new ice2ice paper-Action at the glacier-ocean interface

by Ruth Mottram and Peter Langen

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.  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 (2014) paper showed that HIRHAM5 performs pretty well in terms of modelled runoff in this region.

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.

Fig. 1. Illustrations of plume state classification. (a) Plume state=−1, ice tongue present. (b) Plume state= 0, no ice tongue and no surface expression of a plume. (c) Plume state= 1, plume visible adjacent to glacier terminus but is contained within a few hundred metres of the terminus. (d) Plume state= 2, plume visible and flows down-fjord at surface for a number of kilometres.
Fig. 1. Illustrations of plume state classification. (a) Plume state=−1, ice tongue present. (b) Plume state= 0, no ice tongue and no surface expression of a plume. (c) Plume state= 1, plume visible adjacent to glacier terminus but is contained within a few hundred metres of the terminus. (d) Plume state= 2, plume visible and flows down-fjord at surface for a number of kilometres.

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.

Fig. 2. (a) Air temperature from KNS1 and NUKL PROMICE stations. (b) Modelled runoff. HIRHAM5 (orange) delays runoff using a parameterisation based on surface slope. PDD model (green) assumes instantaneous runoff. PDD delay (pink) uses a transit velocity of 0.05 m s−1 from point of production to the terminus. PDD rapid (purple) uses a transit velocity of 1 m s−1. The green curve has been smoothed using a 3 d moving window, the pink and purple curves using a 6 h moving window. Large discrepancies between HIRHAM5 and the PDD model arise due to rainfall events (e.g. days 177 and 181). (c) KNS1 daily ice velocity. (d) Plume state as described in Figure1.
Fig. 2. (a) Air temperature from KNS1 and NUKL PROMICE stations. (b) Modelled runoff. HIRHAM5 (orange) delays runoff using a parameterisation based on surface slope. PDD model (green) assumes instantaneous runoff. PDD delay (pink) uses a transit velocity of 0.05 m s−1 from point of production to the terminus. PDD rapid (purple) uses a transit velocity of 1 m s−1. The green curve has been smoothed using a 3 d moving window, the pink and purple curves using a 6 h moving window. Large discrepancies between HIRHAM5 and the PDD model arise due to rainfall events (e.g. days 177 and 181). (c) KNS1 daily ice velocity. (d) Plume state as described in Figure1.

ice2ice in the media-UN international day of women and girls in science

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Article in ScienceNordic

The 11th of February was the UN international day of women and girls in science.

Both ice2ice postdoc Helle Astrid Kjær and DMI researcher Ruth Mottram has been very active tweeting about ice2ice activities (@H_A_Kjaer and @ruth_mottram) and have also used the #actuallivingscientist, which is used to describe what scientist actually work with. This was picked up by ScienceNordic, which is a news media for Nordic science. They used the two tweets from Helle and Ruth in their article on 11th of February celebrating UN international day of women and girls in science.

The full story can be found in english here.

And in danish here.

Other active ice2ice tweeters are:

 

 

Ice2Ice in the Norwegian news again

klassekampen-8-2-17The Norwegian newspaper Klassekampen has a very nice 2 page article on the ice2ice project. The interview with Principal Investigator Eystein Jansen focusing on abrupt changes in the Arctic climate.

Project partners can find the full text in the ice2ice dropboc

ice2ice in the media -Nordic project will solve a riddle of dramatic climate change

9th of February 2017 ScienceNordic.com featured a long article about the ice2ice project and how we seek to reveal the causes of rapid climate change. The article was written by Catherine Jex , heavily quotes DMI ice2ice researcher Ruth Mottram and also has a video interview with ice2ice Paul Vallelonga as well as with master student Lisa Hauge.

The full article can be found here , a danish version was published at videnskab.dk can be found here. The news story also featured in the large danish newspaper Jyllandsposten.

ice2ice was featured in ScienceNordic
ice2ice was featured in ScienceNordic

 

Holocene workshop in Dronningmolle

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Paul Valleonga and Ray Bradley discussing Greenland temperature trends from lake sediments and ice cores.

The 3-day Ice2Ice Holocene workshop took place from the 23rd to the 25th of January in Dronningmølle, DK. 26 participants mainly from the Ice2Ice network were involved in a dynamic exchange of knowledge and ideas on the climate of the Holocene epoch as seen from different records. The format of the workshop was open and informal something that allowed for more discussions than talks and allowed the participants to present data and ideas.

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Audrey Morley giving a potential explanation of the Holocene climate changes by changes in the position of the atmospheric jet, which could be driven by changes in the latitudinal temperature gradient.
The 2 invited talks from Audrey  Morley (National University of Ireland, Galway) and Camilla Andersen (Geological Survey of Denmark and Greenland) initiated a fruitful exchange of ideas while talks by Martin Miles, Kerstin Perner, Vasileios Gkinis and Trond Dokken gave an overview of the data based picture of the Holocene climate as it is seen in ice and marine cores. Some of the discussions particularly focused on seemingly common climate signals around the mid Holocene and resulted in the initiation of future collaborations and projects integrating climate records focusing in that particular period. There also seems to be anticipation in the promising Bromine records that Niccolo and Paul are working on, the upcoming NEEM water isotope diffusion reconstruction by Vasileios and the planned transient Holocene run by Kerim with focus on the Scandinavian pattern. Future strategies on tephra studies have also been the subject of a discussion on Tuesday evening.
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The tephra team in discussion of future strategies

The art of collaboration – a summary from the Ice2Ice PhD bootcamp

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Photo: Mads Poulsen

The second edition of the Ice2Ice PhD bootcamp recently came to an end, this time held in Geilo in the midst of the Norwegian winter, a couple of hundred kilometers to the east of Bergen. Based on the idea that each PhD student should benefit, in term of hers/his own project, from collaborating with other students working on related problems, the fourteen participating PhD students were divided into three groups several months prior to bootcamp. Within each group, a project was defined and sufficient preparations were made on beforehand such that the bootcamp week provided the ideal surroundings and time to work intensively on the project, and to answer the related scientific questions.

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Photo: Martin Olesen

One group worked on the momentum balance of the Northeast Greenland Ice Stream (NEGIS) outlet glaciers and had a specific emphasize on the potential back-resistance provided by the glacier tongue. Another group investigated the possibility to establish a self-sustained extensive sea ice cover in the North Atlantic in a coupled general circulation model by assimilating sea ice in an energetically consistent way. The last group focused on comparisons of proxy records obtained from sediment- and ice cores, specifically sea ice reconstructions based on Bromine enrichment as seen from the Greenland ice sheet and concentrations in sediments of organic matter from diatoms that live below the sea ice edge. Each group were guided by a mentor of their own choice, who were either available through a web connection throughout the week or were present at the bootcamp itself.

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Photo: Mads Poulsen

Besides the group work, the bootcamp also hosted scientific talks by mentors Rasmus Anker Pedersen (PostDoc, Centre for Ice and Climate) and Lars Henrik Smedsrud (Professor, University of Bergen) as well as student-organized seminars on plotting possibilities with python and GMT, and proxy interpretations and uncertainties. The week culminated with a presentation by each group on the results obtained during the bootcamp and on the possible prospects.

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Photo: Martin Olesen

Despite the military discipline which is associated with a bootcamp, the week did allow for a few cultural and social inputs. The owner of the bootcamp venue gave a brief introduction to the Hardanger fiddle, a delicate Norwegian instrument, and during Thursday a couple of hours of break were taken away from science as the groups went for a 5km dog sledge ride in the outskirt of Geilo.

 The results from the three groups, as well as the perspectives and the possibilities to integrate the projects further into the Ice2Ice synergy, will be presented on the all-staff meeting in Myrkdalen in March.

ERC featuring Ice2ice in their recent newsletter

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ERC writes in its newsletter “With an ERC Synergy Grant, Prof. Jansen and three Nordic world class researchers are currently investigating the dramatic loss of Arctic sea ice.”

In their last newsletter of 2016 the European Research Council (ERC) puts the spotlight on the ice2ice project and writes: “With an ERC Synergy Grant, Prof. Jansen and three Nordic world class researchers are currently investigating the dramatic loss of Arctic sea ice.” The article includes a picture of the flagpole on top of the Renland ice cap in East Greenland that mark the multinational effort.

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Science diplomacy

In October the ERC arranged a conference focusing on how frontier research can contribute to science diplomacy. The conference included a presentation of the ice2ice project presented by the Ice2Ice Coresponding Principal Investigator Eystein Jansen.

In the editorial to the newsletter, Federica Mogherini, the High Representative of the European Union for Foreign Affairs and Security Policy and Vice President of the European Commission, writes “Scientific cooperation in the Arctic can help stabilise an area where there is much potential for collaboration as there is for competition.”

ERC to reinstate Synergy Grants call

ERC has also announced that they will open another call for Synergy Grants and there is an article covering this in the newsletter. In 2014, the Scientific Council established an ad hoc group tasked with assessing the outcomes of the two synergy calls. In March last year ice2ice was the first project that the evaluation committee would meet with and we believe that this meeting has strongly contributed to the fact that the group recommended reinstating the synergy grant scheme.

Based on the groups findings the ERC President stated: “The Synergy Grants awarded so far have shown that this funding fosters interdisciplinary research and can trigger unconventional collaborations, allowing for the emergence of new fields of study. They will contribute significantly to fill a gap in EU funding for frontier research.” The decision to open another Synergy Grants call is welcomed by the Ice2ice team.

A warm arctic

The Warm Arctic workshop was held at DMI on the 5th and 6th December with several invited guest speakers from outside the ice2ice group. Svend Funder and Kurt Kjær from the Centre for Geogenetics at the Natural History Museum of Denmark in Copenhagen gave a good introductory overview of the current state of the art in terms of paleoproxies for Arctic sea ice extent and ice sheet extent in Greenland respectively. This was excellent framing for the remainder of the workshop.

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Sea ice processes are not straight forward. credit Vihma

Timo Vihma from the Finnish Meteorological Institute contributed an interesting talk on connections between the Arctic and the mid-latitudes including a very comprehensive diagram showing important processes and linkages, while on the second day, external speakers Wieslaw Maslowski and Dirk Notz (remotely) gave a nice overview of the state of the sea ice modelling from their respective groups, leading to an intense discussion on whether the ocean or the atmosphere was the dominant driver of change in the Arctic. Dirk Notz work shows nicely that sea ice decline follows emissions pretty directly. Internal speakers from DMI, included Rasmus Tonboe who gave a good overview of current sea ice data available from EUMETSAT and Torben Schmidt handled the modelling side with a look at multidecadal variability in the Arctic ocean.

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Notz talked about the effect of global CO2 on sea ice

Various ice2ice members also gave talks on different aspects of the project including a presentation by Shuting Yang on the Arctic sea ice loss and Northern hemisphere winters. There was a very comprehensive discussion by Peter Langen on Greenland ice sheet surface mass balance, some early work from Martin Stendel on the Arctic seesaw when there is little or no sea ice and PI Jens Hesselbjerg Christensen on the state of sea ice in a 1.5C world (spoiler: there won’t be very much). Rasmus Anker Pedersen also showed some of his work on the atmospheric response to a sea ice free Arctic.

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credit Svend Funder

As the aim of the workshop was to produce a review paper on the subject, there were two wide ranging discussion sessions where a very wide range of related topics were explored, including the aforementioned question of the relative importance of ocean and atmosphere and how the processes and feedbacks between the two might look. There was also much discussion on ways to improve sea ice representations in models and the importance of both including more comprehensive processes and improved model resolution in both ocean and atmosphere models. Finally, the workshop participants structured these issue into a format to create both a publication and potentially a conference session in the future, watch this space!

The workshop was organized by Christian Rodehacke, Peter Langen, Shuting Yang and Jens Hesselbjerg and was held at DMI.

Video: Ice cores – Revealing secrets of a past climate

Ice cores from the ice streams of north-eastern Greenland can tell us much about the climate of the past as well future sea level rise. Learn more in the video above.

For the first time an international group of scientists will drill a deep ice core into a fast flowing ice stream on Greenland. The international project EastGRIP, is lead by Ice2Ice parter Centre of Ice and Climate at the University of Copenhagen.

During the summer of 2016 a team of researchers and students built the base on the ice stream in northeast Greenland, started a comprehensive scientific surface field campaign, and initiated the ice core drilling.

The aim of the project is to better understand the dynamics and properties of the fast flowing ice stream. By the time they reach bedrock in the year 2020, the team will have extracted nearly 2700m of Greenland ice giving a 100,000 year old climate archive.

ICAT PhD school – a great success!

The ICAT PhD school was held from Monday 31/10 to Saturday 5/11/16. The Ice Core Analysis and Techniques (ICAT) PhD school supported by ice2ice and hosted over 30 students from 13 countries at CIC in Copenhagen. Through a mixture of hands on exercises in the three ice core laboratories, a mixture of lectures all related to ice cores, and several social events to enhance colaborations between students, the students learned all there is to know about ice cores. With student responses like “It was an awesome experience”, “congratulations on a great course-I am very thankful” and “This was a phenomenal PhD course” we hope to secure enough funding to be able to run it again next year.

The ICAT PhD's in the limestone quarry at Faxe
The ICAT PhD’s in the limestone quarry at Faxe

The ICAT PhD school was run for the first time this last week (31/10-5/11). The course was intended to increase the knowledge on ice core analysis techniques (ICAT) and people from more than 13 countries participated. The students had a diverse background; most were already familiar with ice cores, working on a particular proxy from ice cores, but also a few ice sheet modellers, climate modellers and people working with other paleo-archives attended, among these were 4 ice2ice participants.

Lots of discussion between the students in the breaks.
Lots of discussion and collaboration between the students in the breaks.

All days started with 5 minute presentations by students. It was great to see the diversity of the students and this way the newest research within ice core science was well represented. A number of Centre for Ice and Climate’s own scientists continued with lectures covering ice core history, water isotopes, Continuous flow analysis techniques, gas extraction and analysis, ice core drilling, dating of ice cores, borehole measurements, multi core variability, statistics and trends, water isotope modelling, ice sheet flow and comparison to other paleo-archives. Furthermore, the invited speakers Professor Joe McConnell, from the Desert Research Institute, Nevada talked about his research in Anthropocene contaminants as observed in ice cores measured by continuous flow analysis and professor Edward Brook, College of Earth, Ocean, and Atmospheric Sciences, Oregon State University gave lectures about the extraction of greenhouse gases and the changes of them as observed in ice cores.

Sune Rasmussen stressing correct (danish) pronunciation of important climate events like Allerød and Bølling
Sune Rasmussen stressing correct (danish) pronunciation of important climate events like Allerød and Bølling.

Lead investigator for ice2ice at DMI  Jens Hesselbjerg  taught the students about climate modelling and how to compare ice cores to models and Helle Sørensen from the math department at the University of Copenhagen  introduced basic statistics of time series.

Exercises and laboratory visits were a great opportunity to get hands on experience with real data
Exercises and laboratory visits were a great opportunity to get hands on experience with real data

Two of the days the students got hands-on experience by working in the laboratories; ice2ice PhD Niccolo Maffezoli showed the IC laboratory, where discrete ice samples are analyzed for ions. Professor Thomas Blunier ran an exercise in the gas laboratory where the students breath was analysed similar to ice core samples on a methane Picarro analyser, in the water isotope laboratory postdoc Vasileios Gkinis analysed students own water samples to reproduce the meteoric water line and in the CFA laboratory Marius Simonsen and Helle Kjær had the students prepare and run standards for ammonium. Further the student got hands on experience in annual layer counting led by specialist Mai Winstrup and simple Herron-Langway modelling led by Paul Vallelonga.

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Students busy in the Faxe quarry looking for 64 million year old fossils of the corals that used to be.

To increase the interaction amongst students an excursion to the UNESCO site of Stevns Klint took place in the middle of the week. Stevns Klint is the best place in the world to see the fish clay layer from the extinction 65 million years ago. Also the excursion brought us to Geomuseum Faxe, and Faxe limestone quarry where students retrieved their own 63 million years old fossils. The excursion ended as the best excursions do with beer at a brewery.

The week ended with an official dinner and a few talks.

The course was organised by ice2ice postdoc Helle Astrid Kjær and Assoc. Professor Paul Vallelonga. This year we unfortunately did not have room for all that applied, so we hope to repeat the course next year.