions from the cryosphere . Baptiste Vandecrux, a former PhD student with me here and now working at GEUS is also presenting some work based on the same models as Quentin, with a comparison to the PROMICE observation statons on the Greealnd ice sheet. It’s very cool application of machine learning and the results are very interesting.

Glaude, Q., Noel, B., Olesen, M., Boberg, F., van den Broeke, M., Mottram, R., and Fettweis, X.: The Divergent Futures of Greenland Surface Mass Balance Estimates from Different Regional Climate Models, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-7920,, 2023

Vandecrux, B., Fausto, R. S., Box, J. E., Covi, F., Hock, R., Rennermalm, A., Heilig, A., Abermann, J., Van As, D., Løkkegaard, A., Fettweis, X., Smeets, P. C. J. P., Kuipers Munneke, P., Van Den Broeke, M., Brils, M., Langen, P. L., Mottram, R., and Ahlstrøm, A. P.: Historical snow and ice temperature compilation documents the recent warming of the Greenland ice sheet, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-9080,, 2023.

Nicolaj Hansen (who finished his PhD with me and Sebastian Simonsen at DTU Space last year) has just submitted a beauty of a paper which he will talk about – also partof PROTECT.

 Hansen, N., Sørensen, L. S., Spada, G., Melini, D., Forsberg, R., Mottram, R., and Simonsen, S. B.: ICESat-2 Ice Sheet Mass balance: Going below the surface, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-12349,, 2023

Mathias Larsen is a current Phd student with me and is presenting a poster on the CARRA dataset and an application in surface mass balance modelling. This work falls under the danish National center for klima forskning

Larsen, M., H. Mottram, R., and L. Langen, P.: CARRA-driven simulation of Greenland Ice Sheet surface mass balance at 2.5 km resolution, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-5852,, 2023

Last year I co-organised a bootcamp for early career researchers on Arctic processes in the CMIP6 models. It was super fun and would not have been possible without the support offered by Anne Fouilloux, Tina Odaka and colleagues from the Pangeo project. Their poster is super interesting and if you’re interested in optimising the use of big climate data, go and check it out!

Fouilloux, A., Marasco, P. L., Odaka, T., Mottram, R., Zieger, P., Schulz, M., Coca-Castro, A., Iaquinta, J., and Eynard Bontemps, G.: Pangeo framework for training: experience with FOSS4G, the CLIVAR bootcamp and the eScience course, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-8756,, 2023.

Excitingly, at least 3 of the projects at the bootcamp will also be presented at EGU this year. So, lots to be getting on with, for now, here’s a link to Ultravox’s finest…

Q is for Qaanaaq

Back in Denmark after 2 weeks in Greenland. Always a bit strange to come back, not just that transition from Arctic cold to European Spring but the sheer abundance of the fertile mid-latitudes, colours, plants, trees, the sheer number of people.

Not to mention that expedition frame of mind, where you are really focused on accomplishing a given set of often quite complex tasks (almost) without distraction. It is the ultimate deep work task, and naturally readjusting to family life, not to mention the tsunami of work tasks left on hold is… difficult.

This particular deep fieldwork has been carried out in Qaanaaq, Northern Greenland, as I’ve written about before. The community of about 600 people (and maybe a 1000 dogs), was established in the 1950s when the US established the Thule air base. It is almost the most northern settlement in Greenland – and certainly the largest. The small village of Siorapaluk is about 45km (or 6 hours by dog sled) further away.

The town was formerly a summer hunting spot, but after Thule was decided on, the community was moved to Qaanaaq year round. It has an association with the famous Danish explorer Knud Rasmussen, whose old house is a museum (allegedly. I’ve never actually had time to visit it..)

DMI established a geomagnetic observatory there in the 1950s and today its part of the Comprehensive Test Ban Treaty Organisation network that DMI operates on behalf of the Danish government from what we now call the DMI geophysical facility. There is transnational access to this via the INTERACT network.

This year we again visited the glaciers at the head of the Inglefield Fjord – expanding a new research programme we piloted last year. We also did a lot of work on the sea ice – not just Steffen Olsen‘s ocean programme, but a new NCKF research programme looking at biological productivity and carbon cycling in the fjord, led by Anna Pedersen, a DMI PhD student also at the University of Southern Denmark. I and another colleagues also did a lot of work on snow processes that is something of a pilot programme for a processes project we’d like to establish next year that will also involve (hopefully) our weather forecasting colleagues and perhaps also the GEUS PROMICE programme.

All of this work involved 6 days of travelling over and camping on the sea ice, plus an additional day trip. We were lucky with the weather, although it was *extremely* cold, around -25 to -28C most days, and dipping well below -30C at night (though being after the equinox it was never truly pitch dark). However, in general there was little wind, no fresh snow (which can really slow the dogs down as they struggle to pull through deep soft snow) and the sun shone every day. This meant we basically managed to achieve the full planned programme – including our extra-optimistic goals – which almost never happens in fieldwork.

Camping on the sea ice at sunset. Northern Greenland
This work by Ruth Mottram is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.

I intend to write a whole series of posts based on what we have been doing scientifically and technically as well as some general observations. There have been various hints already in my preferred social network. The whole trip was super inspiring, it’s always valuable to get out and observe the real world when you’re trying to model it, understand it and make projections of sea level rise.

I also promised to make another Lego scientists series and took quite a few photos in between times to do so. However, the research programme was packed, so I had no time at all to make the comic during fieldwork, that will have to wait a few weeks.

Expect my pixelfed account to host gratuitous numbers of dog pictures. And ice pictures. And unexpectedly clear blue skies. For now it’s time to unpack, get the washing machine going and spend some time with my family.

Sunset over sea ice near Qaanaaq, North West Greenland
This work by Ruth Mottram is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.

As ever, thanks to my amazing colleagues Steffen Malskær Olsen, Andrea Gierisch and Anna Pedersen for an incredible trip and to DMI station manager in Qaanaaq Aksel Ascanius without whom most of this work would be impossible.

Special thanks to our friends in Qaanaaq, the local hunters, whose unfailing energies and knowledge are absolutely essential to these scientific projects. We literally could not do this without them and of course their dogs.

I must also credit DMI and the Danish Government for funding via the National Center for Klima Forskning and thanks also to Horizon Europe projects PROTECT on sea level rise and PolarRES for additional inspiration and funding and to my colleagues at the Horizon Europe/NERC project OCEAN:ICE for indulging my two weeks away. All three projects will benefit from the insights gained in this fieldwork.

Signs of Spring

Currently, I’m very busy getting ready with colleagues to travel to Greenland next week. We have an extremely full programme of fieldwork activities covering oceanography, biology, sea ice, snow and glacier processes as part of our NCKF work. More on these no doubt in a future post…

Yesterday, one of my ace DMI colleagues (without whom most of the work we plan would definitely not happen) shared the first optical satellite image of the area this year – taken by ESA’s Sentinel 2 (a truly astonishing source of free imagery and everone should know about it). Because the area is very far north, it has been in the Polar night until now so we have been reliant on the ESA Sentinel 1 imagery based on radar.

First Sentinel-2 optical satellite image of the year downloaded from Sentinel Hub’s EO Browser today. Processing with Sentinel Hubs optimised natural colour filter has introduced some artefacts, notable the brigh white patches which probably represent areas of shadow due to the low solar angle. The area is blanketed in thin cloud and only parts of the glaciers, sea ice and icebergs are clearly visibe.

It’s a wonderful thing to see the first satellite image of Spring, akin to other signs like the first cuckoo (in the UK), the first peewit egg (in the Netherlands), and the timing of the cherry blossom in Kyoto.

The first lapwing (peewit) egg of the year was traditionally presented to the Dutch monarch – these days, given the

There was recently a very illuminating thread on phenology on mastodon in reply to a query by Pauline von Hellerman where the Diagram Monkey John Kennedy pointed out the existence of the Pan European Phenology network – not something I was aware of before (though I’d suspected it’s existence) – and who have all sorts of interesting data.

Where biology is clearly showing us earlier springs due to climate change, the date of the first optical image is unlikely to change any time soon due to climate change.

A newer updated version of the Economist’s cherry blossom flowering date plot provided by Datagraver after I posted the old one. See:

Nor are species assemblages (it’s not quite certain that it’s the same variety of cherry blossom for the whole 1200 year period), or biodiversity losses (the cuckoo is down 65% since the early 1980s alone in the UK, and heaven knows it was not particularly common then) likely to affect it. Not to mention human behaviour changes, the lapwing has gone from being a common agricultural bird to near threatened over the same period, which probably also affects the reliability of that data.

Of course, quite a bit of what you might call bulk phenology can be done by satellite too now…

Copernicus land dataset showing biological activity in Europe basedon satellite data available here

As for Qaanaaq, there is not much in the way of biological phenology, but a compilation and analysis of data on sea ice cover and thickness over the last 60 years would probably be as instructive. Do get in touch if you’re interested in doing this as a student project…

Out and about in Leeds..

I’ve been on holiday this last week and I’m combining the trip to the UK with a visit to colleagues and collaborators at the University of Leeds. I’ve also been nabbed while I’m in Leeds to give a wider interest talk at the Royal Meteorological Society Yorkshire branch in Leeds.

I’ll be discussing ice sheets, their contribution to sea level rise and how the future is looking. There may also be some nice photos from our fieldwork in Northern Greenland for those who like dogs, icebergs and snow…

If you’re in Leeds and fancy joining you’re most welcome to register and attend at this link.

In general, I’m trying to reduce my travel this year, last year, with all the rolled over meetings from the COVID times was disruptively busy with work travel, it makes it challenging to actually get the work done. So I think combining work and holidays and rolling up meetings into a block is the way forward.

Although I very much appreciate the opportunity to present online at various meetings, I’m less convinced about hybrid meetings where the purpose is mostly scientific discussions, that is something that works much better either all online or all in person in my opinion, but I think they work well when the aim is to present new and ongoing work (like EGU).

For those who are interested but can’t attend I will see if the talk tomorrow will be recorded and can be uploaded somewhere. Here’s the abstract:

Frozen Threats: Understanding the Role of Ice Sheets in Sea Level Rise

In this talk, we will delve into the world’s ice sheets and explore their importance in the climate system. Ice sheets are the largest stores of freshwater on the planet, their size and location means they influence our climate but their interactions with the atmosphere and ocean are complex. As the world warms, they will inevitable have an impact on sea level. Adapting to sea level rise will be one of our civilisations biggest and longest challenges, so understanding ice sheets is now of critical importance. They are also beautiful and fascinating environments in their own right. In this talk I will discuss some of the scientific challenges, but also show how far we have come in understanding ice sheets and glaciers.

The Inughuit cliffs near Qaanaaq in Northern Greenland rising up above the sea ice. In the far distance a dog-sled is a small black speck.

Rules of thumb about ice sheets and sea level rise:

One of the advantages of being part of a research institute are the fascinating conversations that happen over lunch between colleagues working in different areas. Today was a classic with conversation ranging from the stratospheric effects of the Hunga-Tonga eruption to the different types of snow crystals that form in snow packs and their impacts on sea ice. However, the conversation started with a request to me for some rules of thumb on sea level rise, so here they are: 

The Greenland ice sheet loses on average around 250 to 280 Gigatonnes of ice each year – that’s from all processes including melt and surface runoff, iceberg calving, basal melting and submarine melting.

It varies a bit from year to year but over the last 26 years the ice sheet has either lost ice or been neutral (and it’s had very few neutral mass budget years).

Change in mass of the Greenland ice sheet from the GRACE and GRACE-FO satellites since 2022

The Antarctic ice sheet loses on average about 100 Gigatonnes of ice net each year (probably) from all processes, it receives about 2000 to 2500 Gigatonnes of snow (depending a bit on where you measure Antarctica to end) whereas Greenland receives around ~700 gigatonnes of snow.

The small glaciers and ice caps around the world contribute a bit more to sea level rise in total each year than each of the big ice sheets currently, but they will be quickly exhausted. As there are thousands of small glaciers, most of which are not well monitored, we have to estimate how these are changing using models. It appears that on avergae they add around 0.7 to 1 mm of global sea level rise each year.

Glacier changes are not well measured at most glaciers but this analysis from Copernicus is based on a few that are in Europe.

The thermal expansion of the oceans is still the largest part of currently observed sea level rise but on an annual basis, the cryosphere now often contributes more.

As I’ve elaborated on before, 1 Gigatonne of water is hard to visualise, it is a cube 1 km long, 1 km wide and 1 km high and about 360 Gigatonnes (or km3) raise global average sea level by 1 mm, so Greenland contributes around a half to three quarters of a millimetre to global sea level every year. My old friend Lindsey Nicholson at Innsbruck University has a cool blog (which you should check out here) and shows this visualisation if it helps..

What a gigatonne looks like, visualisation shared by Dr Alex Gardner, JPL from this talk on glaciers and sea level rise

Since the early 1990s sea level rises about 3mm every year, but over the last 5 years it has been closer to 4.5mm per year. The curve over the last 2 decades has followed a quadratic shape rather than a linear shape – put simply, this means sea level is accelerating. The sea rose 10mm from January 2020 to August 2021.

Global mean sea level rise since the early 1990’s as shown in the WMO state of the climate report 2022

An El Nino, which some are warning could occur this year, may cause a temporary pause or at least slow down in sea level rise, even as global air temperatures increase, mostly due to the large amounts of rain that are associated with it, but this will only be temporary.

While the rate (3-4 mm per year) doesn’t sound like very much, every mm counts, increasing the risk of coastal flooding and storm surges affecting coastal communities.

Finally, global sea level rise is not distributed evenly, broadly speaking, the further away from an ice mass you are, the more likely it is to affect your local sea level, so Greenland matters less than Antarctica in Northern Europe.

NOAA’s visualisation of observed sea level rise from satellites in the background and at tide gauge locations (the round dots) since 1993, note the uneven pattern which reflects processes like ocean currents, atmospheric circulation and winds, local relative land movements and gravitational changes due to changing ice masses.

I hope these little rules of thumb help. Feel free to add more (or disagree) in the comments..

The expedition frame of mind

We will head to the field in Qaanaaq in late March with various instruments.

Update: It’s official now, I have booked my tickets, we have new instruments to deploy and a colleague and I are working on developing a new programme that we can hopefully also fit in alongside the currently planned programme. More on this at some point no doubt. The countdown has begun and I am getting into that fieldwork frame of mind.

I came across this blog post from old friend and former colleague, Karen Darke, who I’m now more or less out of touch with, unfortunately.

She is just back from her incredible Pole of Possibility expedition in Antarctica and she wrote this which I think perfectly summed up that expedition frame of mind..

It’s a really great blog post and well worth a read of the whole thing.

There are people and places I look forward to again but my soul is already grieving for expedition life, for the dualities that it brings: complexity and simplicity, space and confinement, alone-ness and together-ness, vulnerability and strength, connection and disconnection. I miss waking up huddled closely with my tent-mates and the time skiing silently in big open white-scape. I miss the detailed organisation of kit and systems and the contrasting uncertainty of every hour of every day. I miss feeling small and vulnerable as well as strong and capable. I miss the clear, invented purpose of every day.

Karen Darke, Pole of Possibility
One of those moments on a fieldwork expedition when everyone is busy, drilling holes in the ice to send down a CTD, drilling a sea ice core to measure salinity, digging snow pits, deploying instruments. My DMI colleagues Steffen Olsen and Andrea Gierisch are the ocean and sea ice scientists driving this work in close collaboration with our Greenlandis friends, you can read more about their work here: ..

Our fieldwork expeditions are maybe a bit more frenetic than the pole of possibility has been (in some ways, probably not others). We are always racing against the clock and the weather to get as much work done as possible. We probably cover less distance and there is perhaps less physical stress as the dogs do the hard work of pulling, rather than skiing with human muscles. Nonetheless, there is a constant low-level thrum of thinking, planning, checking. Even if there are also often whole hours, where not much other than travel happens and that are extremely valuable thinking time. (And how often do we get that in the modern world?)

Unlike the Antarctic, working with local people in Greenland means that we also see the landscape as a working place, not just a white desert far away and as Karen writes, how true this is:

It is harder than we anticipated to leave, but Antarctica has been a reminder that we are adaptable, resilient, purpose-seeking, capable humans. No matter how harsh our environment may be, we seem to find ways to connect, collaborate and create ways to not only survive, but to thrive.

On a slightly different note, I had momentarily similar thoughts to Karen on the problem of despoiling the landscape with toilet visits the first time I visited Qaanaaq, before realising that when travelling with 30 dogs (as the local people have always done), the problem is rather moot. But as I have written before, it’s easy to fall into the trap of pristinism in the Arctic. Our work on the Arctic environment is a reminder that it really isn’t. Even in Antarctica, environmental pollutants from lead to microplastics have been found, while the curse of overfishing is almost as visible in the Southern Ocean as in the northerly just as climate change is also taking a toll.

But finally, I also find myself fully agreeing with the last part, because although fieldwork is often cold, uncomfortable, difficult, exhausting, boring and tiresome, it’s also often fascinating, rewarding and exciting. And the experience can change us.

Just as a photograph can’t always capture the profundity of a place or a moment, it is sometimes difficult to find words that describe how something has sculpted us. An experience can impact us so deeply that we don’t immediately know how to translate it for others. And may never

I am immensely privileged to be able to do fieldwork in Greenland and I am extermely grateful for the opportunity to do so.

The vanishing of the ice…

I was recently asked to comment on this interesting new paper by David Rounce and co-authors for AP by Seth Borenstein called “Global glacier change in the 21st century: Every increase in temperature matters”. You can read his resulting summary here . I’m posting here the slightly expanded and lightly edited response I sent to Seth in response to his (very good) questions.

The authors only look at the small glaciers and ice caps in this study, not the big polar ice sheets, though they do also cover small peripheral glaciers in Greenland and Antarctica that are not part of the main ice sheets. Of course, this means that sea level rise from all the other important processes like thermal expansion and ice sheet met also have to be taken into account on top of the numbers given here.

Their main findings were that at 1.5 °C above preindustrial, we can expect total glacial mass loss between 2015 and 2100 would be 26% with 90 mm of sea level rise and 49% of the small glaciers and ice caps lost globally. The paper only deals with these small glaciers and does not count the big ice sheets!

At 4°C, we’re looking at 41% mass loss with ~154 mm of sea level rise and 83% of glaciers lost. At 2.7 °C, where the world is now heading, 32% mass loss, 115 mm of sea level rise and 68% of glaciers lost.

I’m sad to say that the results aren’t exactly a surprise – the community has known for some time that the loss of glaciers is basically linear with temperature, so the title of the paper is really spot on, every tenth of a degree really does matter. This earlier paper by my Horizon 2020 PROTECT project collaborator Ben Marzeion shows something very similar But it’s a nice new result with the latest generation of glacier model and updated with the latest CMIP (IPCC) scenarios and they included some new processes that weren’t very well accounted for in previous work.

My first thought was that these latest estimates were actually a little lower than I expected, but the baseline in the paper is 2015 – we should remember that many of these glaciers have already lost quite a lot of ice (see my two photos of Nigårdsbreen in Norway, taken only 13 years apart) – so the new estimates are basically in line with what I would have expected given earlier work. I’d also expect that they will continue to lose ice beyond 2100 so it’s definitely not an end state that they are giving here. As they state in the article there will be widespread deglaciation of some pretty iconic parts of the world, even under the present planned emissions reductions..

In many ways part of the problem has been the previous studies have not always accounted for all the processes: frontal ablation (melt and calving of vertical ice cliffs, mostly in contact with water), the effect of debris cover and so forth (the latter will likely reduce the rate of loss, the former probably increases it). Given what we know about these processes and how to represent them in models, I still consider this work to be a more realistic estimate. Then we also need to account for the climate models and the scenarios used to force them – there are some important differences between CMIP5 and CMIP6 which might also account for some of this shift.  We have actually seen something somewhat similar for the projected changes in the big ice sheets.

It’s probably important to remember though that this study still needs to make simplifications, especially when looking at so many glaciers in so many different regions, so there will always be new updates to come with improved computing power and computational techniques and better representation of processes. Having said that, I do not think the picture will substantially change in future, though I can always be proved wrong, and the glaciers community are now at the stage of refining estimates for rates of mass loss.

Globally the loss of glaciers means sea level rise. Regionally and locally the biggest consequences will be for for water resources and we’re likely to see a local increase in natural hazards like outburst floods and avalanches that will need to be carefully managed. There have been a couple of instances already in the last year or two that probably demonstrate this well (e.g. the Marmolada glacier in Italy last year).

Sea level budget divided into components, from Legeais et al. 2018 ESSD The steric component is the expansion of sea water as it warms.

The small glaciers are currently a larger contributor to sea level rise than the big ice sheets, but that will of course change as they disappear and even small amounts of sea level rise, as represented here, are important in coastal communities where storm surges can occur. So we definitely need to account for their loss in planning for sea level rise and extreme storm surges. Locally and culturally there will also need to be changes. I think this will be a little traumatic for some cultures which have always considered themselves “glaciated” nations. The response I see to pictures  of the current state of the European Alps where people are skiing on artificial snow in green fields is a case in point here. It’s a shocking thing to witness.

I include myself in the group who has to get used to the cultural shift.  I have worked on glaciers in the Alps and Norway which are really rapidly disappearing. It’s kind of devastating to see, but it’s not actually surprising. We have known it was coming and in many cases (including the authors of this paper), measured the massive losses (last year, 2022 was a disaster for the Alps and both Fabien Maussion and Matthias Huss who are co-authors on the paper are running very comprehensive programmes that show in real time how much of a disaster) and predicted it with some accuracy. But we’re now at the point where it’s really undeniable that these glaciers are going fast.

The Rhonegletscher in the timelapse above is a really iconic glacier in the Alps, I have my own favourites, mostly places I’ve worked, like Norway, Iceland and Greenland, which are all to a greater or lesser extent retreating fast now. The glaciers that people consider iconic or at least well-known tend to be accessible and depend very much where you are and they will be the glaciers we mourn over in the next decades. In the French Alps, it’s probably the Mer de Glace, in Switzerland perhaps Rhone glacier or Plaine Morte (both have monitoring programmes), in Canada perhaps the Malaspina or Athabasca glaciers. There are still (just) glaciers on Kilimanjaro and Mount Kenya, the Ruwenzoris are basically gone, as are the Papuan glaciers.

One of the longest records anywhere in the world for glacier length change is Nigårdsbreen in Norway. This plot was put together by NWE: The Norwegian Water directorate who monitor a number of glaciers

Though they show in the study that ice loss is basically linear with temperature, at some point the glaciers become so small that the remianing melt is highly non-linear. And these won’t grow back under any sensible “overshoot” scenario (never mind that we don’t really have technology to remove carbon from the atmosphere at scale). Once they’re gone, they’re basically gone forever on human timescales Finally, I’d like to add a bit of anlaysis by Ben Marzeion and co-authors , it’s possible to basically put a number on the amount of melted glacier ice each kg of CO₂ leads to.

We find that under present-day climate conditions, every emitted kg of CO2 will eventually be responsible for a glacier mass loss of 15.8 (5.9–20.5) kg. Again, since the global glacier mass is decreasing with increasing temperatures, this number is greater for lower temperatures and smaller for higher temperatures.

Marzeion et al., 2018

It’s past time to stop burning fossil fuels.


I have been meaning to write about my return to field science (after 10 years mostly working on climate models) for the last 2 years, but prompted by this beautifully written piece in the Danish Newspaper information, I decided Christmas Day was the day (it for sure beats the washing up)…

“For at forstå, hvad der er ved at ske ved kloden, rejste vi mod isens ende”
“To understand what is happening to the earth, we travelled to the end of the ice”

Martin Bahn og Anders Rye Skjoldjensen (foto) in Information 23rd December 2022

To make one thing very clear straight away, and as the newspaper article also makes very clear, my colleague Steffen Malskær Olsen has established and maintained a very long-running programme of observations in the fjord near Qaanaaq. This town in northern Greenland on the edge of a large fjord, and close to the North Water polynya has a uniquely interesting location to study and understand Arctic processes. The DMI facility there is long established and part of the INTERACT network of Arctic field stations. The 15-year record collected by Steffen is more or less unbroken and uniquely valuable. None of the science I’m planning to do or to work on would be possible without his dedication, hard work, insight and bridge building within the community in Qaanaaq. He and my other DMI colleagues involved in this programme are brilliant scientists and great field companions and I feel privileged to be able to work with them in this incredible place.

In the field: Steffen and team retrieving an oceanographic mooring with instruments on it after a winter out in the fjord in 2021.

Secondly, as the article also makes clear, scientists are not individualistic heroes who beat the odds, it’s a team sport. And it’s especially true in Greenland where the true heroes of this story are probably not scientists but the local hunters and fishers who guide and transport us and whose knowledge and experience is unmatched. I include also on this category our DMI colleague Aksel Ascanius who lives and works in Qaanaaq has been an essential part of the programme since the earliest days, as well as keeping other long-term observations in the network running in this part of the world.

Collaboration with the people who live in the Arctic has been essential for success in Arctic science since since the days of Franklin and Rae (for British readers) or Suersaq, aka Hans Hendrik, (after whom Hans Island is named) for Danes..

Anyway, back to the science of the present-day. DMI has progressively added more and more elements to the field laboratory in Qaanaaq in addition to the longer running observations. A non-exhaustive list would include an infrasound monitoring station that is part of the CTBTO, weather observations (of course), surface emissivity measurements by drone, fjord salinity, temperature and photosynthetically available radiation measurements plus snow and sea ice measurements as well as work with satellites and biology. One glaring omission, up to this year at least, was the glaciology of the region. How does the ice sheet affect the regional climate, how does the ocean affect the glaciers that calve into the fjord? Can we learn about some important but poorly understood processes like calving and melange dynamics using this area as a test bed? What about surface mass budget and snowfall and snow melt?

A lead in the sea ice – these fractures in the ice have sea water (the black) welling up between two thick plates of sea ice. The conditions were perfect for frost flowers to grow on the surface. Sea ice turns out to be a lot more interesting – and complex- than I’d ever imagined…

Now, as a glaciologist, I’ve mostly worked with the interface between atmosphere and ice sheet (at least the last 14 years or so, but I am also still (after my PhD topic on ice fracture and crevasses) interested in calving glaciers and the processes that control how fast icebergs form. And the fjord, Inglefield Bredning has *a lot* of calving glaciers in it. It is a natural laboratory for glaciology and for developing numerical models. Calving is actually a surprisingly difficult thing to model with computer models of glaciers.

Or perhaps it’s not that surprising?

Observations are difficult to get (to put it mildly). There are a number of (possibly wild) theories of “calving laws” that remain poorly constrained by observations as a result. Common parameterizations of ice flow makes it hard to deal with fast flowing glaciers where calving is common. Dealing with grounding lines, where glaciers meet the sea and start to come close to flotation can give notorious numerical errors and retreat requires the remaking of ocean grids in fully coupled climate models.

Satellite image from ESA’s Sentinel-2 satellite showing glaciers calving icebergs into the head of the Ingle field Bredning fjord. The black is open water, icebergs show up as blueish dots, the land is carpeted in snow. Low winter sun (in late September 2022) casts deep shadows.

These are not easy or computationally cheap problems to solve. And where there are at least thousands (maybe even tens of thousands?) of scientists working on atmospheric weather and climate modelling, the community working on ice sheet dynamic models is probably only in the low hundreds.

And of course, we really lack long time series of measurements – essential in a system that changes only s l o w l y, but likely irreversibly and which we are, only now as the system is changing rapidly, starting to understand.

This of course is why the fjord observation record of Steffen is so valuable – these are reliable, repeated measurements of ocean properties that are known to affect the outlet glaciers that meet them. It is indeed a natural laboratory.

What we are now also working on is a field lab to study these calving processes in-situ. I have already found the return to the field scientifically valuable. There is really no replacement for going to observe the earth system you want to understand. (My PhD supervisor used to call it “nurturing your inner glacier”). Observations taken in spring/summer 2022 have already changed how I think about some processes and hopefully the follow-up we have planned in 2023 will confirm our new theoretical framework.

Heading home from the deployment of instruments out near calving glaciers at the head of the fjord.

I am fortunate indeed in that at the same research department, we also have colleagues collecting and analyzing satellite data and developing the numerical models we want to use to understand how ice sheets fit into the earth system. All three of these elements – field, satellite and numerical model- are essential.

In this project we are using the satellite observations to extend the time series of field data and we can use both sets of observations together to develop and test a numerical model of this fjord and the glaciers that calve into it. The numerical model we can then extend to other glaciers in Greenland. Hopefully, we can also use this work to understand how Antarctic glaciers might also respond to a warming ocean. Ultimately, the aim of all this work is to understand the contribution of these glaciers to sea level rise both now and in the future.

This is not a frivolous question. In fact, if large (more than a couple of metres).of sea level rise is expected, it is a question that is basically existential for Denmark.

I will add more on the specifics and science in coming months, this is already long enough. However, I’d like to mention a couple of other points:

Firstly, DMI is by no means alone operating up here. Many of the key articles, particularly on glaciology in this region, have been written by the Japanese group at Hokkaido University and their collaborators at the Meteorological Research Institute, the national institute for polar research and others. We at DMI are also working directly with the Greenland institute of natural resources, Asiaq, GEUS, KU, DTU, AU, SDU, ESA, Eumetsat and many others in this research programme.

Secondly, if you want to read more about it, I made these comics for my kids featuring some of their Lego pieces while out in the field this year and last. They’re kind of fun (I hope) and also informative (I hope).

Finally, this work is currently being carried out under the auspices of the Danish National Centre for Climate Research (NCKF), funded by the Danish Government though with contributions also from other research projects mostly funded by the EU’s Horizon 2020 and Horizon Europe frameworks as well as ESA’s climate change initiative for the Greenland ice sheet.