A new paper by Spolaor et al. co-authored by ice2ice associate professor Paul Vallelonga finds that halogens are useful for reconstructing sea ice variability in the Arctic.
Halogens such as brohmine (Br) and Iodine (I) are strongly influenced by sea ice dynamics. Bromine reacts with the sea ice surface and bromine explosion events take place. This causes the brohmine to sodium sea salt to be enhanced. Thus by determining the excess bromine concentration in the ice core relative to the sea salt sodium concentration a signal of the sea ice can be found for the past covered by the ice core.
Similar Iodine is related to sea ice extent. However the Iodine emissions to the polar atmosphere mainly arise from oceanic biological production and is thus related to the presence of ice-free open-ocean conditions.
The Bromine excess was found to correlate well with satellite sea ice area during spring and summer in the Laptev Sea region, while the iodine mainly correlated with the summer sea ice area.
Early January a delayed Christmas package was delivered at Centre for Ice and Climate. The package contained the parts for a “940 Professional IC Vario” from the company Methronohm; an Ion Chromatograph (IC).
The new ion chromatograph, with sample rack and a computer for control and analysis.
The Ion Chromatograph is set up so it offers nM detection of negative ions. These include chloride a sea salt proxy in ice cores, and methane sulfonic acid (MSA) another sea salt proxy. While both these proxies for sea ice are well established in the Southern hemisphere. They have not yet been very successful in the Northern hemisphere, partly because the Greenland ice core samples in which they have been measured to date have been stored for a long time.
We hope that by a short storage time of the ice samples, we can obtain great memeasurements of both MSA and chloride fro the coastal Renland ice core using the new ion chromatograph and determine whether they are useful proxies for sea ice variability in the Arctic over the satellite era. In case they are we hope to use them to infer the sea ice variability in the Arctic further back in time.
Example of raw data obtained from the Ion Chromatograph. Here shown a Renland sample from recent time (bag 11).
Further the ion chromatograph can help us determine the sulfate concentrations in the Renland samples. This is crucial to obtain a great timescale as the sulfate arrive when volcanic eruptions take place. By determining the sulfate levels in multiple cores these can be cross dated, making for accurate comparison between sites.
MSA (methano sulfonic acid). Originates from oxidation of DMS (sea ice algae). Correlates at some Antarctic sites to Sea Ice Extent derived from satellites. Site dependent proxy. Some in situ movement in firn.
Chloride: From winter sea ice, require transport eg. wind affected.
Sulfate: Peak concentrations of sulfate in the ice core are observed when volcanic eruptions have taken place.
A new ice2ice related paper studying the impacts of Arctic sea ice loss is being published in Journal of Climate (currently available as Early Online Release). The paper is authored by ice2ice researchers Rasmus A. Pedersen (NBI/DMI), Peter Langen (DMI) and Bo Vinther (NBI) in collaboration with Ivana Cvijanovic (LLNL, USA).
The analysis is based on general circulation model simulations with CESM in an idealized setup, and investigates the atmospheric response to sea ice loss in different parts of the Arctic.
Three investigated sea ice scenarios with ice loss in different regions all exhibit substantial near-surface warming which peaks over the area of ice loss. The maximum warming is found during winter, delayed compared to the maximum sea ice reduction. The wintertime response of the mid-latitude atmospheric circulation shows a non-uniform sensitivity to the location of sea ice reduction. While all three scenarios exhibit decreased zonal winds related to high-latitude geopotential height increases, the magnitudes and locations of the anomalies vary between the simulations.
The location of the wintertime (DJF) NAO centers of action are illustrated through the location of the ten highest and ten lowest values of the leading EOF from 500 bootstrap samples. Contours show the total number occurrences in each grid cell combining all bootstrap samples: CTRL (pre-industrial ice cover) in black, ARC (ice loss across entire Arctic) in red, ATL (ice loss in the Atlantic sector of the Arctic) in green and PAC (ice loss in the Pacific sector of the Arctic) in blue. The contour interval is 50 counts with the lowest contour at 50.
Investigation of the North Atlantic Oscillation reveals a high sensitivity to the location of the ice loss. The northern center of action exhibits clear shifts in response to the different sea ice reductions. Sea ice loss in the Atlantic and Pacific sectors of the Arctic cause westward and eastward shifts, respectively.
The CFA melting campaign of the Renland ice core started mid-October at the Centre for Ice and Climate (CIC) in Copenhagen. Paul H. and Andreas from Bergen visited the lab early in the campaign and saw first-hand how an ice core is prepared and analyzed. Below is their explanation of the continuous flow analysis ice core lab.
The people at the CFA work in two shifts from 8-14 and from 14-until closing time. During a normal day approximately 16m of ice is being melted. The first part of the work begins in the “warm” freezer at -15°C. The cores are stored in an even colder freezer. So for this work you better pack yourself better than Paul did on his first day.
The ice cores are stored in 55cm long pieces; ideally if there are no breaks in between. To get a square-shaped core that fits into the melting frame, part of the core is cut again. Paul V. is showing the newcomer how it is done.
After that the filled melting frames are put in a freezer in the lab where they are melted via the so-called melt head.
The melt rate is governed by the temperature of the melt head. You can nicely see the air bubbles within the ice.
Then the melted ice is separated into a lots of little streams, both gaseous and liquid. The “gas people” measure stable water isotopes (delta_18O, delta_17O, delta_D) as temperature proxies and methane employing laser mass-spectrometry. The “liquid people” measure the sum of all dust, calcium, iron, conductivity, pH, NH4+, sodium, and black carbon, either using direct absorption or fluorescence. All these measurements are done from the continuous sample stream.
So let’s take a quick look at the lab. Paul watching the ice core has plenty of time to check emails.
The main screen of the liquid part measurements.
Finally the first part of the black carbon detector is Ross-approved.
Besides all the science, Copenhagen also offers nice sunsets, fantastic cycling, and a great bakery across from the apartment. We limited ourselves to one kanelsnulle per day.
We started to get an appreciation for the astounding amount of work and attention that goes into producing each time series from an ice core. Many thanks to our hosts in Copenhagen for spending the time teaching and talking with us.
The Norwegian state broadcaster NRK news program, Urix , followed one of the Principal investigators in the Ice2Ice project, Kerim Hestnes Nisancioglu on a cruise to the West coast of Greenland.
The Ice2Ice project was well highlighted as the program In the program Kerim explained the risks of rapid and increasing ice melting in Greenland. The TV-team documented as temperature data from the fjord was analysed at the Danish research station at Greenland, showing the surprising result of a fjord temperature of as much as three and a half degrees.
Nice to have a look in the microscope. Photo: Evangeline Sessford.
Uni Research and the Bjerknes Centre for Climate Research ensured a popular stand during UNG 2015, organised by Forskningsdagene. The theme of the week was food, so Ice2Ice decided to put the climate archive on the dinner table.
Ocean water, sediment cores and volcanic ash were some of the ingredients on Ice2Ice’s menu. Around thirty-five curious high-school students seized the opportunity to ask questions and have a look in the microscope. A poster explained different ways of measuring sea temperature, salinity and sea ice. The students got to learn about methods, which are used to obtain knowledge about climate back in time. Since it is not possible to make direct measurements of temperature from earlier times, one has to use the geological archive to get the information needed.
Knowledge about the past sea-ice extent is very important to us for several reasons. For exemple, it is necessary for us to find out how temperature, salinity and sea-ice have varied in the past to be able to tell how these are going to behave in the future. We can make comparisons between the proxy or old data and instrumental data from today to discover changes and we can use this to test climate models.
The students had the opportunity to have a closer look at the different depths in a marine sediment core recovered from off eastern Greenland. However, the Ice2Ice team did not stop there: students were also allowed to taste the different layers. By tasting the sediment core, they noticed whether the consistency was “toothpaste” or “crunchy” and were further able to tell what parts the sediment core was made of: the clay is like toothpaste and contain only very small grains while the silt is more coarse and crunchy. The microscope was useful to distinguish the different types of foraminifera: which in short is tiny plankton with hard shell less than 1 mm big. Particles of sand and minerals were identified and the students also got to learn about the Ice2Ice’s cruise from this summer.
Happy Ice2Ice team members on stand: Evangeline Sessford, Henrik Sadatzki, Ida Olsen and Margit Simon. Photo credit: Evangeline Sessford
Evangeline Sessford together with colleagues Henrik Sadatzki, Margit Simon and Ida Olsen from the Ice2Ice team organised and manned the research stand. Evangeline says that to most of the students this was new knowledge.
– The students enjoyed looking in the microscope, as most of them never had tried that before. I think they felt a bit of pride when they managed to identify the correct species from the poster as the one they were looking at in the microscope. They were also quite intrigued that the size of the sediment could tell so much about current, and that you could actually taste it to tell the difference.
The students were curious about why the researchers need information about past temperatures.
– Knowing how the oceans were in the past during periods of warmer climate can shred light on what may happen in the future with concerns about global warming.
Last week several nations met at the danish science society to discuss in more details the plan for the EastGRIP ice core drilling project. The project focuses on the North East Greenland Ice Stream. Several ice2ice members are also part of the EastGRIP project including lead PIs of ice2ice Eystein Jansen (N), Bo Vinther (DK) and Kerim Hestnes (DK)
Several danish news blogs picked up on the information amongst them the danish national television that had a 6 minutes long interview with lead scientist of the EGRIP project Dorte Dahl-Jensen (link-aprox 25 minutes in).
Twenty scientists gathered in Copenhagen at the end of October 2015 to discuss the most recent isotope model developments and the most recent scientific understanding and interpretation of the d18O changes recorded in Greenland during the last deglaciation.
The cryosphere is in fast transition and there is the possibility that the ongoing rapid demise of Arctic sea ice may instigate abrupt changes on the Greenland Ice Sheet. Ice cores here show clear evidence of past abrupt warm events with up to 15°C warming in less than a decade, most likely triggered by rapid changes in Arctic sea ice.
These results rely heavily on oxygen isotope data, which is a key climate proxy from ice cores as well as marine sediment cores. Over the last two decades there have been a number of studies with climate models investigating the possible mechanisms behind these large changes in climate. However, comparing reconstructed climate as recorded by the oxygen isotope record with the physical climate as given by the numerical models is a challenge.
The group focused on future research priorities to answer some key questions:
How can models help us better understand the rapid changes in d18O?
How changes in local and non-local processes play a role in affecting the d18O recorded over Greenland during rapid abrupt cooling events?
What are the biggest uncertainties and challenges in the isotope modelling community?
Additional key questions were:
What was the role of sea-ice cover in affecting the d18O recorded during the D-O events?
How the changes in sea-ice extent affect the origin of moisture delivered over Greenland?
Sensitivity studies exploring the above-mentioned aspects might be model dependent. Hence, it is important to investigate them in a multimodel framework. For this reason, a set of sensitivity studies with common boundary conditions has been defined and they will be run by 4 different modelling groups (CESM, GISS, ECHAM, HadGEM (?)). The results of these simulations will then be discussed in a future workshop within the Ice2ice project.
Author: Francesco S. R. Pausata, Department of Meteorology and Bolin Centre for Climate Research, Stockholm University, Stockholm, Sweden; email: francesco.pausata@misu.su.se
A bootcamp for the ice2ice PhDs took place in Nothern Sealland, Denmark. 17 phd’s and 5 mentors participated in the workshop that lasted 5 days. Below a report from the Phd’s.
Day 1. Monday, September 28th
From Copenhagen, we drove 1.5 hrs to Anneberg hostel on Nord-Sjælland, where we would spend the whole week. Following a group lunch, we made a quick introduction round and started right away with short presentations of the three workshop groups:
Ocean temperature during Dansgaard–Oeschger (DO) events – DO dynamics debated; simulation of full DO cycle challenging – proxy surrogate method – model data pool vs. proxy data pool (resolution 1-2 degrees) – model run that fits proxy data – spatial consistency?
Sea Ice and Greenland accumulation – How is sea ice influencing accumulation on Greenland? Spatial correlation between sea ice and accumulation; investigate influence of delay; investigate possible mechanisms for accumulation-sea ice connection
Inverse modeling of ice shelves – explicit focus on method (inversion – i.e. invert surface velocity fields for viscosity or basal friction to best fit observed velocities) – inverse theory + real world experiments in Antarctica (no present-day ice shelves in Greenland)
Photo credit:Henning Åkeson
The introduction of the workshop groups was followed by our first science talk by Camille Li. Camille gave a quick introduction to the climate system and how to come from the real world to a climate model.
Day 2. Tuesday, September 29th
The morning started with a science talk by Chris Borstad, who talked about changes in ice shelf rheology.
Afterwards, the group work started with a meeting with the mentors, and the session lasted until dinner. The evening consisted of a data visualization workshop. Here Aleksi showed different approaches to plot flow patterns when making geographic maps. Camille Li showed plots from her contribution to the IPCC (2014) report about temperature and precipitation response to freshwater hosing (8.2 ka event). Henning talked about color graphics in plotting, and introduced a MATLAB function that always created the most distinguishable colors when plotting. Chris talked about how the choice of colormap should depend on the data, and why the color scale can perceive the reader.
Day 3. Wednesday, September 30th
After group work sessions in the morning we went on a field trip to the Geopark Odsherred in the afternoon to learn about the regional cultural and geological background of eastern Denmark. The field trip included visits of two barrows from the Stone Age and Bronze Age as well as an easy hike on one of the highest ’mountains’ in Denmark, the 121 m high mound Vejrhøj. The hilly landscape was largely shaped during the last glacial when advancing and retreating glaciers led to the formation of moraines, meltwater outlets and proglacial lakes.
Photo credit:Henning Åkeson
In the evening Bjørg Risebrobakken gave a science talk about proxies in paleoceanography and their possibilities and limitations.
Day 4. Thursday, October 1st
This day was filled with intense group work, preceded by Andreas Born’s talk on the Influence of ice sheet topography and sea ice cover on Eemian Greenland temperature and precipitation.
The group work focused on:
Background info on Eemian
Simulations of atmospheric effects on Greenland during Eemian
Precipitation changes (using site of today’s NEEM during Eemian)
Photo credit:Henning Åkeson
Day 5. Friday, October 2nd
The final day involved some intense finalization of the three group projects. Findings were presented after lunch. They main findings were
1) Ocean temperature during Dansgaard–Oeschger (DO) events – The proxy surrogate method has great potential for combining proxy records with model simulations. According to the model runs, the temporal variability of the Nordic Seas and northern North Atlantic can be explained well by the proxy sites available. However, information from eastern Greenland/close to Fram Strait is lacking, and proxy reconstructions from this area would be highly valuable. Spatial maps of sub-surface temperatures from DO event 7, and a constructed idealized DO event, were made. The results were quite sensitive to small changes in the reconstructed sub-surface temperature values. This needs to be investigated further. The results were limited by the little variability in the model run compared to observations.
2) Sea Ice and Greenland accumulation – The correlations patterns between sea ice and accumulation and δ18O data for NEGIS/EGRIP showed that it was difficult to determine the cause of correlations (co-causality problem). The correlation results were not consistent with the NAO pattern driving changes in sea ice and δ18O. However, lower elevation and near-coastal ice cores (Camp Century, Renland, ATC10) were more sensitive to local sea ice conditions.
3) Inverse modeling of ice shelves – Inversion results (for Pine Island Glacier, W. Antarctica) are sensitive to initial guess of the parameter we want to invert for (ice shelf: rheology; grounded ice: basal friction). Form of cost function (absolute/logarithmic/average misfit) renders slightly different results. Also wanted to test how incomplete spatial data coverage affect inversions, but some model technicalities prevented final conclusions here.
The final presentations marked the formal end of the bootcamp. Participants were afterwards witnessing how to skin a deer (hunting season just started the same day) and joined for mushroom picking in the forest nearby. The deer and mushrooms ended up on the grill and in a sauce, and finally on participants’ plates.
Photo credit:Henning Åkeson
Most people thought that the bootcamp was very relevant to their own PhD research, and that they would like to see another such event in the future, in the same or slightly different format.
author: Henning Åkeson on behalf of the ice2ice PhD’s
The 15th Karthaus summer school on Ice Sheets and Glaciers in the Climate System took place from 8th to 19th September 2015 in Karthaus (Bolzano, Italy) on the Italian alps. The course provided knowledges on various aspects of glaciers and ice sheets to Ph.D. students that work on a glaciology-related climate project. Topics included continuum mechanics, kinematics, ice rheology, sliding and hydraulics, numerical modelling, polar meteorology, ice-ocean interaction, ice cores, interaction of ice sheets with the solid earth, glacier fluctuations, and much more-all related to the ice2ice project.
The participants of the 2015 Karthaus Summer
During nearly two weeks, a total of 36 students attended lectures in the morning and exercises in the afternoon. Computer projects, done in groups of three students, was also part of the summerschool programme. The projects were in the end presented to the class. An excursion to the nearby glaciers was also organized, to observe in reality the different aspects of the glacial environment.
Alpine passes are marked with crosses since the XIII century.Excursion to a nearby glacier
