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Cryospheric Sciences

Image of the Week

Image of the Week – Icelandic glaciers monitored from space!

Image of the Week – Icelandic glaciers monitored from space!

Located in the North Atlantic Ocean, just south of the polar circle, Iceland is a highly fascinating land. Covered by some of the largest glaciers in Europe and hosting active volcanoes, geothermal sites and subglacial lakes, it is extremely dynamic in nature and ever changing. With this Image of the Week we will tell you a bit about the changing ice caps of Iceland and how we can monitor them from space!


Icelandic ice caps since the mid-1990s

Iceland enjoys a mild and moist climate because of the relatively warm and saline Irminger current transporting heat to its southern coast, although the cold East Greenland and East Icelandic currents may cause sea ice to form to the north. Iceland’s ice caps, which receive abundant precipitation from North Atlantic cyclones, cover about 11% of the land, and contain ~3600 km2 of ice. If they completely melted they would contribute 1 cm to Sea Level Rise (SLR).

In the period 1995-2010, Icelandic glaciers shrank every year and lost mass at an average rate of 9.5±1.5 Gton a-1 – generally reflecting higher summer temperatures and longer melting seasons than in the early 1990s (Björnsson et al., 2013). Importantly, in recent decades Iceland has been the second largest source of glacier meltwater to the North Atlantic after Greenland and its peripheral glaciers. Furthermore, surge-type outlet glaciers – which have unpredictable dynamics – are present in all Icelandic ice caps and represent as much as 75% of the area of Vatnajökull (Bjornsson et al., 2003), the largest ice cap in Europe by volume. Therefore, it is important to continuously monitor Icelandic ice caps (>90% of the whole glaciated area) at high spatial resolution. Glaciological field surveys can yield accurate measurements and are routinely performed in Iceland on all ice caps and most glaciers. However, it is not always feasible to use field methods, depending on the remoteness and size of the glacier (e.g. several glaciers and ice caps in the Arctic). Continuous monitoring of such hardly accessible areas can be achieved from space at high spatial resolution.

Continuous health check from space

Since 2010, the ESA CryoSat-2 (CS2) mission has been fundamental in retrieving ice elevation data over glacial terrain characterised by complex topography and steep slopes – notoriously hard to monitor via satellite. CS2’s radar altimeter provides the elevation of the Point-Of-Closest-Approach (POCA) – the point at the surface closest to the satellite on a straight line – every ~400 m along the flight track. The main novelty of this mission is the use of a second antenna, which allows the use of interferometry across-track to accurately infer the location of a surface reflection in presence of a slope (read more about it here). Additionally, a new and exciting application of CS2 interferometric capabilities is that we can exploit the echos after the POCA, i.e. the reflections coming from the sloping surface moments after the first one. This approach generates a swath of elevations every ~400 m and provides up to two orders of magnitude more elevation data than with conventional POCA processing (Fig. 2; Gray et al., 2013, Foresta et al., 2016).

Since 2010, the ESA CryoSat-2 (CS2) mission has been fundamental in retrieving ice elevation data

Figure 2: Example of the improved elevation data using CS2 swath-processing. CS2 swath data (colors) and conventional (circles) heights over the Austfonna ice cap (Svalbard) for two satellite passes. Swath processing delivers up to two orders of magnitude more elevation data. [Credit: Dr. N. Gourmelen,University of Edinburgh, School of GeoSciences]

This rich dataset can be used to generate maps of surface elevation change rates at sub-kilometer resolution (Figs. 1 and 3). These maps show extensive thinning of up to -10 m a-1 in marginal areas of Iceland’s ice caps, while patterns of change are more variable in their interior. Fig. 3 shows the difference in spatial coverage between the POCA and Swath approaches, with the former sampling preferentially along topographic highs (see for example the Langjökull ice cap in Fig. 3). Using these high resolution maps, it is possible to independently infer the mass balance of each ice cap purely from satellite altimetry data. Based on CS2 swath-processed elevations, between glaciological years 2010/11 and 2014/15 Iceland has lost mass at an average rate of 5.8±0.7 Gton a-1 contributing 0.016±0.002 mm a-1 to SLR (Foresta et al., 2016). The rate of mass loss is ~40% less than during the preceding 15 years, partly caused by Vatnajökull (63% of the total mass loss) having had positive mass balance during the glaciological year 2014/15 due to anomalously high precipitation. Langjökull, with widespread thinning up to the ice divide (Figs. 1 and 3), is the fastest changing ice cap in terms of mass loss per unit area.

between glaciological years 2010/11 and 2014/15 Iceland has lost mass at an average rate of 5.8±0.7 Gton a-1 contributing 0.016±0.002 mm a-1 to SLR

Beside estimating mass change at the ice cap scale, the novel swath approach demonstrates the capability to observe glaciological processes at a sub-catchment scale. Different accumulation and thinning patterns over Vatnajökull and Langjökull, for example, are directly related to past surges or subglacial volcanic eruptions, some of which happened decades ago. Their long term lingering effects on the ice cap topography are now visible from space and as the satellite data record extends we will be able to gain an increased understanding of how these effects evolve over time.

Figure 3 – Comparison between swath-processed (Swath) and conventional (POCA) surface elevation change rates over the six largest ice caps in Iceland, representing 90% of the glaciated area. V (Vatnajökull), L (Langjökull),H(Hofsjökull),M(Mýrdalsjökull), D (Drangajökull), and E (Eyjafjallajökull). The inset shows the location of individual elevation measurements by using Swath and POCA approaches over Langjökull. [Credit: After Foresta et al. (2016).]

Edited by Emma Smith


Luca Foresta is a PhD student in the Glaciology and Cryosphere Research Group at the University of Edinburgh (@EdinGlaciology), and his research focuses on improving CryoSat-2 processing as well as exploiting swath-processed CryoSat-2 data to quantify surface, volume and mass changes over ice caps.

 

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 – Supraglacial debris variations in space and time!

Image of the Week – Supraglacial debris variations in space and time!

There is still a huge amount we don’t know about how glaciers respond to climate change. One of the most challenging areas is determining the response of debris-covered glaciers. Previously, we have reported on a number of fieldwork expeditions to debris-covered glaciers but with this Image of The Week we want to show you another way to investigate these complex glaciers – numerical modelling!


Debris-covered glaciers

Debris-covered glaciers occur globally, with a great many being found in the Himalaya-Karakoram mountain range. For example, in the Everest Region of Nepal 33% of glacier area is debris covered (Thakuri et al., 2014). The response of debris-covered glaciers to future climate change in such regions has huge implications for water resources, with one fifth of the world’s population relying on water from the Himalayan region for their survival (Immerzeel et al., 2010).

Debris-covered glaciers respond to climate change differently to debris-free glaciers as the supraglacial debris layer acts as a barrier between the atmosphere and glacier (Reznichenko et al., 2010). The supraglacial debris layer has several key influences on the glacier dynamics:

  • Glacier ablation (loss of mass from the ice surface) is enhanced or inhibited depending on debris layer thickness and properties – see our previous post.
  • Supraglacial debris causes glaciers to reduce in volume through surface lowering rather than terminus retreat (typical of debris free mountain glaciers).

Understanding the influence of a supraglacial debris layer on mass loss or gain is, therefore, key in determining the future of these glaciers. The properties of supraglacial debris layers can vary in time and space both in debris layer thickness and distribution, as well as properties of the rocks which make up the debris (e.g. albedo, surface roughness, porosity, size and moisture content). It is these characteristics of the debris-cover which control the heat transfer through the debris and therefore the amount of thermal energy that reaches the underlying ice causing melting (Nicholson and Benn, 2006). In order to better predict the future of debris-covered glaciers we needs to be able to numerically model their behaviour. This means we need a better understanding of the variations in debris cover and how this affects the ice dynamics.

How does a supraglacial debris layer vary in time and space?

Our Image of the Week (Fig. 1) shows a schematic of how debris distribution can vary spatially across a glacier surface and also this can change through time. The main inputs of debris are:

  • Upper regions: snow and ice avalanches in the upper reaches of the glacier.
  • Mid and Lower regions: rock avalanches and rock falls (Mihalcea et al., 2006).

These irregular mass movement events vary in frequency and magnitude, and therefore affect debris distribution across the glacier surface but also through time. The irregularity of them makes it really hard to predict and simulate! Luckily, debris transport is a little more predictable.

Figure 2: An ice cliff emerging out of the supraglacial debris layer on Khumbu Glacier, Nepal, with Nuptse in the background. [Credit: M. Gibson]

Debris is initially transported along medial moraines (glacially transported debris)  in the upper and mid-sections of the glacier, this is known as entrained debris. The various sources of entrained debris combine to form a continuous debris cover in the lower reaches of the glacier (Fig. 1). As a supraglacial debris layer is forming, such as for Baltoro glacier (Fig. 1), the boundary between the continuous debris layer and entrained debris sections progresses further upglacier over time.

Eventually transported debris will reach the terminus of the glacier and be deposited (Fig. 1), mainly due to a decrease in surface velocity of the glacier towards the terminus. However, once debris is deposited it doesn’t just sit there; debris is constantly being shifted around as ablation (surface melting) occurs. As ablation occurs the debris surface ablates unevenly, as the thickness of the debris layer is spatially variable. Uneven ablation, otherwise known as differential surface lowering, causes the glacier surface to be made up of topographic highs and lows, the latter of which sometimes become filled with water, forming supraglacial ponds (Fig. 1) . Another product of debris shifting is that ice cliffs, such as the one seen in Fig. 2, are exposed. These features are initially formed when englacial channels collapse  or debris layers slide (Kirkbride, 1993). All this movement and shifting means that not only do glacier models have to consider variation in debris layers across the glacier and through time, but also the presence of ice cliffs and supraglacial ponds. They are important as they have a very different surface energy balance to debris-covered ice. To complicate things further the frequency and area of ice cliffs and supraglacial ponds also vary through time! You see the complexity of the problem…

Modelling spatially and temporally varying debris layers

Numerical modelling is key to understanding how supraglacial debris layers affect glacier mass balance. However, current numerical modelling often either omits the presence of a supraglacial debris layer entirely, or a debris layer that is static in time and/or space (e.g. Collier et al., 2013; Rowan et al., 2015; Shea et al., 2014). However, as outlined earlier, these supraglacial debris layers are not static in time or space. Understanding the extent to which spatiotemporal variations in supraglacial debris distribution occur could aid identification of when glaciers became debris-covered, glaciers that will become debris-covered glaciers in the future, and the timescales over which supraglacial debris layers vary. The latter is particularly relevant to numerical modelling as it would result in total glacier ablation being calculated more precisely throughout the modelling time period. Understanding the interaction between glacier dynamics and debris distribution is therefore key to reconstructing debris-covered glacier systems as accurately as possible.

Edited by Emma Smith


Morgan Gibson is a PhD student at Aberystwyth University, UK, and is researching the role of supraglacial debris in ablation of Himalaya-Karakoram debris-covered glaciers. Morgan’s work focuses on: the extent to which supraglacial debris properties vary spatially; how glacier dynamics control supraglacial debris distribution; and the importance of spatial and temporal variations in debris properties on ablation of Himalaya-Karakoram debris-covered glaciers. Morgan tweets at @morgan_gibson, contact email address: mog2@aber.ac.uk.

Image of the Week – On the tip of Petermann’s (ice) tongue

Image of the Week – On the tip of Petermann’s (ice) tongue

5th August 2015, 10:30 in the morning. The meeting had to be interrupted to take this picture. We were aboard the Swedish icebreaker Oden, and were now closer than anyone before to the terminus of Petermann Glacier in northwestern Greenland. But we had not travelled that far just for pictures…


Petermann’s ice tongue

Petermann is one of Greenland’s largest “marine terminating glaciers”. As the name indicates, this is a glacier, i.e. frozen freshwater, and its terminus floats on the ocean’s surface. Since Petermann is confined within a fjord, the glacier is long and narrow and can be referred to as an “ice tongue”.

Petermann Glacier is famous for its recent calving events. In August 2010, about a quarter of the ice tongue (260 km2) broke off as an iceberg (Fig. 2). In July 2012, Petermann calved again and its ice tongue lost an extra 130 km2.

These are not isolated events. Greenland’s marine terminating glaciers are all thinning and retreating in response to a warming of both air and ocean temperatures (Straneo et al., 2013), and Greenland’s entire ice sheet itself is threatened. Hence, international fieldwork expeditions are needed to understand the dynamics of these glaciers.

Fig. 2: The 2010 calving event of Petermann. Natural-color image from the Advanced Land Imager (ALI) on NASA’s Earth Observing-1 (EO-1) satellite ( August 16, 2010).  [Credit: NASA’s Earth Observatory]

The Petermann 2015 expedition

In summer 2015, a paleoceanography expedition was conducted to study Petermann Fjord and its surroundings, in order to assess how unusual these recent calving events are compared to the glacier’s past. Our small team focused on the present-day ocean, and specifically investigated how much of the glacier is melted from below by the comparatively warm ocean (that process has been described on this blog previously). In fact, this “basal melting” could be responsible for up to 80% of the mass loss of Petermann Glacier (Rignot, 1996). Additionally, we were also the first scientists to take measurements in this region since the calving events.

Our results are now published (Heuzé et al., 2017). We show that the meltwater can be detected and tracked by simply using the temperature and salinity measurements that are routinely taken during expeditions (that, also, has been described on this blog previously). Moreover, we found that the processes happening near the glacier are more complex than we expected and require measurements at a higher temporal resolution, daily to hourly and over several months, than the traditional summer single profiles. Luckily, this is why we deployed new sensors there! And since these have already sent their data, we should report on them soon!

Edited by David Rounce and Sophie Berger

References and further reading

Image of the Week – For each tonne of CO2 emitted, Arctic sea ice shrinks by 3m² in summer

Image of the Week – For each tonne of CO2 emitted, Arctic sea ice shrinks by 3m² in summer

Declining sea ice in the Arctic is definitely one of the most iconic consequences of climate change. In a study recently published in Science, Dirk Notz and Julienne Stroeve find a linear relationship between carbon dioxide (CO2) emissions and loss of Arctic sea-ice area in summer. Our image of this week is based on these results and shows the area of September Arctic sea ice lost per inhabitant due to CO2 emissions in 2013.


What did we know about the Arctic sea ice before this study?

Since the late 1970s, sea ice has been dramatically shrinking in the Arctic, losing 3.8% of its area per decade. Sea-ice area is at its minimum in September, at the end of the melting season.

The main cause of this loss is the increase in surface temperature over the recent years (Mahlstein and Knutti, 2012), which has been more pronounced in the Arctic compared to other regions on Earth (Cohen et al., 2014). The use of statistical methods involving both observations and climate models shows that the recent warming in the Arctic can be attributed to human activity, i.e. mainly greenhouse gas emissions (Gillett et al., 2008). This suggests a direct link between human activity and Arctic sea-ice loss, which is confirmed in the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC).

How exactly is sea-ice loss related to CO2 emissions ?

Notz and Stroeve (2016) relate the Arctic sea-ice decline to cumulative CO2 emissions since 1850 (i.e. the total amount of CO2 that has been emitted since 1850) for both observations and climate models. Cumulative CO2 emissions constitute a robust indicator of the recent man-made global warming (IPCC, 2014).

The two quantities are clearly linearly related (see Figure 2). From 1953 to 2015, about 3.5 million km² of Arctic sea ice have been lost in September while 1200 gigatonnes (1 Gt = 10e9 tonnes) of CO2 have been emitted to the atmosphere. This means that for each tonne of CO2 released into the atmosphere, the Arctic loses 3 m² of sea ice.

Fig 2: Monthly mean September Arctic sea-ice area against cumulative CO2 emissions since 1850 for the period 1953-2015. Grey circles and diamonds show the results from in-situ (1953-1978) and satellite (1979-2015) observations, respectively. The thick red line shows the 30-year running mean and the dotted red line represents the trend of 3 m² sea-ice area loss per tonne of CO2 emitted. [Credit: D. Notz, National Snow and Ice Data Center ]

Starting from the relationship between cumulative CO2 emissions and sea-ice area, it is then easy to attribute to each country in the world their own contribution to sea-ice loss based on their CO2 emissions per capita. The countries that stand out in the map are thus the countries emitting the most in relation to their population.

Could the Arctic be ice-free in the future?

If this relationship holds in the future (in other words, if we extend the red dotted line to zero sea-ice area in Figure 2), adding 1000 Gt of CO2 in the atmosphere would free the Arctic of sea ice in September. Since we are currently emitting about 35 Gt CO2 per year, it would take less than 30 years to have the Arctic free of sea ice in the summer (which confirms previous model studies (e.g. Massonnet et al., 2012)).

Edited by Clara Burgard and Sophie Berger

Further reading

DavidDavid Docquier is a post-doctoral researcher at the Earth and Life Institute of Université catholique de Louvain (UCL) in Belgium. He works on the development of processed-based sea-ice metrics in order to improve the evaluation of global climate models (GCMs). His study is embedded within the EU Horizon 2020 PRIMAVERA project, which aims at developing a new generation of high-resolution GCMs to better represent the climate.

Image of the Week – It’s all a bit erratic in Yosemite!

Image of the Week – It’s all a bit erratic in Yosemite!

When you think of California, with its sun-soaked beaches and Hollywood glamour, glaciers may not be the first thing that spring to mind – even for ice nerds like us. However, Yosemite National Park in California’s Sierra Nevada is famous for its dramatic landscape, which was created by glacial action. With our latest image of the week we show you some of the features that were left behind by ancient glaciers.


What do we see here?

Although Yosemite is now largely glacier-free the imprint of large-scale glaciation is evident everywhere you look. During the last glacial maximum (LGM), around 26,000 to 18,000 years ago, much of North America was covered in ice. Evidence of this can be seen in the strange landscape, shown in our image of the week. The bedrock surface in this area is polished and smoothed due to a huge ice mass that was moving over it, crushing anything in it’s path. When this ice mass melted rocks and stones it transported were released from the ice and left strewn on the smoothed bedrock surface. These abandoned rocks and stones are know as glacial erratics. Some of these erratics will have travelled from far-away regions to their resting place today.

During the last glacial maximum (LGM), around 26,000 to 18,000 years ago, much of North America was covered in ice.

Glaciers that still remain!

There are still two glaciers in Yosemite, Lyell and Maclure, residing in the highest peaks of the National Park. Park rangers have been monitoring them since the 1930s (Fig. 2), so there is a comprehensive record of how they have changed over this period. Sadly, as with many other glaciers around the world this means a huge amount mass has been lost – read more about it here!

Figure 2: Survey on Maclure Glacier by park rangers in the 1930s [Credit: National Parks Service]

On a more cheerful note – Here at the EGU Cryosphere Blog we think it is rather fantastic that the park rangers of the 1930s conducted fieldwork in a suit, tie and wide-brimmed hat and we are hoping some of you might be encouraged to bring this fashion back! 😀

If you do please make sure to let us know, posting it on social media an tagging us @EGU_CR! Here are a few more ideas of historical “fieldwork fashion” to wet your appetite: Danish explorers in polar bear suits, 1864-65 Belgian-Dutch Antarctic Expedition and of course Shackleton’s Endurance expedition!


Imaggeo, what is it?

You like this image of the week? Good news, you are free to re-use it in your presentation and publication because it comes from Imaggeo, the EGU open access image repository.

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 – Let it snow, let it snow, let it snow…

Image of the Week – Let it snow, let it snow, let it snow…

Christmas is coming to town and in the Northern Hemisphere many of us are still dreaming of a white Christmas, “just like the ones we used to know”. But how likely is it that our dreams will come true?


What is the definition of a White Christmas ?

Usually Christmas can be defined as a “White Christmas” if the ground is covered by snow on either Christmas Eve or Christmas Day depending on local traditions. If you believe Christmas movies, it seems like Christmas was accompanied by snow much more often in the past than today! But is this really the case, or is it just the “Hollywood” version of Christmas? According to the UK Met Office White Christmases were more likely in the past. Due to climate change, average global temperatures are higher, which in many places reduces the chance of a White Christmas. However, the chances of a White Christmas also depend strongly on where you live…

Living in Western or Southern Europe, the Southern US or the Pacific coast of the US? Unlucky you!

Not too surprisingly, most of the inhabitants of Portugal, Southern Spain, and Southern Italy have probably never experienced White Christmas in their hometown. Maybe more counter intuitively the probability of a White Christmas is also low in most of France, the Netherlands, Ireland, and the Southern UK! In the US, the probability of a White Christmas increases from South to North, except on the Pacific Coast, which has a very low probability of a White Christmas.

Probability of a White Christmas in Europe (snow on the ground on 25th of December), inferred from reanalysis data (ERA Interim from 1979-2015). Probability [in %] increases from white to blue [Credit : Clara Burgard, Maciej Miernecki. We thank the ECMWF for making the data available]

What influences the probability of snowfall on Christmas?

The mean air temperature decreases with altitude and latitude, meaning that chances of a white Christmas increase the further North and at the higher you travel. However, coastal regions represent an exception. The air often has traveled over the ocean before reaching land. As the ocean is often warmer than the land surface in winter, the air in coastal regions is often too warm for snow to form. Additionally, in the Northern Hemisphere, ocean currents on the Western coast of the continents tend to carry warm water to high latitudes, while ocean currents on the Eastern coast tend to carry cold water to low latitudes. The probability of snowfall is therefore even lower in Western coastal regions (e.g. Pacific coast of the US, Atlantic coast of Europe).

Don’t despair !

If you want to increase your chances of experiencing a White Christmas, you have three solutions:

    1. You already live in an area with high probability of White Christmas (lucky you!) – Sit tight and do a “snow dance”, here is one suggestion that we have heard works well:

    2. Travel or move to one of these 10 suggested destinations (e.g. St. Moritz, Swizerland)

      Frozen Lake St. Moritz in Winter 2013 [Credit: Wikimedia Commons]

    3. Build your own snow with this simple recipe!

We hope that you find a satisfactory solution that makes you happy this Christmas. Otherwise, remember that snow is not the only thing that defines Christmas. Enjoy the relaxed time with family and friends and prepare yourself for the coming new year! If you find yourself at a loose end, then there is always the back catalogue of EGU Cryosphere Blog posts to read – and we guarantee a healthy dose of snow and ice can be found here.

So, this is it from the EGU Cryosphere blog team for 2016. See you in 2017 – after all, the snow must go on…

Further reading:

      •  MetOffice website with interesting facts around White Christmas!

Edited by Emma Smith

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

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