The summer period is traditionally a time to get a lot of work done. Perhaps it’s a bit paradoxical that just when the weather is at it’s nicest I shut myself away inside and start coding, compiling, pre and post-processing and analysing data. It’s also of course the time when the office and my meeting calendar is (usually) at it’s quietest. July is the holiday month in Denmark, most of my colleagues seem to take 3 weeks off and I have become accustomed to the same. It’s incredibly important and reviving to take the time off. I always come back re-energised and revitalised, and this year I feel like I need it extra much. In late July, the BBC starts to broadcast the Proms concerts from the Albert Hall and it’s perfect music to listen to while coding.

This summer I have a lot of simulations planned for the PROTECT project on sea level rise, particularly climate simulations in Greenland but also surface mass balance in Antarctica. I have 3 projects funded by ESA (the European Space Agency) under their climate change initiative, which both need some attention. I will (be trying to) assimilate satellite observations of ice surface temperature on the ice sheet and sea ice concentration in the Arctic into our climate models to improve Arctic climate simulations. It’s going to be fairly challenging to get the system working.

Then I need to also spend some time working on the Greenland ice sheet data too, after our papers from the last 2 years that gave a kind of health check to the ice sheet. We also showed how much melt could be observed compared with what climate models were expecting, and clearly something somewhere is going quite fast…

After several years of general overwhelm (and if I’m honest a small side-helping of procrastination), I finally have a long-awaited paper coming out on Antarctic Surface Mass Balance and a model intercomparison, hopefully in the next few weeks. Then there is a proposal as part of a Horizon Europe consortium in progress and preparations for our newly funded Horizon 2020 project PolarRES – due to start on the 1st September. Finally, the data we collected in Qaanaaq as part of the National Center for Klimaforskning (more on these projects in a later blog – hopefully!) needs to be processed, analysed and put to good work.

There are several other papers coming out shortly on which I am a co-author too, so, busy times.

I very often take a break from social media at this time of year too (not always!) and so it is this year. I have an extra long summer holiday this year as I have some old leave to use up and although I find myself working the first week, I intend to use the rest of the time to reconnect with the family. I have also been finding it increasingly hard with a fractured work day and many many different commitments to do the focused work that I enjoy so much. I’m slightly reviving this blog for a bit more detailed engagement and stepping back a bit from Twitter for the summer. I don’t promise to not check in at all. but you won’t see me around much!

One thing I will be finalising is the Bat Girl and Ice Man comics I made for my children while I was in Greenland this year – some reformatting and the remaining translation into Danish is still required so I will be using the train trip to the mountains this year to do that. Many thanks to Andrea especially for proof-reading and ideas and also to Steffen and Marianne as well as our friends in Qaanaaq, Gustav, Peter and Qillaq for being models in the story!

Of course, the machine keeps on rolling forward. The Polar Portal is still online and working well with full near real-time information on Arctic cryosphere and the Greenland ice sheet surface mass balance. The melt season is in full swing, and melt area is pretty wide, but the losses have been balanced to some extent so far by late spring snow and rain on the ice sheet – a reminder that we always need to remember a large amount of the melt refreezes in the snow pack.

Anyway, this is basically a long post to say, see you in mid-August and take it steady…

This post was first published on the ice2ice blog though I have extended and expanded it with some extra details.

 Ice2Ice is a large project funded by the European Research Council in a Synergy grant. It is one of my current main sources of funding and is a pretty exciting piece of work, looking at abrupt climate changes in the past (when the temperature around Greenland suddenly increased by around 10-15C in about a decade) known as Dansgaard-Oeschger cycles.  Go and check out the webpage and also this very nice overview on science nordic including cool film showing ice core processing . 

Glaciers in Greenland lose mass by melt and runoff, by calving and by submarine melt that happens at the front of outlet glaciers that terminate in the ocean. Submarine melt occurs because the ocean water is (relatively) warmer than the ice, but it goes much faster where there is turbulent water mixing the layers by the glacier. Probably the most important source of turbulence are plumes of water that emerge at the base of the glacier where it terminates in the fjord. Penny How, a scientist at the University of St Andrews recently wrote a very nice blog post giving an overview. Including this nice GIF showing a very clear plume coming out the front of Tunabreen, a glacier in Svalbard:

The water is generated by melting mostly at the surface though also at the bed of the glacier. Meltwater flows like rivers through systems of englacial channels to finally arrive at the bed where it makes its way, eventually, to the end of the glacier.

Unfortunately these channels are pretty hard to map, and there are lakes and areas at the bed where water can be stored. The plumes themselves are rather hazardous to observe as they are often inaccessible and in front of actively calving sections of the glacier. There have been a few studies, but often these are snapshots in time and it is difficult to assess how important these processes are to the overall mass budget of the ice sheet.

Therefore we have to turn to models to work out how important plume processes are for submarine melt. In our recent paper with Slater et al (2017), we contributed data from the HIRHAM5 RCM to look at runoff within a catchment in Greenland. The case study was based at Kangiata Nunata Sermia glacier, in the Godthåbsfjord area of south western Greenland. It’s a relatively accessible glacier showing many of the common processes for Greenland outlet glaciers and has a fair bit of data available. The Langen et al (2015) paper showed that HIRHAM5 performs pretty well in terms of modelled runoff in this region as I detailed in this post.

The modelled runoff was used in two different models of subglacial plumes, including one implemented in MITgcm, in order to determine what configuration of subglacial hydrology and plume distribution along the ice front was most likely.  The models were compared with a time lapse photos of the ice front showing plume activity at the surface.

For a large proportion of the summer, the modelled catchment runoff greatly exceeds the discharge required to create a plume that would reach the fjord surface, yet there are extended periods when there is no plume visible from the time lapse pictures. This can only be explained by the runoff emerging into the fjord in a spatially distributed fashion. In the paper we therefore argue that subglacial drainage near the glacier terminus is often spatially distributed, formed either from numerous point sources of subglacial discharge, or a single but very wide subglacial channel or possibly a complex combination of the two.

There are two implications from this work. Firstly, a more spatially distributed submarine plume gives a higher total melt than a single concentrated plume but this melt rate is still unable to explain the mass loss at the terminus when considering the ice velocity at the terminus, suggesting that calving is still the most important mass flux term at this glacier. Secondly, the modelling study found that the distributed hydrology, suggested by the results leads to a more direct ice flow response to high surface melt rates and this response most likely scales with catchment size.

Probably the most important result to come out of this study is that longer time series of observations of plumes, in combination with the modelled runoff lead to a dramatically different understanding of key processes within the fjords when compared to those suggested by simple snapshot observations in earlier studies.

So, does this matter – well, probably. These kind of studies sprang up in the wake of a paper published by Eric Rignot and friends. They were almost the first to really look seriously and consistently at the amount of ocean-driven melting going on at these fronts in Greenland and they found summer melt rates at a number of glaciers that would indicate almost as much mass loss as from calving rates. Out of this early work, the NASA funded OMG (Oceans Melting Greenland) project emerged, which is currently contributing a huge amount of data that will be very useful – including the bathymetry of many fjords in Greenland which are still in general rather poorly mapped.

This focus is welcome, the ice sheet-ocean interaction is incredibly poorly observed and we are very much reliant on imperfect models. However,  our study shows that meltwater driven plumes and melt rates at the front of this glacier is rather a small source of glacier retreat when compared to calving rates or surface melt and runoff. Calving is important because a large amount of ice can be lost very quickly as these bergs show. These calved off the front of the same glacier as in this study but in 2009 when I happened to be in Greenland. the glacier, Kangiata Nunata Sermia was previously called the Godthåbs glacier, after the earlier Danish name for the town of Nuuk. It is also often known by the abbreviation KNS in the scientific community.

If this process is similar elsewhere in Greenland it suggests that submarine melt may be less important to rates of ice mass loss and consequent sea level rise. This is not to say it is not important elsewhere in Greenland, and indeed under climate change scenarios with enhanced melt and much warmer ocean waters making it way into the fjords, this may well change and could potentially become much more important.

UPDATE: The presentation from the meeting is now here (pdf): SFWI_pres_for_sharing.

I have tried to list all the different people and websites that provided material for this presentation, but if I have forgotten anyone, please do let me know and I will be more than happy to add an acknowledgement. 

Normally I work on the continental or hemispheric scale, concentrating on Greenland and the Arctic. Next week, I have a new challenge, to go much more local than that, to the country and even county scale.

I have been asked by the Staffordshire Federation of Women’s Institutes to give a talk on Climate Change next week. A rather broad subject!

The WI is a very long-standing and well-established institution in the UK and my mother, (who is of course the one who roped me in to it) has been a member since I was tiny wee thing. Outside the UK the WI are probably mostly known from the very successful film Calendar Girls.

These inspiring women have showed themselves to be a formidable lobbying force over the years and subjects as diverse as bees and pesticides to care for people with dementia and the plastic bag tax. Years ago, I recall my mother coming home from a WI meeting and talking about the ozone hole, one of the earliest organisations to start talking about it, so it is not a particular surprise they now have a focus on climate change. They now have a climate change ambassadors programme.

Each area has to organise themselves and decide what they would like to do as part of this, so as partly a kick off to that process and as part of their science committee activities (It’s not all Jam and Jerusalem at the WI these days apparently) I will be presenting in Stafford at the county council chambers on the 6th July 1.30-3.30pm.

As part of the programme, Staffordshire County Council will also be sending a representative to talk about how the County is responding both in terms of managing impacts and reducing emissions towards achieving the UK’s targets.

It’s going to be interesting talking about climate change both observed and projected in the UK, happily, the UK Met Office is a world leader in this and the very friendly Mark McCarthy has provided me with a bunch of data to distil down and prepare some visualisations from (see graph below for a quick and dirty look at some data)

I also plan to talk about the basic science of climate change, how it has developed, how it is observed and how we make projections and what we expect for the UK and Europe over the next decades to centuries. I have called it questions and answers since I hope that people will ask questions as we go through. From talking to people everyday, it’s clear there are a lot of questions people have about climate change and the impacts and the sciense. I also hope to talk about some of the options we have for tackling emissions and how to deal with the impacts. Copenhagen is a great case study for both of these elements. This is quite a lot for a short hour or so talk, but let’s see how we get on!

It’s open to the public so if you happen to be at a loose end on a Wednesday afternoon and fancy it, I believe you can get tickets via the following secretary@sfwi.org or telephone 01785 223838.

In the mean time, should any members of the WI or indeed other Staffordshire residents who happen to be reading this, have any questions or ideas that they would like addressed specifically, please do feel free to leave a comment or ask me on twitter.