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Cryospheric Sciences

Antarctica

Image of the Week – Ice Ice Bergy

Image of the Week – Ice Ice Bergy

They come in all shapes, sizes and textures. They can be white, deep blue or brownish. Sometimes they even have penguins on them. It is time to (briefly) introduce this element of the cryosphere that has not been given much attention in this blog yet: icebergs!


What is an iceberg?

Let’s start with the basics. An iceberg, which literally translates as “ice mountain”, is a bit of fresh ice that broke off a glacier, an ice shelf, or a larger iceberg, and that is now freely drifting in the ocean. As an approximation, you can consider that since an iceberg is already in the water (about 90% under water even), its melting does not contribute to sea-level rise. However, if you remember our Sea Level “For Dummies” post, you know that the melting of fresh ice reduces the ocean’s density and makes it expand. Icebergs are found at both poles, although they tend to be larger in the Southern Ocean. The largest iceberg ever spotted there was 335 by 97 km, which represents an area larger than Belgium !

Modelled trajectories of icebergs around Antarctica. The different colours represent different size classes, ranging from 0-1 km² (class 1) to 100-1000 km² (class 5). [Credit: subset of Fig 2 from Rackow et al (2017)]

Icebergs can drift over thousands of kilometres (Rackow et al., 2017), during several years. A more thorough account of the life of an iceberg will be given in a future post, but be aware that among other things, as it drifts:

  • The iceberg is eroded by the waves and melted by the relatively warm ocean;
  • It can split in several pieces because of this melting and mechanical stress;
  • Sea ice can freeze around it, trapping it in the pack ice.

This means that the iceberg changes shape a lot, and can be tricky to monitor (Mazur et al, 2017).

Why do we want to monitor icebergs?

You may have heard of the Titanic, and hence are aware that icebergs pose a risk for navigation not only in the polar regions but even in the North Atlantic. Icebergs also are large reservoirs of freshwater, and depending on how and where they melt, this inflow of melted freshwater can really affect the ocean; it even dominates the freshwater budget in some Greenland fjords (Enderlin et al., 2016).

Icebergs have traditionally been rather understudied, so we are only now discovering how important they are and how they interact with the rest of the climate system: increasing sea ice production (A. Mazur, PhD thesis, 2017), biological activity (Vernet et al., 2012), and even carbon storage (Smith et al., 2011). And sometimes, they have penguins on them!

All eyes in the CryoTeam are now turned to the Antarctic Peninsula, where a giant iceberg may detach from the Larsen C ice shelf soon. To learn how we know that, check this video made by ESA. And of course, continue reading us – we’ll be reporting about the birth of this monster berg!

An iceberg by Antarctica [Credit: C. Heuzé]

Edited by Sophie Berger

Further reading

  • Enderlin et al. (2012), Iceberg meltwater fluxes dominate the freshwater budget in Greenland’s iceberg-congested glacial fjords, Geophysical Research Letters, doi:10.1002/2016GL070718

  • Mazur et al. (2017), An object-based SAR image iceberg detection algorithm applied to the Amundsen Sea, Remote Sensing of Environment, doi:10.1016/j.rse.2016.11.013

  • Rackow et al. (2017), A simulation of small to giant Antarctic iceberg evolution: Differential impact on climatology estimates, Journal of Geophysical Research: Oceans, doi: 10.1002/2016JC012513
  • Smith et al. (2011), Carbon export associated with free-drifting icebergs in the Southern Ocean, Deep Sea Research, doi: 10.1016/j.dsr2.2010.11.027
  • Vernet et al. (2012), Islands of Ice: Influence of Free-Drifting Antarctic Icebergs on Pelagic Marine Ecosystems, Oceanography, doi:10.5670/oceanog.2012.72

Image of the Week – Antarctica’s Flowing Ice, Year by Year

Fig 1: Map series of annual ice sheet speed from Mouginot et al. (2017). Speeds range from 0 (purple) to 1000+ (dark brown) m/yr. [Credit: George Roth]

Today’s Image of the Week shows annual ice flow velocity mosaics at 1km resolution from 2005 to 2016 for the Antarctic ice sheet. These mosaics, along with similar data for Greenland (see Fig.2), were published by Mouginot et al, (2017) last month as part of NASA’s MEaSUREs (Making Earth System Data Records for Use in Research Environments) program.


How were these images constructed?

The mosaics shown today (Fig 1 and 2) were built by combining optical imagery from the Landsat-8 satellite with radar (SAR) data from the Sentinel-1a/b, RADARSAT-2, ALOS PALSAR, ENVISAT ASAR, RADARSAT-1, TerraSAR-X, and TanDEM-X sensors.

Although the authors used the well-known techniques of feature and speckle tracking to produce their velocities from optical and radar images, respectively, the major novelty of their study lies in the automation and integration of the different datasets.

Fig.2: Mosaics of yearly velocity maps of the Greenland and Antarctic ice sheet for the period 2015-2016.Composite of satellite-derived yearly ice sheet speeds from 2005-2016 for both Greenland and Antarctica. [Credit: cover figure from Mouginot et al. (2017)]

How is this new dataset useful?

Previously, ice sheet modellers have used mosaics composed of satellite data from multiple years to cover the entire ice sheet. However, this new dataset is one of the first to provide an ice-sheet-wide geographic scale, a yearly temporal resolution, and a moderately high spatial resolution (1km). This means that modellers can now better examine how large parts of the Greenland and Antarctic ice sheets evolve over time. By linking the evolution of the ice sheets to the changes in weather and climate over those ice sheets during specific years, modellers can calibrate the response of those ice sheets’ outlet glaciers to different climate conditions. The changes in the speeds of these outlet glaciers have important consequences for the amount of sea level rise expected for a given amount of warming.

How can I start using this data?

The yearly MEaSUREs data is hosted at the NSIDC in NetCDF format. The maps shown in the animated image were made using Quantarctica/QGIS (for more information on Quantarctica, check out our previous post E). QGIS natively supports NetCDF files like these mosaics with no additional import steps. Users can quickly calculate new grids showing speed, changes in velocities between years, and more by using the QGIS Raster Calculator or gdal_calc.

References/ Further Reading

Mouginot, J., Rignot, E., Scheuchl, B., & Millan, R. (2017). Comprehensive Annual Ice Sheet Velocity Mapping Using Landsat-8, Sentinel-1, and RADARSAT-2 Data. Remote Sensing, 9(4), 364. http://dx.doi.org/10.3390/rs9040364

Image of the Week – Quantarctica: Mapping Antarctica has never been so easy!

Image of the Week – A high-resolution picture of Greenland’s surface mass balance

Written with help from Jelte van Oostsveen
Edited by Clara Burgard and Sophie Berger


George Roth is the Quantarctica Project Coordinator in the Glaciology group (@NPIglaciology) at the Norwegian Polar Institute. He has spent the last several years helping researchers with GIS, cartography, and remote sensing in both the Arctic and Antarctic.

A year at the South Pole – an interview with Tim Ager, Research Scientist

A year at the South Pole – an interview with Tim Ager, Research Scientist

What is it like to live at the South Pole for a year?  A mechanical engineer by trade, Tim Ager, jumped at the opportunity to work for a year as a research scientist at Amundsen-Scott South Pole Station.  When not traveling on various adventures he lives in Austin, Texas, and recently took the time to answer a few questions about his time at Pole.


What goes on at Amundsen-Scott South Pole Station?

Science!  And lots of it.  Of course there are many people working at Pole just to maintain operations and “keep the lights on,” but it is all in support of science.  There are several large-scale science projects.  A couple highlights that science grantees taught us during science lectures were:

  • The South Pole Ice Core (SPICE Core) project looks back in time into the history of earth through ice cores.  Every year, snow accumulates on the surface, and year after year these layers compress the snow below them into ice.  By drilling down and extracting ice cores, these layers can be studied much like the tree rings.  The ice itself is analyzed, but so are the chemicals, dust, and gas bubbles trapped in it. This analysis gives us a peek into the climate history of our planet (see this post for more details).  Last summer’s project goal of drilling down 1,500 meters (to ice approximately 40,000 years old) was easily surpassed, with the final ice core brought up from a depth of 1,751.5 meters.
  • There are three Cosmic Microwave Background telescopes at Pole that look back in time at the oldest light in the universe, which was created shortly after the big bang.  The South Pole’s near 0% humidity is the ideal place to do this, since the telescopes look for slight ripples of temperature variations in the light and any water vapor gets in the way.
  • IceCube, which is a 1 km³ telescope that sites on the South Pole and collect neutrinos, which are tiny electrically neutral particles that can provide insight into the processes that occur within the sun.  The telescope collects neutrinos that pass through the Earth, which acts like a big filter, and collects only 3 per day.
  • Other projects include studying the weather, the magnetosphere, and ozone depletion.

Inside the collector of the 10 m South Pole Telescope  [Credit: Tim Ager]

Can you tell us a bit about the projects you were working on and what a typical day was like at the station?

I was a caretaker for several projects.  I maintained two GPS projects that tracked the movement of the ice sheet the South Pole Station sits on.  This huge chunk of ice moves about 10 meters per year toward the Weddell Sea.  For the six months that the sun was down I maintained seven aurora cameras.  I was also responsible for SPRESSO (the South Pole Remote Earth Science and Seismological Observatory).  SPRESSO is a seismic listening station for the long-term study of seismicity at the South Pole. It is a part of a 120+ station Global Seismographic Network (GSN) and is located five miles from the South Pole Station to reduce station related “cultural” noise. SPRESSO is located within our “quiet sector” and is the quietest seismic listening post on the planet.  Some additional duties included maintaining the greenhouse, acting as the station cryotech (making and dispensing liquid nitrogen), and testing fuel.

During the summer season there wasn’t a typical day, and I was kept busy helping many science related activities run efficiently.  The typical grantee is only at Pole for one to two weeks, so their time there is very valuable.  Before a grantee arrived, I tracked down any cargo they had sent ahead and made sure any crates that weren’t supposed to freeze were not left outside.  Once the grantee arrived, I helped out with whatever they needed to ensure their visit was a success – from finding and digging out a drifted-over crate left outside several years earlier, to tracking down tools, to delivering liquid nitrogen.  It was never boring and gave me the opportunity to learn about numerous projects.

Amundsen-Scott Station at sunset with markers to help traveling to off-station sites [Credit: Tim Ager]

What did you do when you weren’t working?

There was so much to do that I often had to choose between more than one activity.  There is a weight room, a gymnasium, a sauna, a quiet reading room (filled with lots of books), a game room (with a pool table, foosball table, and even more books), a music room (filled with instruments), an art room (filled with cloth, yarn, paints, markers, colored pencils, paper, sewing machines, and who knows what else), a greenhouse, and two media rooms (filled with DVDs of movies and TV shows, video games, VHS tapes, and even Beta Max tapes – yes, Pole has a working Beta Max player).  People taught classes on a variety of subjects including music, Yoga, particle physics, astronomy, welding, and foreign languages, to name a few.  I learned to play the guitar and became fairly proficient at knitting.

How were the 6 months of darkness and the frigid temperatures?

And the cold wasn’t as uncomfortable as you would think – when you get used to dressing appropriately, -100°F [-75°C] is okay.

The six months of darkness were amazing.  It is hard to explain the magnificence of the night sky.  Given the extremely low humidity at Pole, we could view the stars with unusual clarity, and the aurora activity was nearly constant.  In fact, the auroras frequently obscured the view of the stars, which wasn’t a bad trade-off.  And the cold wasn’t as uncomfortable as you would think – when you get used to dressing appropriately, -100°F [-75°C] is okay.

One of many auroras from the South Pole [Credit: Max Peters]

Was there a big shift in the culture of the station between the summer and the winter?

Yes, the summer and winter seasons are completely different.  During the summer season (usually early November thru mid-February) there is a flurry of activity.  Planes are coming and going, people are coming and going, and the station is full with 150 – 170 people.  Because the summer season is relatively short, everyone is focused on getting as much done as possible.  But once the last plane leaves everything slows down.  The remaining station members put the finishing touches on winterizing the station and settle into a routine that won’t change much, day in and day out, for 8.5 months.

The last plane out doing its customary goodbye flyover – “no one in and no one out” for 8.5 months [Credit: Tim Ager]

Could you share with us any moments that you’ll never forget?  What moments stick out as the highlights of your trip?

The day the last plane of the summer season left was unforgettable.  No matter how well you think you’ve prepared, it is a moment that is extremely unique.  That is when the reality of the situation and the isolation really sinks in.  The remaining 48 of us looked around at each other and pretty much all had the same thought: “Well, this is it.  This is my family for the next 8.5 months.  No one in and no one out.”  Of course we didn’t know that we would have a medevac [i.e., a medical evacuation] in the middle of winter – only the third winter medevac ever, and the first time in total darkness.  It went smoothly and left 46 of us for the rest of the winter.

Although there were many amazing experiences, the highlight was the night sky.  The stars were incredible, and the nearly ever-present auroras were awe inspiring.

I would also like to say that we had an incredible winter-over crew.  People were responsible, hard workers, and always willing to lend a hand.  Although we were all ready to leave once winter was over, I miss the camaraderie of my South Pole family.

The 2016 winterover crew [Credit: Tim Ager]

To conclude is there anything you would like to say to any future winter-overs?

If you have the time and inclination, definitely consider a winter at Pole.  At times it can be physically and/or psychologically challenging, but if you embrace it and live in the moment every day, the time will fly by.  We were all amazed at how quickly it was over.  I am thankful for the opportunity, and often find myself daydreaming about living back at Pole.

Interview led by David Rounce  and edited by Sophie Berger

Image of the Week — Hidden lakes in East Antarctica !

Image of the Week — Hidden lakes in East Antarctica !

Who would have guessed that such a beautiful picture could get you interviewed for the national news?! Certainly not me! And yet, the photo of this englacial lake (a lake trapped within the ice in Antarctica), or rather science behind it, managed to capture the media attention and brought me, one of the happy co-author of this study,  on the Belgian  television… But what do we see on the picture and why is that interesting?


Where was the picture taken?

The Image of this Week shows a 4m-deep meltwater lake trapped 4 m under the surface of the Roi Baudouin Ice Shelf (a coastal area in East Antarctica). To capture this shot, a team of scientists led by Stef Lhermitte (TU Delft) and Jan Lenaerts (Utrecht University) went to the Roi Baudouin ice shelf, drilled a hole and lowered a camera down (see video 1).

Video 1 : Camera lowered into borehole to show an englacial lake 4m below the surface. [Credit: S. Lhermitte]

How was the lake formed?

In this region of East Antarctica, the katabatic winds are very persistent and come down from the centre of the ice sheet towards the coast, that is the floating ice shelf (see animation below). The effect of the winds are two-fold:

  1. They warm the surface because the temperature of the air mass increases during its descent and the katabatic winds mix the very cold layer of air right above the surface with warmer layers that lie above.
  2. They sweep the very bright snow away, revealing darker snow/ice, which absorb more solar radiation

The combination leads to more melting of the ice/snow in the grounding zone — the boundary between the ice sheet and ice shelf — , which further darkens the surface and therefore increases the amount of solar radiation absorbed, leading to more melting, etc. (This vicious circle is very similar to the ice-albedo feedback presented in this previous post).

Animation showing the processes causing the warm micro-climate on the ice shelf. [Credit: S. Lhermitte]

All the melted ice flows downstream and collects in depressions to form (sub)surface lakes. Those lakes are moving towards the ocean with the surrounding ice and are progressively buried by snowfalls to become englacial lakes. Alternatively, the meltwater can also form surface streams that drain in moulins (see video 2).

Video 2 : Meltwater streams and moulins that drain the water on the Roi Baudouin ice shelf. [Credit: S. Lhermitte]

Why does it matter ?

So far we’ve seen pretty images but you might wonder what could possibly justify an appearance in the national news… Unlike in Greenland, ice loss by surface melting has  often been considered negligible in Antarctica. Meltwater can however threaten the structural integrity of ice shelves, which act as a plug of the grounded ice from upstream. Surface melting and ponding was indeed one of the triggers of the dramatic ice shelves collapses in the past decades, in the Antarctic Peninsula . For instance, the many surfaces lakes on the surface of the Larsen Ice shelf in January 2002, fractured and weakened the ice shelf until it finally broke up (see video 3), releasing more grounded ice to the ocean than it used to do.

Of course surface ponding is not the only precondition for an ice shelf to collapse : ice shelves in the Peninsula had progressively thinned and weakened for decades, prior their disintegration. Our study suggests however that surface processes in East Antarctica are more important than previously thought, which means that this part of the continent is probably more vulnerable to climate change than previously assumed. In the future, warmer climates will intensify melt, increasing the risk to destabilise the East Antarctic ice sheet.

Video 3 : MODIS images show Larsen-B collapse between January 31 and April 13, 2002. [Credit:NASA/Goddard Space Flight Center ]

Reference/Further reading

Edited by Nanna Karlsson

Quantarctica: Mapping Antarctica has never been so easy!

Quantarctica: Mapping Antarctica has never been so easy!

One of the most time-consuming and stressful parts of any Antarctic research project is simply making a map. Whether it’s plotting your own data points, lines, or images; making the perfect “Figure 1” for your next paper, or replying to a collaborator who says “Just show me a map!,” it seems that quick and effective map-making is a skill that we take for granted. However, finding good map data and tools for Earth’s most sparsely-populated and poorly-mapped continent can be exhausting. The Quantarctica project aims to provide a package of pre-prepared scientific and geographic datasets, combined with easy-to-use mapping software for the entire Antarctic community. This post will introduce you to Quantarctica, but please note that the project is organizing a Quantarctica User Workshop at the 2017 EGU General Assembly (see below for more details).


[Credit: Quantarctica Project]

What is Quantarctica?

Quantarctica is a collection of Antarctic geographic datasets which works with the free, open-source mapping software QGIS. Thanks to this Geographic Information System package, it’s now easier than ever for anyone to create their own Antarctic maps – for any topic and at any spatial scale. Users can add and plot their own scientific data, browse satellite imagery, make professional-quality maps and figures, and much, much more. Read on to learn how researchers are using Quantarctica, and find out how to use it to start making your own (Qu-)Antarctic maps!

Project Origins

When you make a sandwich, you start with bread, not flour. So why would you start with ‘flour’ to do your science?” — Kenny Matsuoka, Norwegian Polar Institute

Deception Island isn’t so deceptive anymore, thanks to Quantarctica’s included basemap layers, customized layer styles, and easy-to-use cartography tools. [Credit: Quantarctica Project]

Necessity is the mother of invention, and people who work in Antarctica are nothing if not inventive. When Kenny Matsuoka found himself spending too much time and effort just locating other Antarctic datasets and struggling with an expired license key for his commercial Geographic Information System (GIS) software in the field, he decided that there had to be a better way – and that many of his Antarctic colleagues were probably facing the same problems. In 2010, he approached Anders Skoglund, a topographer at the Norwegian Polar Institute, and they decided to collaborate and combine some of the critical scientific and basemap data for Antarctica with the open-source, cross-platform (Windows, Mac, and Linux) mapping software QGIS. Quantarctica was born, and was quickly made public for the entire Antarctic community.

Since then, maps and figures made with Quantarctica have appeared in at least 25 peer-reviewed journal articles (that we can find!). We’ve identified hundreds of Quantarctica users, spread among every country participating in Antarctic research, with especially high usage in countries with smaller Antarctic programs. We’ve been actively incorporating even more datasets into the project, teaching user workshops at popular Antarctic conferences – such as EGU 2017 – and building educational materials on Antarctic mapping for anyone to use.

A great example of a Quantarctica-made figure published in a paper. Elevation, imagery , ice flow speeds, latitude/longitude graticules, custom text and drawing annotations… it’s all there and ready for you to use! [Credit: Figs 1 and 2 from Winter et al (2015)].

What data can I find in Quantarctica?

  • Continent-wide satellite imagery (Landsat, MODIS, RADARSAT)
  • Digital elevation models and/or contour lines of bed and ice-surface topography and seafloor bathymetry
  • Locations of all Antarctic research stations and every named location in Antarctica (the SCAR Composite Gazetteer of Antarctica)
  • Antarctic and sub-Antarctic coastlines and outlines for exposed rock, ice shelf, and subglacial lakes
  • Magnetic and gravity anomalies
  • Ice flow velocities, catchment areas, mass balance, and firn thickness grids
  • Ancient UFO crash sites

…just to name a few!

Four examples of included datasets. From left to right: Ice flow speed, drainage basins, and subglacial lakes; bed topography; geoid height; modeled snow accumulation and surface blue ice areas [Credit: Quantarctica Project]

All of these datasets have been converted, imported, projected to a standard Antarctic coordinate system, and hand-styled for maximum visibility and compatibility with other layers. All you have to do is select which layers you want to show! The entire data package is presented in a single QGIS project file that you can quickly open, modify, save, and redistribute as your own. We also include QGIS installers for Windows and Mac, so everything you need to get started is all in one place. And finally, all of the data and software operates entirely offline, with no need to connect to a license server, so whether you’re in a tent in Antarctica or in a coffee shop with bad wi-fi, you can still work on your maps!

Quantarctica was used in traverse planning for the MADICE Project, a collaboration between India’s National Centre for Antarctic and Ocean Research (NCAOR) and the Norwegian Polar Institute (NPI), investigating mass balance, ice dynamics, and climate in central Dronning Maud Land. Check out pictures from their recently-completed field campaign on Facebook and Twitter! Base image: RADARSAT Mosaic; Ice Rises: Moholdt and Matsuoka (2015); Mapping satellite features on ice: Ian Lee, University of Washington; Traverse track: NCAOR/NPI. [Credit: Quantarctica Project]

Every dataset in Quantarctica is free for non-commercial use, modification, and redistribution – we get explicit permission from the data authors before their datasets are included in Quantarctica, always include any README or extra license/disclaimer files, and never include a dataset if it has any stricter terms than that. We always provide all metadata and citation information, and require that any Quantarctica-made maps or figures printed online or in any publication include citations for the original datasets.

How do I start using Quantarctica?

Quantarctica is available for download at http://quantarctica.npolar.no/. It’s a 6 GB package, so if your internet connection is struggling with the download, just contact us and we can send it to you on physical media. You can use the bundled QGIS installers for your operating system, or download the latest version of QGIS at http://qgis.org/ and simply open the Quantarctica project file, Quantarctica.qgs, after installation.

We’re actively developing Version 3 of Quantarctica, for release in Late 2017. Do you know of a pan-Antarctic dataset that you think should be included in the new version? Just email the Quantarctica project team at quantarctica@npolar.no.

Quantarctica makes it easy to start using QGIS, but if you’ve never used mapping software before or need to brush up on a few topics, we recommend QGIS Tutorials and Tips and the official QGIS Training Manual. There are also a lot of great YouTube tutorial videos out there!

 

Nobody said you could only use Quantarctica for work – you can use it to make cool desktop backgrounds, too! Foggy day in the Ross Island / McMurdo Dry Valleys area? Though it often is, the fog effects image was created using only the LIMA 15m Landsat Imagery Mosaic and RAMP2 DEM in Quantarctica, with the help of this tutorial. [Credit: Quantarctica Project]

Quantarctica Short Course at EGU 2017

Are you attending EGU 2017 and want to learn how to analyze your Antarctic data and create maps using Quantarctica? The Quantarctica team will be teaching a short course (SC32/CR6.15) on Monday, 24 April at 13:30-15:00 in room -2.31. Some basic GIS/QGIS experience is encouraged, but not required. If you’re interested, fill out the registration survey here: https://goo.gl/forms/mLaJg686tZq8bm2N2 and feel free to send any questions or comments to quantarctica@npolar.no. We’ll see you in Vienna!

Edited by Kenny Matsuoka and Sophie Berger

Reference/Further Reading

Data sources

[Read More]

Image of the Week – Apocalypse snow? … No, it’s sea ice!

Image of the Week – Apocalypse snow? … No, it’s sea ice!

Sea ice brine sampling is always great fun, but sometimes somewhat challenging !

As sea water freezes to form sea ice, salts in the water are rejected from the ice and concentrate in pockets of very salty water, which are entrapped within the sea ice. These pockets are known as “brines”.

Scientists sample these brines to measure the physical and bio-geochemical properties, such as: temperature, salinity, nutrient, water stable isotopes, Chlorophyll A, algal species, bacterial number and DNA, partial pressure of CO2, dissolved and particulate Carbon and Nitrogen, sulphur compounds, and trace metals.  All of this helps to better understand how sea ice impacts the atmosphere-ocean exchanges of climate relevant gases.

In theory, sampling such brines is very simple: you just have to drill several holes in the sea-ice ensuring that the holes don’t reach the bottom of ice and wait for half an hour. During this time, the brine pockets which are trapped in the surrounding sea ice drain under gravity into the hole. After that, you just need to sample the salty water that has appeared in the hole. Simple…

…at least it would be if they didn’t have to deal with the darkness of the Antarctic winter, blowing snow, handling water at -30°C and all while wearing trace metal clean suits on top of polar gear…hence the faces!


This photo won the jury prize of the Antarctic photo competition, organised by APECS Belgium and Netherlands as part of Antarctica Day celebrations (1st of December).

All the photos of the contest can be seen here.

Edited by Sophie Berger and Emma Smith


Jean-Louis Tison is a professor at the Université libre de Bruxelles. His activities are focused on the study of physico-chemical properties of « interface ice », be it the « ice-bedrock » (continental basal ice) , « ice-ocean » (marine ice) or « ice-atmosphere » (sea ice) interface. His work is based on numerous field expeditions and laboratory experiments, and on the development of equipments and analytical techniques dedicated to the multi-parametric study of ice: textures and fabrics, stable isotopes of oxygen and hydrogen, total gas content and gas composition, bulk salinity, major elements chemistry…

 

Image of the Week — Looking back at 2016

Image of the Week — Looking back at 2016

Happy New-Yearcorn

I cannot believe that a full year has passed since this very cute pink unicorn wished you a Happy New Year.

Yet, over the past  12 months our blog has attracted more than 16,200 visits.  And the blog analytics show that you, our dear readers, are based not only in Europe but literally all over the world!

With 67 new posts published in only 52 weeks, it’s more than likely that you missed a few interesting ones. Don’t worry, today’s Image Of the Week highlights some of the most exciting content written, edited and published by the whole cryo-team during the year 2016!  

Enjoy and don’t forget to vote in the big EGU Blog competition (see below) !
(Remark
: all the images are linked to their original posts)


Get the most of 2016

Last glaciation in Europe, ~70,000-20,000 years ago [By S. Berger].

The 82 research stations in the Antarctic [By S. Berger].

 

 

 

  • We also launched our new “for dummies” category that aims at explaining complex glaciological concepts in simple terms. The first and most read “for dummies” is all about “Marine Ice sheet instability” and explains why West Antarctica could be destabilised.

Marine Ice Sheet Instability [By D. Docquier].

Three other “for dummies” have been added since then. They unravel the mysteries behind Water Masses, Sea Level and Ice Cores.

  • Drilling an ice core [By the Oldest Ice PhD students]

    Another welcomed novelty of 2016 was the first “ice-hot news” post, about the very exciting quest for the oldest ice in Antarctica. In this post — issued at the same time as the press release —  the 3 PhD students currently involved with the project explain how and where to find their holy grail, i.e. the 1 million year old ice!

The list goes on of course, and I could probably spend hours presenting each of our different posts one by one and explain why every single one of them is terrific. Instead, I have decided to showcase a few more posts with very specific mentions!

 

The oddest place for ice : inside a volcano! [By T. Santagata]

The quirkiest ice phenomenon  : ice balls [By E. Smith].

The most romantic picture : Heart-shaped bubbles for ValentICE’s day [By S. Berger]

The creepiest picture: Blood Falls, Antarctica [By E. Smith]

The funniest post : April Fools “do my ice deceive me” [By S. Berger]

The best incidental synchronisation: The Perito Moreno collapsed the day before our the post went live [By E. Smith]

 

The “do they really do that? ” mention for ballooning the ice [By N. Karlsson]

The best fieldwork fail : Skidoos sinking into the slush [By S. Berger]

The most epic story : Shackleton’s rescue [By E. Smith]

The most puntastic title “A Game of Drones (Part 1: A Debris-Covered Glacier” [By M. Westoby].

The most provocative title : “What an ice hole” [By C. Heuzé]

The soundest post where science is converted to music [By N. Karlsson]

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Good resolutions for 2017

The beginning of a new year is a great opportunity to look back at the previous year, and one of the logical consequences is to come with good resolutions for the coming year.  Thinking of a good resolution and then achieving it can however be tricky.  This is why we have compiled a few resolutions, that YOU dear cryo-followers could easily make 🙂

 Cryoblog stronger in the E(G)U blog competition

To celebrate the excellent display of science writing across all the EGU blogs, a competition has been launched.

Olaf the snowman begs you to vote for “the journey of a snowflake”

From now until Monday 16th January, we invite you, the cryo-readers, to vote for your favourite post of 2016, which should be “journey of a snowflake” (second-to last option). I am obviously being totally objective but if you’re not convinced, the little guy on the right might be more persuasive. If you’re really adventurous, you could also consider clicking on other posts to check what they look like, after having voted for the cryo-one, of course.

Get involved

Hopefully by now:

  1. You are convinced that the cryosphere is amazing and that the EGU cryoblog enables you to seize some of the cryo-awesomeness
  2. You have read and elected the “journey of a snowflake”  as the best post of 2016
  3. You would like to contribute to the blog (because you would like to be part of this great team or simply because you think your sub-field is not represented well enough).

Not to confuse you with a long speech, the image below explains how to get involved. We always welcome contributions from scientists, students and professionals in glaciology, especially when they are at the early stage of their career.

Thank you for following the blog!

PS: this is one of my favourite tweets from the EGU cryospheric division twitter account. What is yours?

Edited by Nanna Karlsson

Image of the Week – The Sound of an Ice Age

Image of the Week – The Sound of an Ice Age

New Year’s Eve is just around the corner and the last “image of the week” of 2016 will get you in the mood for a party. If your celebration needs a soundtrack with a suitably geeky touch then look no further. Here is the music for climate enthusiasts: The sound of the past 60,000 years of climate. Scientist Aslak Grinsted (Centre for Ice and Climate, University of Copenhagen, Denmark) has transformed the δOxygen-18 values from the Greenland NorthGRIP ice core and the Antarctic WAIS ice core into music (you can read more about ice cores in our Ice Cores for Dummies post). Using the Greenlandic data as melody and the Antarctic data as bassline, Aslak has produced some compelling music.

You can listen to his composition and read more about his approach here.

The δOxygen-18 values are a measure of the isotopic composition of the ice, and they are a direct indicator of temperature. The image of the week above shows the isotope values for the past 20,000 years as measured by polar ice cores. On the left-hand side, we are in present-day: an inter-glacial. The δOxygen-18 values are high indicating high temperatures. In contrast, on the right-hand side of the figure we are in the last glacial with lower δOxygen-18 values and lower temperatures. One remarkable thing about these curves is how fast the temperature changes in Greenland (top) compared to Antarctica (bottom). This delayed coupling is called the Bipolar Seesaw.

The clefs are our own addition of course. We have not included the time signature because who knows what the rhythm of the climate might be? (Personally, I think it might be in ¾ like a waltz: An unrestrained movement forward with small underlying variations).

The data from Antarctica is published by WAIS Divide Project Members, 2015. The Greenlandic data can be found on the Centre for Ice and Climate website and in publications by Vinther et al., 2006, Rasmussen et al., 2006, Andersen et al., 2006 and Svensson et al., 2006.

Happy New Year!

 

Image of the Week — Allez Halley!

Image of the Week — Allez Halley!

On the Brunt Ice Shelf, Antarctica, a never-observed-before migration has just begun. As the pale summer sun allows the slow ballet of the supply vessels to restart, men and machines alike must make the most of the short clement season. It is time. At last, the Halley VI research station is on the move!


Halley, sixth of its name

Since 1956, the British Antarctic Survey (BAS) has maintained a research station on the south eastern coast of the Weddell Sea. Named after the 17th century British astronomer Edmond Halley (also the namesake of Halley’s comet), this atmospheric research station is, amongst other things, famous for the measurements that led to the discovery of the ozone hole (Farman et al., 1985).

Due to the inhospitable nature of Antarctica, there have been six successive Halley research stations:

  • Halley I to IV had to be abandoned and replaced when they got buried too deeply beneath the snow that accumulated over their lifetimes (up to ten years per station).
  • Halley V was built on steel platforms that were raised periodically, so the station did not end up buried under snow. However, Halley V was flowing towards the ocean along with the ice shelf when a crack in the ice formed. To avoid finishing up as an iceberg, the station was demolished in 2012.
  • Halley VI, active since 2012, can be raised above the snow and also features skis, so that it can be towed to a safer location if the ice shelf again threatens to crack. However, no one expected that this would have to be put in practice less than 5 years after the station’s opening…

The relocation project, featuring the new October crack. Inset, timeline of the awakening of Chasm 1. The ice shelf flows approximately from right to left. [Credit: British Antarctic Survey].

The awakening of the cracks

The project of moving Halley VI was announced a year ago. A very deep crack in the ice (“Chasm 1” in the map above) upstream of the station and dormant for 35 years, started growing again barely a year after the opening of Halley VI. The risk of losing the station if this part of the ice shelf broke off as an iceberg became obvious, and it was decided to move the station upstream – beyond the crack.

Additionally, there is another problem, or rather another crack, which appeared last October. This one is located north of the station and runs across a route used to resupply Halley VI. This means that of the two locations where a supply ship would normally dock, one is no longer connected to the research station and hence rather useless. Not only is the station now encircled by deep cracks, now it also has only one resupply route remaining; to bring equipment, personnel and food and fuel supplies to the station – all of which are needed to successfully pull off the station relocation.

Bringing Halley VI to its new location before the end of the short Antarctic summer season will be a challenge. We shall certainly keep you up-to-date with Halley news as well as with news about the rapid changes of the Brunt Ice Shelf (because we’re the Cryosphere blog after all!). In the meantime, you can feel like a polar explorer and enjoy this (virtual) visit of Halley VI.

References and further reading

Edited by Clara Burgard, Sophie Berger and Emma Smith

Ice Cores “For Dummies”

Ice Cores “For Dummies”

Ice cores are important tools for investigating past climate as they are effectively a continuous record of snowfall, which preserves historical information about climate conditions and atmospheric gas composition. In this new “For Dummies” post, we discuss the history and importance of ice-core science, and look at the way we can use ice core chemistry to reconstruct past climate.


Ice sheets, archives of our past

When snow falls on the surface of an ice sheet it begins to compact the snow beneath it – eventually it will be compacted enough to be transformed into ice. Simultaneously, atmospheric air held between the snowflakes is slowly trapped in the ice – forming small air bubbles. In areas where mean annual temperatures at the ice surface remain below 0C, such as Greenland and Antarctica, there is little surface melting, so this snow builds up to form thick ice sheets – up to 3000 metres in some part of East Antarctica! Low surface melt means that the snow that is compressed into ice each year forms a continuous record of the annual snowfall and atmospheric gas concentrations at the time of deposition, but how do we access this record..?

Snow that is compressed into ice each year forms a continuous record of the annual snowfall and atmospheric gas concentrations at the time of deposition

…We drill ice cores – of course!

An ice core is a cylinder of ice that is retrieved from the ice sheet by drilling vertically downwards. The core is drilled in sections from the surface, deep into the ice sheet (Fig. 1) using a rotating drill. Each section of the core is processed at the drill site and often cut further into shorter sections of ~55 cm for more practical transport and analysis in labs. A great deal of equipment is needed to achieve this and drilling is a slow and careful process often taking several field seasons to drill a deep core. An example of a drilling camp is shown in Fig. 2, housing scientists and engineers involved in drilling an ice core on the Fletcher Promontory, West Antarctica.

Figure 1: a) Ice core drill being lowered into the ice on Pine Island Glacier [Credit: Alex P. Taylor] b) Dr Rob Mulvaney processing the Berkner Island ice core, Weddell Sea, Antarctica [Credit: R. Mulvaney]

Figure 2: The layout of the Fletcher Promontory ice-drilling project, Weddell Sea, Antarctica. In the background the large Weatherhaven tent houses the drill rig, the central Weatherhaven tent is used for storage and equipment and a simple shower, the nearest Polarhaven tent is the mess tent, and the Polarhaven tent to the left houses the main generator. The pyramid tents in the foreground are the sleeping tents, and the two to the right are used for toilet facilities [Credit: Mulvaney et al., 2014]

Where to drill an ice core for the best record?

To get a good record of climate we want to find an area of ice that has many annual layers (good temporal resolution) that has not been disturbed by high ice flow velocities, usually these conditions can be found at an ice dome or divide. An ice sheet is a large plateau with a relatively stable rate of annual snowfall; the dome (or ice divide) is the point in the ice sheet where there is only vertical flow (compression) of ice (Fig. 3). Horizontal flow of ice is greater with the greater distance from the dome. Therefore, domes are the ideal site on the ice sheet or ice cap to drill for an ice core to ensure no interference with the snowfall history at the site. It is reasonable to assume that the ice-core record taken from a site with high annual snowfall will not extend the furthest back in time; similarly, a low annual snowfall and a large ice-sheet thickness will offer a record spanning much further back in time.

Figure 3: Ice flow within the ice sheet showing the zero flow at the ice divide – the ideal site for an ice core [Credit: Snowball Earth]

For Antarctica, the amount of snowfall across the ice sheet depends on the distance from the coast and sources of moisture; the highest mean annual snowfall is found at West Antarctic ice sheet sites whilst the lowest values are inland on the East Antarctic ice sheet, one of the driest deserts on Earth. In addition to the West and East Antarctic ice sheets, the Antarctic Peninsula is the third and final sector of the continent with high mean annual snowfall comparable to West Antarctica. In comparison to Antarctica, the Greenland ice sheet has a relatively high present-day mean annual snowfall, varying across the ice sheet between 10 and 30 cm per year. Therefore, if your aim is to find the oldest ice on Earth, East Antarctica is a good place to start looking, see our post on the quest to drill an ice core that contains ice which is over a million years old. Additionally, for the longest records it is paramount to find a drilling location with no (or at least very low) annual melting at the bedrock.

If your aim is to find the oldest ice on Earth, East Antarctica is a good place to start looking

What does an ice core actually record?

Once an ice core has been drilled and cut into sections, some of the sections are analysed and others are preserved. This is particularly important as some of the analysis is destructive (e.g. melting of the ice to extract water and gas). Therefore an archive of the ice core itself is needed. So, what information can we obtain from analysing the core and how is it done?

Annual layers, past snowfall and past temperatures!

Reconstructing the past surface temperature and snowfall is incredibly useful for understanding climate processes and changes through time in order to assess any present-day local and regional changes in climate. We can do this by:

          • Measuring the thickness of the annual layers: This is done by counting layers in the core, either by visual identification of the peaks in deposition or use of a computer algorithm. The thickness of a specific year depends on how much snow fell at the site and on how much the snowfalls of the following years compacted this specific layer. We can estimate the strain caused by compaction which allows us to extract historical annual snowfall.
          • Past air temperatures (Stable Water Isotope Record): An additional method to reconstruct past snowfall is from the ratios of the stable water isotopes from the water that forms snow and precipitation. The ratio of stable water isotopes has a linear relationship with surface temperature (see box below). Mathematical reconstructions of accumulation using the temperature reconstructions from stable water isotopes are employed in ice core profiles where the compaction of annual snowfall results in an annual layer thickness beyond standard laboratory resolution, such as Antarctic sites. Following the accumulation reconstruction, the rate of compaction of the annual snowfall to ice and subsequent ‘thinning’ of the deposited snowfall layer must be estimated by glaciological modelling.
          • Trace-element analysis: For the upper depths of a deep ice core, or an ice core with an easily-resolvable annual layer thickness, the continuous analysis of an ice core for stable water isotopes offers a sub-annual view of the climate record.

            Figure 4: Seasonal deposition of four chemical species in the WAIS Divide ice core. Pink: electrical conductivity measurements; Black: Black Carbon; Red: non-sea salt Sulphur; Blue: Sodium. Each panel, shows the averaged annual record for 2 different periods: the Antarctic Cold Reversal (ACR, 13-14,000 years ago – bold line) and the Holocene, (10-11,000 years ago – thin line) the [Credit: Fig. 2, Sigl et al., 2016 ]

            The deposition of a number of chemical elements increases during the summer season and decreases during the winter.When these elements are measured in the ice core they can be depicted as an almost-sinusoidal record, indicating the historical seasons. High-resolution ice-core profiles can be dated by counting these annual layers, and have been done so across Greenland and at the West Antarctic Ice Sheet (WAIS) Divide ice core site. Fig. 4 shows two annual signals over 24 months for four different chemicals that are deposited in ice cores (Sigl et al., 2016). The peak in seasonal deposition is shown twice for each chemical, at different times in history, but the seasonality of these species remains strong throughout time.
Reconstructing Past Temperatures
We commonly think of water as H2O - a molecule containing two hydrogen atoms and one oxygen atom. However, atoms (i.e. Hydrogen and Oxygen) come in several forms, known as isotopes - atoms with the same number of protons, but differing numbers of neutrons. Those isotopes that don't decay over time and are preserved in the ice core are know as stable water isotopes. It is possible to measure the amount of each different stable water isotope present in an ice core by melting the ice core and using a mass spectrometer to analyse the water produced.

The snow that eventually forms ice cores starts its life as ocean water which is evaporated and transported to the polar regions. Water isotopes with more neutrons are heavier and therefore require more energy to evaporate and transport. The amount of energy available to do this is related to temperature. Therefore heavier isotopes are found in ice cores in higher amounts at warmer periods in the planet's history! Find out more  here!

Atmospheric gas

Ice-core measurements of atmospheric gases correlate well with direct measurements taken from the atmosphere dating back to 1950. As a result of this, ice-core scientists can assume that the atmospheric gas concentrations measured in ice cores reflects the atmospheric conditions at the time the gas was entrapped in the ice core. Hence, ice cores tell us that carbon dioxide concentrations have been relatively stable for the last millennia until around 1800 AD but since then a rise of almost 40% has been measured in both ice cores and direct atmospheric measurements (Fig. 5).

Figure 5: 1000 years of atmospheric CO2 concentrations from various Antarctic ice cores (DML, South Pole, Law Dome and Siple Dome) and the direct measurements in Mauna Loa Observatory [Credit: Ashleigh Massam, compiled from open access data sources]

Carbon dioxide concentrations have been relatively stable for the last millennia until around 1800 AD but since then a rise of almost 40% has been measured

In addition to comparison with present-day measurements, the trapped gases offer a record of direct atmospheric and greenhouse gas concentrations, including methane, carbon dioxide and nitrous oxide (Fig. 6) on a longer timescale – up to 800,000 years (Loulergue et al., 2008). Records show the connection between fluctuations in the atmosphere and long-term global climate variations (e.g. temperature) on a millennial timescale (Kawamura et al., 2007). The long-term trends show a pattern in the gas concentrations that compare well with glacial-interglacial climate. The phasing and timing of the eight glacial cycles covered by this record are dominated by the orbital cycle of the Earth on a 96,000-year periodicity, with a warm, interglacial period between each cold period. However, as we will see later in this blog post, this may not be the case when we look further back in time!

Figure 6: Variations of temperature (from present day mean temperature, black), atmospheric carbon dioxide (in part per million by volume — blue) and methane (in part per billion per volume red) over the past 800,000 years, from the EPICA Dome C ice core in Antarctica. Modern value (of 2009) of carbon dioxide and methane are indicated by arrows. [Credit : Centre for Ice and Climate , University of Copenhagen. Re-used with permission ]

Other climate proxies

Chemistry preserved in the ice also offers a proxy (=a means) to reconstruct other seasonally-deposited tracers:

                        • Information on past sea-ice extent can be obtained from chemicals found in ice cores which are also present in sea salt such as sodium, chlorine and methanesulphonic acid (MSA) (Sommer et al., 2000; Curran et al., 2003; Rothlisberger et al., 2003).
                        • The seasonal deposition of elements such as iron, magnesium and calcium, which are linked to dust from far-afield and the short-term climate variability such as atmospheric circulation (Fuhrer et al., 1999).
                        • Finally, volcanic layers in the ice core such as tephra and sulphate deposit provides a unique timestamp to a specific depth. These layers were deposited at the same time, all over the world and can be pinpointed to a specific volcanic eruption. Deposits of the same layer outside of a glaciated landscape, (e.g. within rock layers ) can often be dated using radiocarbon (Carbon-14) or another radiogenic dating methods. Additional age horizons can be interpreted by events assumed to occur in the world at the same time, such as rapid climate events. Age constraints are beneficial to interpreting deep ice-core records that are not analysed at a sub-annual resolution by offering pinpoint age horizons to an ice-core record.

Current knowledge from ice-core records

As we have seen, ice core are important because they put the current climate variations into the context of a long-term climate history. Additionally, polar ice cores can allow us to looks at variations between the northern and southern hemisphere. Ice cores also extend back much, much further in time than terrestrial weather stations or satellite records:

Figure 7: Deep ice core locations in Greenland and Antarctica [Credit and more details: NSIDC ]

The current past climate record tells us about glacial and inter-glacial periods (Fig. 6) but also allows us to look at finer detail – i.e. the variability within these periods, which were previously assumed stable.  For example, ice cores have led to the discovery of Dansgaard-Oeschger events; which are are rapid climate fluctuation events, characterised by rapid warming followed by gradual cooling to return to glacial conditions, 25 of these events have happened during the last glacial period.

Records from the Northern and Southern hemisphere also allow us to link these small and large scale changes in climate in the two hemispheres. For example, ice cores analysed from both poles show a ‘call and response’ signal between Dansgaard-Oeschger events in the Northern Hemisphere and events in the Antarctic climate record. The southern hemisphere cooled during the warm phases of Dansgaard-Oeschger events in the northern hemisphere (Buizert et al., 2015), and vice versa during northern hemispheric cooling (see our previous blog post on the subject).

There are already over a dozen ice cores taken from Greenland and Antarctica (Fig. 7), offering a clear and detailed history of the climate during the Late Quaternary period (Fig. 6), going back up to 800,000 years (Quaternary = last 2.6 million years). As we mentioned earlier the timing of glacial and inter-galcial cycles in this 800,000 year old record is dominated by the orbital cycle of the Earth (96,000-year periodicity). However, marine records show that frequency of glacial-interglacial cycles was different before this time (Lisiecki and Raymo, 2005). It is in order to better understand these changes that the quest for the oldest was formed – beginning last month the mission aims to drill an ice core of ice older than 800,000 years to gain detailed information about the climate even further back in time.

Detailed records from high-resolution ice cores improves our understanding of the response of the planet to deglaciation events

The continuous and high-resolution of ice-core records, together with marine and terrestrial records, offers a global view of coupled processes from ice sheet calving events, changes to ocean circulation and heat transport and the subsequent cooling events across the Earth. Detailed records from high-resolution ice cores improves our understanding of the response of the planet to deglaciation events from the large ice sheets that once covered much of the northern hemisphere. Melting ice sheets pose a significant threat to the planet from rising sea levels and the freshwater input leading to inevitable changes in climate.

Edited by Emma Smith and Sophie Berger


Ashleigh Massam is a final-year PhD student based in the Ice Dynamics and Palaeoclimate group at the British Antarctic Survey and with the Department of Geography at Durham University. Her project is developing the age-depth profiles of three ice cores drilled at James Ross Island, Fletcher Promontory and Berkner Island, West Antarctica, by a combination of high-resolution trace-element analytical techniques and modelling ice-sheet processes.

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