Yesterday in 30 Day Map Challenge I rather hurriedly made a map showing the density of street trees in Copenhagen shown as hexagons. However, there is a big gap in the overall map, because the dataset I used only covered Copenhagen Kommune (local authority) area and Frederiksberg is a separate local authority area where I could not find the data. This was, to put it mildly a little irritating.
A fellow mastodon user (@tlohde) suggested using the outputs from openstreetmap to fill out the gaps. (And even helpfully provided some code to do so, which should tell you a lot about why I like mastodon so much). A very hurried 10 minutes reprocessing gives the revised map on the below, which has happily filled in much of the Frederiksberg gap. However, a closer comparison with the previous version above shows that, it’s not nearly the same…
The first thing to note is that the maximum number of trees in a polygon from the OSM data is 454, almost twice the 230 from the Copenhagen city council data set. The second thing is that I’m unsure exactly what time periods the Copenhagen data is from. It’s possible there has been a wholesale planting since the original data was collected, but there is no date on the opendata.dk page to indicate when it was sampled, so I can’t know how up to date it is. Openstreetmap may also be missing data of course (and a small remaining gap in northern Frederiksberg suggests it might be). However, the whole central axis of the plot has changed too.
I overlaid the individual trees on the map plot, the two are quite similar, and the long lines suggest tat plantings are following major roads in the city. I wonder however if the main difference is one of definition. Perhaps street trees from the Copenhagen kommune dataset does not include parks and of course those on private property, compared to those in OSM?
Does it really matter? Well maybe. Street trees provide a valuable service in communities: they shade the streets in hot summer days (and can lead to substantial cooling). They also soak up rainwater and their flowers and fruit feed city ecosystems, quite apart from their aesthetic properties. How to protect, conserve and expand the numbers if we don’t know where they are? Or are not for that matter?
I don’t really have time to dig down into this mystery further. 30 Day Map challenge is really about the tools but either way it’s a lesson. No matter how clever the tool, if the underlying data is missing, wrong or otherwise biased in someway, the map will also be wrong.
I’m tempted to add, that all maps are wrong, but some of them are useful..
The personal finance community have an important concept of “paying yourself first”*, by which they mean, that when your salary or other form of payment comes in, the first thing you should do is put a given percentage, 10% is commonly used, into a savings account. Only then should you consider spending the rest of your income.
I kind of like this as a concept, and I think it could very usefully be applied to other areas of my life, notably, which is where of course it comes into this blog, science. As I’ve got more senior I’ve found I’m spending more and more time on managerial tasks, meetings, emails, reports, proposals, supervision and less and less on actual science. This is probably fine, it’s the way of the world, but it’s also a pity when part of (most of?) the joy of science is really in the doing. That’s why we put up with paltry wages, high workloads, social media hostility and the rest.
Actually doing science is so much fun.
Admittedly, some of it is more type 2 fun (best enjoyed retrospectively, as anyone who has spent a month CMORising model output or digging snow pits in freezing driving snow conditions can tell you), than type 1 fun (enjoyed in the moment). Nonetheless, I occasionally feel I’m in danger of losing the thread of why I started in this career in the first place.
Type 2 fun: It took us 4 hours to locate and dig that lot out in wind and occasional blizzard conditions.
Autumn was absolutely and ridiculously hectic, many project meetings, as well as technical conferences and symposia, proposal deadlines, deliverable deadlines and one-off workshops. I welcome November with open arms. Finally time to do some actual work again! And in the way of paying myself forward, I have started two different but related tracks to get back into the groove this month.
The first, #30DayMapChallenge you can already see some entries for here on a dedicated page. The idea is a new map, according to the prompts from the website 30DayMapChallenge , every day. I’m certainly not going to make all 30. I will be doing well if I manage 10, but already after only 2 days, I can feel my geospatial mojo coming back. There’s nothing like practicing your GIS skills to make you want to do more of them
The second is #AcWriMo, academic writing month. I have 3 papers I’d really like to submit before the end of this year. I’m very close with one, fairly close with the second and to be entirely honest I’m not really sure where I am with the third… Now it may seem unwise to commit to 2 daily activities in November, while recovering from September and October, but in fact they’re pretty complementary. I plan to post maps that are relevant to, or even actually from the papers, and just the process of looking at data is a motivation to get the work done.
I will have the first 2 papers submitted by end November
I will write at least 20 minutes per day – every day!
I will write at least 8 hours per week
I will rediscover the joy of science.
Let’s call it paying myself first…
*Far be it from me to offer financial advice, but if I was a young graduate student, I’d be saving up pretty hard on whatever meagre wages I have. The research field can be fickle with contracts, even permanent jobs have to continue raising money and we can’t keep up the pace for ever. Nonetheless, I wouldn’t swap it for another job…
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.
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.
Trusted global GPS tracker buoy
Open met buoy
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.
Winter travel
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.
One of our buoys is found…
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.
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.
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.
At DMI we’re currently recruiting for student helpers to work in the National centre for climate research (NCKF) as a part time study job.
(Note that this is a special category of internship type job for students in receipt of a student grant in Denmark only and therefore has limited hours).
It’s a very exciting project, funded by the European Space Agency and in collaboration with the Horizon Europe project PolarRES.
The successful student will be using new satellite datasets to evaluate the performance of new state of the art climate models over the Greenland and Antarctic ice sheets. As you can probably imagine, we’re looking for a student with some experience of coding, in e.g. python and an interest in climate and ice sheet modelling.
The job posting is in Danish (machine translation works, try DeepL). It’s not actually required to speak Danish, however note bold text above!
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).
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.
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..
I was going to blog about this cool new paper that my colleagues at DMI have produced, but John Kennedy has as always done such a good job I will just point you over there…
Wondering whether a warm bias in the Arctic in ERA5 affects our estimates of global temperature change.
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:
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…
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:
Sterna Paradisaea 