sea level rise – Sterna Paradisaea

Freshwater Writing

It’s always nice to kick off a week with notification that a paper you have co-authored has been published.

In this case, and due to a magnificent effort by lead author Gavin Schmidt (who heaven knows must have many other things on his plate at NASA GISS right now), the” Datasets and protocols for including anomalous freshwater from melting ice sheets in climate simulations ” is now out in Geoscientific Model Development.

If that sounds a bit clunky, well it is. The idea is that the paper is a technical guidance, to help climate models (specifically for CMIP7), to include the effects of ice sheets into the earth system, without having to actually include a full ice sheet model, which turns out to be quite hard, particularly in Antarctica.

Even so there’s a lot of general interest in the paper, including how this is usually done now (there are a range of different approaches, each with their quirks). And then a particularly nice and clear section is given on all the many different ways that ice sheets lose ice. The figure below from the paper shows some of these and as they all have different downstream effects on ocean circulation, sea ice and of course sea level rise, it’s important to work out how to include them efficiently. The paper as it stands is a really nice introduction to the subject.

Figure 1 from Schmidt et al., 2025 showing a schematic of how ice sheets lose ice.

Icebergs are particularly interesting as a source, as the meltwater from these can take years to be added to the ocean, in which time, they will have drifted hundreds or thousands of kilometres. We have some suggestions on those too.

In any case, we hope this paper, which grew out of a technical online workshop on the subject, partly organised by our Ocean Ice project, will turn out to be a useful source for the groups that actually run the global climate models for CMIP and the IPCC. Many of these models are still in development or being initialised now, so time is already short for those of us involved in the technical parts of the exercise. The publishing process is slow, but this is also why preprints are so valuable. This paper in its submitted form has been up for months, it’s only now the final version is ready, but it hasn’t changed much. While it feels hard enough keeping up with published papers that preprints feel like a distraction, science is moving so fast, it’s probably essential. Maybe I’ll write more about that later. Of course preprints (and indeed published papers) can lead you astray, especially in fields you don’t know much about (as COVID was a helpful reminder), so perhaps sensibly the IPCC insists on acceptance of manuscripts before including them in their reports. Nonetheless, keeping up with preprints is now probably almost as important for scientists as keeping up with the published literature.

On the subject of the IPCC, I was reminded this weekend that it’s now less than 500 days until the submission deadline for the working group 1 part of the next IPCC report (AR7), so it’s time to start thinking about what are the priorities to get into the scientific literature to inform this effort. IPCC can only report published work, and doesn’t do its own, so now is the moment to pull out that unfinished but crucial piece of evidence of something or other relevant and get it submitted.

Not coincidentally, it’s time to talk about Academic Writing Month (AcWriMo). I actually try to write all through the year but November is time for a final push to try and meet my (usually far too ambitious) annual goals.

I had intended to start AcWriMo again this year, I’ve a huge backlog of papers to get done and it seemed a good way to start. However, a big proposal writing effort (more on here if the funding comes through) and a Hackathon (of which more also anon), both extremely rewarding and in fact also involving a lot of writing, somewhat derailed the first 10 days of my effort…

Now however it is time to focus on the remaining almost 3 weeks of November. The plan is one hour per day, except weekends, just focused on papers. I’ve put it in my calendar already. Let’s see if I can stretch more than that. Also non- negotiable is daily exercise. The fresh air and time away from the computer is almost as important as sitting down to do the work.

I’ve got an almost done experimental protocol to write for the PolarRES project (which finishes his month, so there’d be a nice symmetry to getting that done). And then there’s the much delayed reply to reviewers on our ice mélange study in NW Greenland as my main foci, but I also want to help my Hackathon group get their project knocked into shape, so some time will be spent there.

I’ve also got various diverse co-authored papers I need to contribute to, read,edit and give my options on. I hate to become a roadblock for colleagues so that also needs some attention but I’m for sure already out of time.

So if you want to see all stages of the sausage being made, follow along with the hashtag (#AcWriMo25) on socials, but hopefully you won’t see me there much because I #amwriting.

PROTECT: The Sea Level Rise Question

There is currently some discussion in the Danish media about sea level rise hazards and the risk of rapid changes that may or may not be on the horizon. Some of the discussion is about IPCC estimates. That’s a little unfortunate and in fact a bit unfair as the IPCC report has not been updated since 2021, nor was it intended to have been. In the mean time there has been a lot of additional science to clear up some of the ambiguities and questions left from the last report.

I’ve been working quite a bit on the cryosphere part of the sea level question of late, so thought I’d share some insights from the latest research into the debate at this point. And I have a pretty specific viewpoint here, because I’ve been working with the datasets, models, climate outputs etc that will likely go into the next IPCC report as part of a couple of EU funded projects. As part of that, we have prepared a policy briefing that will be presented to the European Parliament in June this year, but it’s already online now and will no doubt cross your socials later this week. I’m going to put in some highlights into this post too.

Now, I want to be really clear that everything I say in this post can be backed up with peer reviewed science, most of which has been published in the last 2 to 3 years. Let’s start with the summary:.:

The sea is rising. And the rate of rise is currently accelerating.
The sea will continue to rise long into the future. The rate of that sea level rise is largely in our society’s hands, given that it is strongly related to greenhouse gas emissions.
We have already committed to at least 2m of sea level rise by 2300.
By the end of 2100 most small glaciers and ice caps will be gone, mountain glaciers will contribute 20-24% of total sea-level rise under varying emission scenarios.
Antarctic and Greenland ice sheet mass loss will contribute significantly to sea-level rise for centuries, even under low emissions scenarios
Abrupt sea level rise on the order of metres in a few decades is not credible given new understanding of key ice fracture and iceberg calving processes.
By the end of this century we expect on the order of a half to one metre of sea level rise around Denmark, depending on emissions pathway. (If you want to get really specific: the low-likelihood high impact sea level rise scenario corresponds to about 0.9 m (on average), or at the 83rd percentile, about 1.6 m of sea level rise).
Your local sea level rise is not the same as the global average and some areas, primarily those at lower latitudes will experience higher total sea level rise and earlier than in regions at higher latitudes.
We have created a local sea level rise tool. You should still check your local coastal services provider, they will certainly have something tailor made for your local coastline (or they *should*!), but for something more updated than the IPCC, with latest SLR data, this is the one to check.

Sea level rise now is ~5mm per year averaged over the last 5 years, 10 years ago it was about 3 mm per year). Much of that sea level rise comes from melting ice, particularly the small glaciers and ice caps that are melting very fast indeed right now. Even under lower levels of emissions, those losses will increase. There won’t be many left by the end of this century.

Greenland is the largest single contributor and adds just less than a millimetre of sea level rise per year, with Antarctica contributing around a third of Greenland, primarily from the Amundsen Sea sector. The remaining sea level rise comes from thermal expansion of the oceans. Our work shows very clearly that the emissions pathway we follow as a human society will determine the ultimate sea level rise, but also how fast that will be achieved. The less we burn, the lower and slower the rise. But even under a low-end Paris scenario, we expect around 1 metre of sea level by 2300.

The long tail of sea level rise will come from Antarctica, where the ocean is accelerating melt of, in particular, West Antarctica. However, our recent work and that of other ice sheet groups shows that the risk of multi-metre sea level rise within a few decades is unrealistic. Again, to be very clear: We can’t rule out multiple metres of sea level rise, but it will happen on a timescale of centuries rather than years. High emissions pathways make multiple metres of sea level rise more likely. In fact, our results show that even under low emissions pathways, we may still be committed to losing some parts of especially West Antarctica, but it will still take a long-time for the Antarctic ice sheet to disintegrate. We have time to prepare our coastlines.

Greenland is losing ice much faster than Antarctica, and here atmospheric processes and firn and snow are more important than the ocean and these are also where the læarge uncertainties are. As I’ve written about before, that protective layer of compressed snow and ice will determine how quickly Greenland melts, as it is lost, the ice sheet will accelerate it’s contribution to sea level. This is a process that is included in our estimates.

There’s so much more I could write, but that’s supposed to be the high level summary. Feel free to shoot me questions in the comment feeds. I’ll do my best to answer them.

Five years ago, a small group of European scientists got together to do something really ambitious: work out how quickly and how far the sea will rise, both locally and on average worldwide, from the melting of glaciers and ice sheets. The PROTECT project was the first EU funded project in 10 years to really grapple with the state-of-the-art in ice sheet and glacier melt and the implications for sea level rise and to really seek to understand what is the problem, what are the uncertainties, what can we do about it.

We were and are a group of climate scientists, glaciologists, remote sensors, ice sheet modellers, atmospheric and ocean physicists, professors, statisticians, students, coastal adaptation specialists, social scientists and geodesists, stakeholders and policymakers. We’ve produced more than 155 scientific papers in the last 5 years (with more on the way) and now our findings are summarised in our new policy briefing for the European Parliament.

It’s been a formative, exhilarating and occasionally tough experience doing big science in the Horizon 2020 framework, but we’ve genuinely made some big steps forward, including new estimates of rates of ice sheet and glacier loss, a better understanding of some key processes, particularly calving and the influence of the ocean on the loss of ice shelves. More importantly for human societies, by integrating the social scientists into the project, we have had a very clear focus on how to consider sea level rise, not just as a scientific ice sheet process problem, but also how to integrate the findings into usable and workable information. In Denmark, we will start to use these inputs already in updating the Danish Climate Atlas. If you are elsewhere in the world, you may want to check out our sea level rise tool, that shows how the emissions pathway we follow, will affect your local sea level rise.

Our final recommendations?

Accelerate emission reductions to follow the lower emission scenario to limit
cryosphere loss and associated sea-level rise
Enhance monitoring of glaciers and ice sheets to refine models and predictions
Support the long-term development of ice sheet models, their integration into
climate models, and the coupling of glacier models with hydrological models, while
promoting education and training to build expertise in these areas
Invest in flexible and localized coastal management that incorporates
uncertainty and long-term projections
Foster international collaboration to share knowledge, resources, and strategies
for mitigating and adapting to global impacts

Small differences that make a really big difference.

I’m a co-author on a new paper that has just come out in GRL. It’s based on simulations we did with our collaborators in the PROTECT project on sea level contributions from the cryosphere. What Glaude et al shows is that, to quote the first of the 3 key points:

“With identical forcing, Greenland Ice Sheet surface mass balance from 3 regional climate models shows a two-fold difference by 2100”

In perhaps more familiar terms, if you run 3 regional climate models (that is a climate model run only over a small part of the world, in this case Greenland) with identical data feeding in from the same global climate model around the edges, you will get 3 quite different futures. Below you can see how the 3 different models think the ice sheet will look on average between 2080 and 2100. The model on the right, HIRHAM5 is our old and now retired RCM. It has a much smaller accumulation area left by the end of the century than the other two, which have much more intense melt going on in the margins.

Greenland Ice Sheet annual surface mass balance (a, b, c, 2080–2099 average) and annual surface mass balance anomaly (d, e, f, 2080–2099 average relative to 1980–1999) [mm WE/yr]. From left to right, RACMO (a and d), MAR (b and e), and HIRHAM (c and f). The equilibrium line (SMB = 0) is displayed as a solid black line in (d-f). Glaude et al., 2024, GRL.

In fact, by the end of the century, although the maps above seem to show HIRHAM having much more melt, there is in fact more runoff from the MAR model, because of this intense melt.

Spatially aggregated annual GrIS SMB anomalies (a), total precipitation (PP, b), and runoff (RU, c) [Gt/yr]. The solid lines represent the anomalies using a 5-year moving average, while the transparent lines display the unfiltered model output.

The surface mass balance (SMB) at the present day is in fact positive. This often surprises people, but SMB as the name suggests, only describes surface processes. Ice sheets can (and do) also lose a lot of ice by calving and subglacial and submarine melt. As SMB should balance everything if a glacier is to remain stable or even grow, present day SMB is usually 300 to 400 GT positive at the end of each year, and even so the Greenland ice sheet loses, net around 270Gt per year.

Our work here shows that, at least under this pathway, not only does SMB become net negative in itself by the middle of this century, there are significant differences in SMB projections between the estimates of how negative it will be, between the three RCMs. The global model we used, CESM2 under the high-end SSP5-8.5 scenario, is famously a warm scenario, but our estimated end of the century SMBs are extraordinary : (−964, −1735, and −1698 Gt per year, respectively, for 2080–2099). As I’ve discussed previously, one gigatonne is a cubic kilometre of water, 360Gt is roughly 1mm global mean sea level rise. (Though note your local sea level rise is *definitely* not the same as global average!) Even the lowest estimate here the is giving around 3 mm of global average sea level rise from surface melt and runoff *alone* by the end of this century each year. That’s pretty close to the modern day observed sea level rise from all sources.

And this is in spite of the fact that at the present day, the 3 models are rather similar in their estimates of SMB. The Devil is as usual in the details.

We attribute these startling divergences in the end of the century results to small differences in 1) the way melt water is generated, due to the albedo scheme (that is how the ice sheet surface reflects incoming energy); 2) but also due to the cloud parameters that control long-wave radiation at the surface, which again can promote or suppress melting. (We really need to know how much liquid water or ice there are in clouds, as this paper also emphasises in Antarctica); and 3) mainly down to the way liquid water that percolates down from the surface is handled in the snow pack. That is, how much air there is in the snowpack, how warm the snow is and how much refreezing can occur to buffer that melt.

The problem is that all of these processes happen at very small scales, from the mm (snow grains and air content), to the micron scale (cloud microphysics). That means that even in high (~5km) resolution regional models, we need to use parameterisations (approximations that generalise small scale processes over larger spatial and/or time scales). Small differences between these parameterisations add up over many decades. Essentially, much like the famous butterfly flapping its wings in Panama and causing a hurricane in Florida, the way mixed phase clouds produce a mix of water vapour and ice over an ice surface might ultimately determine how fast Miami will sink beneath the waves.

More data would certainly help to refine these parameterisations. The main scheme to work out how much liquid can percolate into snow was originally based on work by the US Army engineers in the 1970s. More field data with different types of snow would surely help refine these. Satellite data will be massively helpful, if we can smoothe out some wrinkles in how clouds (there they are again) affect surface reflectivity.

These 3 different types of processes also interact with each other in quite complex ways and ultimately affect how much runoff is generated as well as the size of the runoff zone in each model. So integration of many different types of observations is crucial.

“Different runoff projections stem from substantial discrepancies in projected ablation zone expansion, and reciprocally” as we put it in Glaude et al., 2024.

The timing and magnitude of the expansion of the runoff zone is quite different between the models, but all of them show a very consistent increase in melt and runoff over the next 80 years.

It’s probably also important to understand a couple of key points:

Firstly we ran a very high emissions pathway: SSP5-85 is probably not representative of the path we will follow in emissions (at least I hope not), but in this study we wanted to address the spread on different model estimates. And this is a way to get a good check on the sensitivity.

Secondly, the ice sheet mask and topography in these runs is kept fixed all the way through the century. This means we do not account for any elevation feedbacks (as the ice sheet gets lower because of melt, a larger area becomes vulnerable to melt because it’s lower and thus warmer), but we also don’t account for ice that has basically melted away no longer contributing to calculated runoff later in the century. Ice sheet dynamics are also not factored in.

Finally, we ran different resolution models, and that can have an impact particularly on precipitation and is one of the reasons why the new models we developed and have run in PolarRES (and which are now being analysed), have used a much more consistent set-up.

The 3 models we used, MAR, RACMO and HIRHAM have all been used in many different studies over both Greenland and Antarctica, but we haven’t really done a systematic comparison of future projections before. I think this work shows we need to get better at doing this to capture the uncertainty in the spread, especially when you consider that we’re now looking at using these models as training datasets for AI applications: training on each one of these models would give quite different results long-term. We need to think about how to both improve numerical models and capture that spread better. But ultimately, it’s how fast we can reduce greenhouse gas emissions and bend the carbon dioxide curve down that will determine how much of Greenland we will lose, and how quickly.

All data and model output from these simulations is available to download on our servers (we’re transitioning to a new one download.dmi.dk, not everything has been moved there yet). We also of course have data over land points and the surrounding seas, and we’ve run many more global climate models through the regional system to get high resolution (5km!) climate data also looking at different emissions pathways, if you’re interested in looking at, analysing or using any of this data – get in touch!

My warmest thanks to Quentin Glaude who led this analysis and special thanks to our colleagues in the Netherlands, France and Belgium for running these models and contributing to the paper analysis. Clearly, we have much work to do to get better at this ahead of CMIP7.

Group field trip the Greenland ice sheet: it’s important to see what you’re modelling actually looks like….

A Climate Atlas is discovered..

This post is in response to a thread posted on blue sky* by Jeremy Bassis and a discussion between Felicity mcCormack and Gavin Schmidt. All these people are well-respected climate scientists and the original thread was posted as a result of a Nature piece about operationalising climate models (and sea level rise), like we forecast the weather. This is something I’ve been thinking about for a while too, as sea level rise is an undeniable existential threat to my home country…

Anyway, I replied with a link to the Danish Climate Atlas – which to my mind is very much a model for how climate information should be done. I can’t give a full overview of the Climate Atlas, largely because it’s not my story to tell, but as Jeremy asked me to talk more in depth about it, and given the 300 character limit, I thought I’d formulate a few thoughts here first before sharing…

The climate atlas is not a book but a web frontpage that allows anyone with an internet connection to get high quality climate information at a local scale in Denmark. The map interface makes it easy and intuitive to use, and for detail a whole bunch of reports and datasets in different formats can be downloaded (everything from ASCII to GIS to netcdf). You can explore it here. All the data is given on a kommune (local authority) level except for sea level rise data which is divided up by coastal stretches.

Example of a Climate atlas figure – this is the overview figure, each local authority area is clickable for local information

For audiences that just want a quick message there are these easy to interpret icons with a key message below, like this one about higher water levels.

I was involved in the early stages and to my mind there are 4 crucial elements that have made it very successful:

Legal Requirement: Every local authority (a kommune, don’t think hippies, think regional councils) in Denmark has a legal obligation to make climate adaptation plans and to keep them updated. This element is important as it created awareness of the problem and effects of climate change and the necessity of investigating adaptation options. The initial plans were rather patchy and not very consistent with each other. Many regions had employed a consultant who was also maybe not an expert. Several kommune ended up with data based on CMIP resolution data! Hardly appropriate for a small local region in Denmark (which is barely resolved in most global climate models).
Data Foundation: At the same time we have been dynamically downscaling these simulations for decades, to provide really high quality locally bias corrected data (using also DMI’s long climatological time series to understand if and where biases exist). Colleagues at DMI identified a need to provide this in an easy to use format to everyone in the country. We had long ago discovered that working with motivated kommune employees led to a really good outcome: readable climate variables that are meaningful to an individual city, data formats that can be used by non-scienists (who definitely can’t deal with netCDFs).
Funding: Doing a data project properly requires money. The Climate Atlas is, compared to the cost of not doing anything, extremely cheap, nonetheless, it still costs something. Ear marked funding from the danish state to build up the Climate Atlas from the ground, to develop it as new needs are identified and to improve both communication and presentation has been crucial. Along the way several different needs have arisen (droughts, deep uncertainty in sea level rise), a new version will hopefully be coming soon.
Intense engagement: Probably the most crucial aspect to getting the climate atlas off the ground and into use has been communication over and over and over again. Not just initially with kommune to find out what they need (building on many years of background experience first), but also reaching out to special interest groups raning from local farmers in mid-west Jylland to sewage engineers, high school teachers and property developers. This continues, but has undeniably been helped by Denmark’s open trusting society and generous tradition of cultural meetings, continuing education and festivals.

The climate atlas in Denmark is the example I know best, we should be rightly proud of the team that constructed, maintain and continue to develop it. Other countries certainly have similar products in the Nordic and Blatic countries, and likely elsewhere, a network meets annually within the region to discuss developments etc. After a coincidental meeting, DMI was also invited to help develop one for Ghana, which is ongoing, and of course, will have completely different needs and requirements, However, the decision early one to base the back end of the Climate Atlas on open tools: python, cdo, github and CORDEX simulations, makes a lot of the learnings transferable.

If you want to know more, contact my colleagues at the Klima Atlas! I’m happy to put you in touch..

*As an aside, it’s interesting how many of the climate science and policy community have moved over to Blue Sky. It was rather quiet for a while but activity seems to have picked up. I’m not abandoning mastodon, which I actually prefer, but I’m happy to see an alternative to what has become known as Birdchan. I’d urge you to try it if you’re interested in a social media presence in a slightly more appealing environment. There are a number of handy tools, including fedica, that allow you to crosspost to multiple channels at the same time (including X, mastodon, bsky, TikTok and threads) and I’m also using the OpenVibe app, which has a common timeline from multiple platforms.

Breaking up is hard to do…

Way back in the mists of time, that is, early April, I and colleagues deployed some instruments on the sea ice in front of a number of glaciers in Northern Greenland, which I wrote a little bit about here.

Since then I’ve mostly been letting them get on with reporting their data back and occasionally checking on the satellite imagery to see how it’s looking in their surroundings.

It was about -30C and very cold when I left them out, so it’s sometimes quite hard to visualise just how much things will change over only a few months and to remember that at some point, they’ll need collecting

After a fairly melty start (yes, that is actually a technical term) to July, particularly in the northern part of the ice sheet (which you can see on the polarportal, see also below right) it’s time to start anticipating their collection.

We have a lot of advantages when it comes to coordinating this kind of project now, compared to the bad old days when imagery and communication were both scarce and expensive

For starters, there is Sentinel Hub’s EO browser, a course in which should be a requirement for every earth science adjacent subject in my opinion. EO Browser produces superb pre-processed imagery for free, such as this one, from the European Space Agency’s Sentinel-2 satellite yesterday

As you can see, the sea ice is still there but fracturing and patches of open water (in blue green) are now becoming visible.

Sentinel 2 satellite image processed on EO browser showing sea ice and ice bergs in front of Tracy and Farquhar glaciers.

If you’re out and about and only have your phone, there is also the excellent snapplanet.io app on your smartphone, with which you can create instagram ready snapshots of the planet or even animated gifs, with high resolution imagery a link away…

Now that’s what I call a fun social media* application…

Animated gif of satellite images showing the front of Heilprin glacier with icebergs and landfast sea ice.

Anyway, back to the break up. Every year, the sea ice forms in the fjord from October/November onwards, by December it’s often thick enough to travel on and then from April it starts to thin and melt and by late June large cracks are starting to form, allowing the surface meltwater to drain through. For a look at what happens if you get a large amount of melt from, say, a foehn wind, before the cracks start to open up, see this iconic photo taken by my colleague Steffen Olsen in 2019.

An extremely rare event, that nevertheless went viral

The other advantage we have working in this fjord is our collaboration with the local hunters and fishers. In winter they use dog sleds for hunting and accessing fishing sites, and to take us and our equipment out on to the ice. In summer, they are primarily using boats for fishing, hunting narwhal and, hopefully, collecting our equipment! Our brilliant DMI colleague Aksel who lives and works in the local settlement is also a huge help in assisting with communication and generally being able to get hold of things and people when asked.

We offer a reward for each buoy that is found and brought back to our base in Qaanaaq, so many of them in fact make their own way home. But we also work with our friends on a kind of remote treasure hunt, challenge Anneka style, with someone at home watching their positions come in via the satellite transmissions and sending updated information via sms to an iridium phone to the hunters on the boat…

I’m told it’s tremendous fun, with sharp eyes required, as even a bright orange plastic globe can be challenging to spot.

A floating trusted buoy in 2022.

I’ve never participated in this treasure hunt myself sadly, on land we generally see something like a spaghetti of arrows and spots via the Trusted global web api:

GPS positions from a trusted buoy.

We then have to try and superimpose these movements on the latest satellite images to work out if the buoy is floating or not, and then check to see if there is sufficient open water for a collection. Naturally working with local knowledge for this part is also absolutely vital.

The latest satellite images look like the ice has already broken up into large flakes close to Qaanaaq. I’ve annotated the Sentinel-1 image below as it is from a radar satellite that can see through clouds and the images can be a bit confusing if you’re not used to looking at them.

The scale of the massive melt on the ice sheet from the last few days is clearly visible in the dark grey rim on the glaciers. The open sea water is black and the sea ice shows up as geometric greys. This one is downloaded from the automatic archive my colleagues at DMI maintain around the whole coast of Greenland. It can be a handy quick check too.

Annotated satellite image of Kangerlussuaq/Inglefield Bredning (Gulf of Inglefield) fjord. The orange box shows where our study glaciers are located.

So, although the ice is starting to break up it’s at the tricky stage where it’s far from navigable by dog sled and certainly too difficult for boats, so it’s not quite the time to send out hunting parties for GNSS buoys.

It also means that when I go on holiday next week, I will not be quite leaving all this behind. I and my colleague in this project will be monitoring the movements of the buoys and the satellite pictures, as well as relying on our friends in the local community to let us know how the ice is looking and if they can get out to rescue our brave little sensors.

In the mean time I have plenty of data to start analysing and writing up. As ever massive thanks to the people of Qaanaaq and my cool colleagues for putting up with me and our GPS buoys. We hope to submit our first paper pretty soon..

Hopefully I’ll soon be able to look at a map like this one to see where they are (note that the precision on these buoy positions isn’t great, probabaly because they were thenbeing stored in a metal container).

*Yes, I’m probably a nerd. I’m a lot of fun** at parties too though.

**For a given value of “fun”.

Icebergs of Ilulissat

Icebergs in Ilulissat drift around the bay, sometimes fast, sometimes slow, sometimes they don’t move at all. They are drenched in the beautiful but sometimes stark light of the polar day. It’s scientifically interesting to watch them and speculate on their past trajectory and their likely future. It’s also extremely beautiful.

I’m once more on my way north to Qaanaaq, but this time I’ve been lucky enough to be able to enjoy some days off in Ilulissat. It’s an astonishing beautiful place, famous for the icebergs that come pouring out of the Ilulissat ice fjord just round the corner.

Normally, we’re only in town for one night as we have to switch planes to get to our field sites and this requires an overnight stay so it has been brilliant to be able to use a little holiday here.

Panorama over the bay in Ilulissat on a sunny evening

I have been using the time to work on some papers and try to clear some of the back log of reports and emails, but there has at least been some time for a couple of hikes in the back country nearby. I could post several hundred photos of icebergs and other magnificent views, but I was struck by the movement of icebergs in the bay outside my window while I was working yesterday.

Sometimes the big bergs seemed to move more, sometimes they seem stuck. I wanted to check this so I set up a time lapse on my tablet in the window of the guest house I’m staying in overnight (bearing in mind it’s the Polar Day so doesn’t actually get dark). I think it actually ran out of power before covering the full six hours I set it up for, so I’m now trying a full day. However, it was enough to show my perception was basically right and I have come to the conclusion the changing movement is related to the tides.

You can see the full almost a minute long film at my peertube account below.

This is also a bit of an excuse to play around with video editing a little, in this case I’m trying out canva, and to advertise my peertube account @icesheets_climate on TILvids.com.

As I’ve alluded to before, I’m trying out the non-corporate social media fediverse and it’s actually quite fun, though the videos are a bit time-consuming so I’m not quite sure how regularly I will manage to post these on my channel, but the clue is in the name on what most of them are about I guess…

Another iceberg near Ilulissat, this time one we visited by boat…

But I have gratuitously many photos on my pixelfed account and no doubt more to come. I’m also planning some icebreaker shorts describing different elements of the environment that I’m working on. We’ll have to see how much time I have to actually get those finished, they typically take a while!

Of course, these are not just pretty pictures – I have a professional interest in icebergs – my PhD was about ice fracture and applying models of crevasse formation to describe a new parameterisation of calving. One of the projects I’m working on in northern Greenland, (funded by the danish state through the National Centre for Climate Research, NCKF) is also focused on calving processes, and specifically the role of ice melange in the system. In fact, one of the papers I’ve been working on this week analyses those iceberg related datasets. It’s immensely valuable and rare that I have the opportunity to be able to focus on the process in the field at the same time as writing the paper.

I have 2 more days in Ilulissat, so no doubt there will be more walks around town and more iceberg photos, but I have sent the iceberg paper back to my co-authors now, so it’s time to focus on a new paper – and the climate of the polar regions in the future.

Heading North again…

I’m lifting my head from the semi-organised chaos that is my office, my home office, our family basement and the office workshop to write a quick post. This might be for reasons of despairing procrastination.

The reason for the chaos is that fieldwork season has come round again and on Friday I and my DMI colleague Steffen will be off to Northern Greenland once again. I’ll try to post a few photos to pixelfed (and perhaps even Instagram, though I swore off Meta products after the Brexit fiasco).

Buoys with GNSS and iridium transmitters (designed and assembled for us by Trustedglobal) ready to be taken out and deployed on the sea ice in northern Greenland. DMI’s geophysical facility building in the background.

This year my focus is again on the melange zone and we’ll be placing our instruments out to record the break-up of the fast ice. I also hope to get time to establish a new snow measurement programme – which I partly piloted last year. However, we will only be 2 scientists instead of the team of 4 this year, so this may have to wait until the second fieldwork period we have planned in early June (when the sea ice starts to break up). We are fortunate indeed that the local hunters, who still live a semi-subsistence lifestyle, are both incredibly competent and helpful and willing and eager to help when we go out on fieldwork.

This photo and excerpt was part of my contribution to a display at the Ocean decade conference in Barcelona next week. Last year we tested an open science variant of the trusted buoys above known as an Open Met Buoy. It’s incredibly smart, and completely open. You can download full instructions and make it and programme it yourself, or , as I did, order them from the german labmaker company who specialise in building open science kit.

Last year was a test of concept, and noone was more astonished than I was that the final set up not only survived the ice break up and floated safely down the fjord, we also managed to retrieve them and I hope they are waiting patiently in Qaanaaq so I can reprogramme and redeploy this year.

I wrote this piece on our work last year, promising a whole load of posts I didn’t end up having time to write. Sadly even my lego scientists never got an update. So instead of promising a whole lot of new posts, let me know what you’d like to see and read about either in the comments here or on my mastodon feed, and I’ll try to make some time to answer one or two of them while we go.

The area we travel to is going through very rapid changes now – not just climatic and environmental, but, perhaps even higher impact, social and cultural. I am privileged to be abel to witness it and we try hard to leave as little impact as possible.

At this stage it’s hard to imagine I’ll ever be ready to leave, but the clock is ticking down..

Local sea level rise: A question of gravity

I’ve explained several times in the course of media comments that, when it comes to the sea level rise that you experience, it really matters where the water comes from. This point still seems to cause confusion so I’ve written a super fast post on it.

Waves from the Storm Surge that hit Denmark in October 2023 credit: Sebastian Pelt

We very often talk about a metre or two of sea level rise by the end of the century, but in general that refers to global average sea level. And much like a global mean temperature rise doesn’t tell you very much about the kind of temperature changes you will experience in your location due to weather or climate, global mean sea level is also not very informative when talking about preparing your local community for sea level rise. There are other local factors that are important, (see below), but here I’m going to mostly focus on gravity.

Imagine that sea level is more or less stable around the earth (which it was, more or less, before the start of the twentieth century). Just like the moon causes tides because its gravity exerts a pull on the oceans, the ice sheets are large masses and their gravity also attracts ocean water, so the average sea level is higher closer to Greenland and to Antarctica. But there is only a finite volume of water in the oceans, so a higher sea level close to the ice sheets means lower sea levels further away in the tropics for example.

As the ice sheet melts and gets smaller, its gravitational pull becomes smaller so the average height of the sea around Greenland and Antarctica is lower than it was before, but the water gets redistributed around the earth until it is in equilibrium with the gravitational pull of the ice sheets again. The sea level in other places is therefore much higher than it would have been without that gravitational effect.

And in general, the further away from an ice mass you are, the more these gravitational processes affect your local sea level change. In Northern Europe, it often surprises people (also here in Denmark) to learn that while Greenland has a small influence on our local sea level, it’s not very much because we live relatively close to it, however the loss of ice from Antarctica is much more important in affecting our local sea level rise.

Currently, most of the ice contributing to sea level is from the small glaciers around the world, and here too there is an effect. The melt of Alaska and the Andes are more important to our sea level than the Alps or Norwegian glaciers because we are far from the American glaciers but close to the European ones.

This figure below illustrates the processes:

Processes important for local sea level include changes in land height as ice melts but also the redistribution of water as the gravitational attraction of the ice sheets is reduced. The schematic representation is from the Arctic assessment SWIPA report Figure 9.1 from SWIPA 2017

This is partly why the EU funded PROTECT project on cryosphere contributions to sea level rise, which I am currently working on, has an emphasis on the science to policymakers pipeline. We describe the whole project in this Frontiers paper, which includes a graphic explaining what affects your local sea level.

As you can see, it very much depends on what time and spatial scale you’re looking at, with the two ice sheets affecting sea level on the longest time scales.

**Figure 1** from Durand et al., 2021 Illustration of the processes that contribute to sea level change with respect to their temporal and spatial scales. These cover local and short term effects like storm surges, waves and tides to global and long-term changes due to the melting of ice sheets.

In the course of the project some of the partners have produced this excellent policy briefing, which should really be compulsory for anyone interested in coastal developments over the next decades to centuries. The most important points are worth highlighting here:

We expect that 2m of global mean sea level rise is more or less baked in, it will be very difficult to avoid this, even with dramatic reductions in greenhouse gas emissions. But the timescale, as in when that figure will be reached, could be anything from the next hundred years to the next thousand.

Figure from PROTECT policy briefing showing how the time when average global sea level reaches 2m is strongly dependend on emissions pathway – but also that different parts of the world will reach 2m of sea level rise at very different times, with the tropics and low latitudes in general getting there first.

What the map shows is that the timing at which any individual place on earth reaches 2 m is strongly dependent on where on earth it is. In general lower latitudes close to the equator will get to 2m before higher latitudes, and while there are ocean circulation and other processes that are important here – to a large extent your local sea level is controlled by how close to the ice sheets you are and how quickly those ice sheets will lose their ice.

There are other processes that are important – especially locally, including how much the land you are on is rising or sinking, as well as changes in ocean and atmosphere circulation. I may write about these a bit more later.

Feel free to comment or ask questions in the comments below or you can catch me on mastodon:

Building the Next Generation…

Hands-up who is looking for a new and very cool job in ice sheet and climate modelling and developing new machine learning tools?

REMINDER: 4 days left to apply for this PhD position with me at DMI looking at Antarctic Ice Sheet mass budget processes and developing new Machine Learning models and processes.

UPDATE 2: The PhD position on Antarctica is now live here. Deadline for Applications 18th February!

UPDATE: It’s not technically a PRECISE job, but if you’re a student in Copenhagen and are looking for a part-time study job (Note that this is a specific limited hours job-type for students in higher education in Dnmark) , DMI have got 2 positions open right now, at least one of which will be dedicated to very related work – namely working out how well climate and ice sheet models work when compared with satellite data. It’s part of a European Space Agency funded project that I and my ace colleague Shuting Yang, PI on the new TipESM project, are running. Apply. Apply. Apply…

I’ve written about the PRECISE project before, our new Novo Nordisk funded project looking at ice sheets and sea level rise.

This is a quick post to announce that our recruitment drive is now open. We’re split across three institutes. We are two in Copenhagen, ourselves at DMI and the Niels Bohr Institute at the University of Copenhagen, and then the University of Northumbria in Newcastle, UK.

The PI at the Niels Bohr Institute is the supremely talented Professor Christine Hvidberg, aided by material scientist and head of the institute, Joachim Mathiesen. I am leading for DMI, and the Northumbria work is led by Professor Hilmar Gudmundsson. We are also very fortunate to have the talents of Aslak Grindsted, Helle Schmidt, Nicolas Rathmann and Nicolaj Hansen already on board.

The project is already very cohesive between institutes, we’ve been working together for some time already and know each other well.

We have a good budget for travel and exchanges between groups, workshops, symposia, summer schools and the like, but perhaps more importantly, all the positions are focused at the very cutting edge (apologies for the cliche) of climate and ice sheet modelling. We are developing not just existing models and new ways to parameterise physical processes, but we also want to focus on machine learning to incorporate new processes, speed-up the production of projections for sea level rise, not forgetting an active interface with the primary stakeholders who will need to use the outcomes of the project to prepare society for the coming changes.

There’s also a healthy fieldwork component (particularly in Greenland, I don’t rule out Antarctica either), and if you’re that way inclined, some ice core isotope work too. So, if you’re looking for a new direction, feel free to give me a shout. I’m happy to talk further.

Links to all the openings, will be updated as they come out, these are currently open and have deadlines at the end of January:

Newcastle: A three-year postdoctoral research position in machine learning emulators of ice-ocean processes

Newcastle: A two-year postdoctoral researcher (PDRA) position in subglacial modeling of the Antarctic Ice Sheet

Copenhagen (NBI) PhD Project in Greenland ice sheet climate and precipitation variability

Copenhagen (DMI) PhD Project in Antarctic ice sheet surface mass budget (also keep an eye here, where there are also some other interesting jobs announced)

photo showing a small white tent on a snow covered sea ice surface with people dressed in thick warm clothes dropping instruments through a whole in the ice. The sky is a clear blue fading to vioet and pink at sunset — Field camp on sea ice, northern Greenland 2023, measure ocean influences on calving outlet glacier.
(Photo credit: Ruth Mottram, DMI)

A cryosphere call to action..

The International Cryosphere Climate Initiative has put together a new petition for scientists to sign. I’m a little sceptical that this kind of “clicktivism” makes much difference, but there are many many lobbyists from polluting industries at the COP28 and rather fewer scientists. And how else to draw attention to what is one of the most visible and urgent effects of climate change?

The petition is aimed at:

” all cryosphere scientists globally; as well as those working on emissions pathways: and those in the social sciences with research on adaptation, loss and damage and health impacts. This includes research and field associates, as well as doctoral students — because you are the future, and will be dealing with the impacts of climate change in the global cryosphere throughout your lives, as well as your professional careers.”
ICCI

The list of signatories so far already includes many rather senior scientists, so take this as a challenge to add your signature if you work in the cryosphere/climate space. It takes only a minute to sign and there are many familiar names on the list.

I’m not sure how else to emphasise the urgency of real action at COP 28.

Small bergy bits in the bay near Ilulissat, with Lego Ice Man for scale (and an important message)

As a coincidence though, and as I posted on mastodon the image below appears in Momentum, a plug-in on my web browser with a new photo every day. Today’s is this beautiful image of the Marmolada glacier in Italy by Vicentiu Solomon.

It’s a gorgeous but very sad picture – this is one of the faster disappearing #glaciers in the world and to hear more about the consequences of cryosphere loss, take a look at the policy brief produced by the PROTECT project on the sea level rise contributions from glaciers and ice sheets. It also contains this eye opening graphic:

A 2 metre rise in sea level is almost inevitable. The uncertainty is on the timing which is somewhere between one century and the next 2 thousand years, depending on where you are in the world, but, more importantly given COP28, how fast fossil fuels are phased out. You can download the whole thing here.

So there you have it. Here’s a reminder of the petition from the International Cryosphere Climate Initiative.

Share this:

Share this:

Share this:

Share this:

Share this:

Share this:

Share this:

Share this:

Share this:

Share this: