CR
Cryospheric Sciences

Image of the Week

Image of the Week – The solid Earth: softer than you might think!

Rebounding beach in the Canadian Artic [Credit : Mike Beauregard distributed by Wikimedia Commons]

Global sea level is rising and will continue to do so over the next century, as has once again been shown in the recent IPCC special report on 1.5°C. But did you know that, in some places of our planet, local sea level is actually falling, and this due to rising of the continent itself?! Where is this happening? In places where huge ice sheets used to cover the land surface during the last ice age, such as Scandinavia, Canada, or Siberia. Even though these ice sheets melted several thousands of years ago, the land that once lied under them is still rising in reaction to the release of their previous burden. This is what we call Glacial Isostatic Adjustment or GIA. Where does this adjustment come from? Our Earth is not as solid as you would think…


Our Image of the Week represents a layered beach located in Nunavut, in the Canadian Arctic. This specific landform is caused by the glacial rebound of the Arctic coastline resulting from the response of the lithosphere to the melting of the Laurentide Ice sheet, an ice sheet that used to cover the North American continent until less than 10 000 years ago.

Earth during Last Ice Age [Credit: Wikimedia Commons]

What is Glacial Isostatic Adjustment?

Imagine sitting on a very comfy couch, watching a movie. At the end of the movie, the couch has perfectly adapted to the shape of your body. Once you get up, you’re still able to see where you’ve been sitting, as the couch takes a little time to get back to its original form. Well… this is exactly what happens with the Earth’s crust and mantle. To understand this, you need to visualize the internal structure of our planet Earth, which is layered in spherical shells: under our feet lie the rocky tectonic plates, which constitute the Earth’s crust. These crusty plates – whose thickness varies between a few kilometers under oceans to a few tens of kilometers under the continents – are floating on a viscous layer, called the mantle. It is almost 3000 kilometers thick and actually slowly flows like a liquid, at a speed of a few centimeters per year.

Even though the Earth’s crust is a very strong material, the pressure applied by an ice sheet thick of several kilometers is so important that the crust will locally deform under the heavy ice mass, sinking down into the viscous mantle. That’s what happened over large areas of the Northern Hemisphere that were covered by ice masses during the last ice age, and what is still happening in the remaining ice sheets of Greenland and Antarctica, which have been depressing the Earth’s crust beneath them for thousands of years.

Just like for the couch in the example above, when the weight is removed, the mantle rebounds, carrying with it the overlying crust. Over the 20 000 years since the last glacial maximum, lands now relieved of their previous ice-burden are gradually rebounding. The Earth’s delayed response to the variation of mass on its surface is explained by the viscous character of the Earth’s mantle.

Glacial Isostatic Adjustment [Credit: Wikimedia Commons]

Why is it important to take it into account?

Even though the Siberian, Scandinavian and Laurentide ice sheets melted several thousands of years ago (causing a rise in global sea level), these regions that were previously glaciated are still locally emerging to compensate the loss of their overlying weight. The level of the coastline relative to the local sea-level thus increases. One says that the “relative sea level” is falling, and this at a rate that is essentially determined by the rate of the post-glacial rebound (which can exceed 1 cm/year in some areas, as shown in the figure below!). The rates of relative sea level can be influenced even at sites that are quite far away from the centres of the last glaciation, although it is much less significant.

Rate of the post-glacial rebound [Credit: NASA, Wikimedia Commons]

A good understanding of glacial isostatic adjustment is important to distinguish the different components and contributors to a local sea-level evolution: what part is due to the uplift of the land? And what part is due to the rising of global sea-level?
In addition, glacial isostatic adjustment also impacts the behaviour of  modern Greenland and Antarctic ice sheets. By influencing the geometry of the underlying bedrock, it will impact the sensitivity of the ice sheet to global warming and thus the glacial isostatic adjustment itself: this is a vicious circle!

The problem is that glacial isostatic adjustment also depends on the local properties of the Earth’s crust and mantle, which are not constant at the Earth’s surface. A lot of work is still needed to understand all of this properly. Luckily, since NASA launched GRACE – a satellite mission that maps variations in the Earth’s gravity field –  in 2002, scientists have observations they can use to constrain their models and improve their understanding of this complicated matter.

Further reading

Edited by Clara Burgard and Sophie Berger

The hidden part of the cryosphere – Ice in caves

The hidden part of the cryosphere – Ice in caves

The cryosphere can be found in various places in many forms and shapes… in the atmosphere, on land and sea. A lesser known part of the cryosphere is hidden deep in the dark, in the cold-karstic areas of the planet: Ice caves! The ongoing climate change affecting ice all over the world is now rapidly melting these hidden ice masses as well. We therefore need to hurry up and try to collect as much information as we can before all will melt away…


The big melting

The ice masses around the globe, in ice sheets, sea ice, and mountain glaciers, have been melting away in past decades (see this previous post). The reduction of the cryosphere, both in terms of area and mass, has particularly been visible in the European Alps over the last 30 years. On the one hand, large and small Alpine glaciers decline, fragment and even disappear, and this trend has accelerated since the mid 1980s. Mountain glaciers are therefore considered to be sensitive indicators for climate variability. On the other hand, the warming climate is also acting on permafrost degradation, mostly affecting the stability of rock-slopes and cliffs.

What makes the international scientific community worry at the moment is how fast this abrupt glacial reduction is occurring globally. However, not all the natural environments respond in the same way to sudden changes in the climate system! Fortunately for us scientists, there are physical environments and ecological niches more resilient to external perturbations. This aspect has sometimes allowed the preservation of environments and information in the Earth’s climatic history that would have been otherwise destroyed.

Caves are resilient

Among the most resilient natural environments there are caves, “protected” by the rocky mass within which they were formed. In the mountains, high-altitude karst cavities can contain huge deposits of ice representing a lesser known part of the cryosphere. Speleologists face such ice in caves both as a joy and a damnation: fascinating by their beautiful shapes and morphologies, they also see it as an unwieldy presence that prevents explorations of still unknown voids in the alpine karstic systems.

Fig. 2: An ice deposit in a cave of the southeastern Alps [Credit: Renato R. Colucci].

 

But ice in caves is not just something beautiful (but isn’t it? Look at Fig. 2!). It rather represents a precious natural archive, sometimes with high temporal resolution, able to tell the climate history of large part of the Holocene (the last 11700 years of the Earth’s history). The permanent ice deposits, i.e. the ice staying longer than just a winter season, often defined in a colorful way as “fossil ice” by speleologists, is what counts the most. As it typically gets older than 2 years, which is one threshold for the general definition of permafrost, this phenomenon is part of the mountain permafrost… right or wrong, ice in caves is ground ice!

Fig. 3: Huge entrance of a cave opening in the Dachstein limestones of the Canin-Kanin massif, southeastern Alps [Credit: Renato R. Colucci].

 

Generally in the Alps such ice deposits lie in caves having their opening at altitudes above 1,000 m (Fig. 3), but locally even lower. The formation of these unique environments depends on a combination of geomorphological and climatic characteristics, which allow for accumulation and preservation of ice also in places where this would be very unlikely.

Now, although the caves are resilient environments, ice melting due to climate change is rapidly increasing there as well. This is why it is important to save as much information as possible from the remaining ice, before it is definitely lost!

The C3 project – Cave’s Cryosphere and Climate

The C3-Cave’s Cryosphere and Climate project is under the scientific guidance of the National Research Council (CNR) of Italy, and precisely the climate and paleoclimate research group of ISMAR Trieste. It aims to monitor and study ice deposits in caves. Such ice deposits store several information related to the paleoclimate, the biology, the chemistry and ecology of these environments.

Fig. 4: Drilling ice cores with the aim to extract the CCC layer from this ice body in a cave of the southeastern Alps [Credit: Arianna Peron].

The project started in 2016, following the discovery of a coarse cryogenic calcite deposit (CCCcoarse) in an ice layer (in-situ) in a cave of the Canin-Kanin massif, in the Julian Alps, located between Italy and Slovenia. This finding, representing the first evidence of CCC in the southern Alps, provides an important opportunity to understand the processes associated to the formation of these particular calcite crystals (Fig. 4). Previously, the CCC (Fig. 5) was only found on the floor in caves where ice had already melted away. What makes it interesting is the fact that it is possible to date these crystals using the isotopic ratio of some trace elements in radioactive materials, typically Uran and Thorium.

Fig. 5: Millimetric crystals of coarse cryogenic calcite found in-situ in the southern Alps [Credit: Renato R. Colucci].

The strongest financial and logistic support to the project is given by the Alpine Society of the Julian Alps through its speleological group, the E. Boegan Cave Commission. In addition to the CNR and other Italian institutions such as the University of Trieste, University of Bologna, Insubria University in Varese, Milano Bicocca University and the Natural Park of the Julian Prealps, the project involves research institutes and universities from Germany (Institute of Physics of Heidelberg University), Switzerland (Paul Scherrer Institut; Swiss Institute for Speleology and Karst Studies), Austria (Innsbruck University; Palynology and Archaeobotany Research Group), and Slovenia (Geological survey of Slovenia).

Many activities and several results already unveiled few of the secrets hidden in such environments: the realization of the first thermo-fluido-dynamic model in an ice cave, the development of innovative techniques for studying the mass balance of the ice, the study of the thermal characteristics of the rock and therefore of the permafrost and the active layer, the development of innovative and multidisciplinary methods of ice dating.

But there is little time to do all, and we must exploit it to the fullest!

Further reading

Edited by Clara Burgard


Renato R. Colucci works in the climate and paleoclimate research group of ISMAR-CNR, Department of Earth System Sciences and Environmental Technology. He is also adjunct Professor of glaciology at the University of Trieste (Italy). During his PhD he honed his skills in glacial and periglacial geomorphology at UNIS (University Center in Svalbard). His research centers around the interactions between cryosphere (glaciers, permafrost, ice caves) and the climate, spanning from the end of the Last Glacial Maximum to the present days.

Image of the Week – When “Ice, Ice Baby” puts rocks “Under Pressure”

Image 1: Composite image of the Aiguille Verte, the heavily-fractured headwall of the Glacier d’Argentière near Chamonix, France [Credit: D. Dennis].

Bowie and Queen said it first, and Vanilla Ice brought it back. But now, I’ve set out to quantify it: Pressure. Rocks in glacial landscapes can experience many different kinds of pressure (forces), from sources like regional tectonics or even the weight of the glacier itself. Our hypothesis is that smaller-scale pressures, caused by the formation of ice in small bedrock cracks (frost-weathering), have a large effect on the sculpting of landscapes in cold regions. This post will share how we evaluate these processes and their dependence on temperature, as well as discussing the broader effects for glacier and glacial landscape evolution.


Walking through the valley in the shadow of glaciers

Growing up just outside Glacier National Park, USA, at nearly the exact edge of the former Laurentide Ice Sheet, I became familiar with the romantic lore of how we understand glacial landscapes (Images 2, 3). Observing these glacial landscapes later throughout my formal Earth science education, I came to understand mountains as passive resistors to the relentless efficiency of glacier advance, erosion, and retreat—offering evidence of past glaciations but nonetheless devoid of agency in the rise and fall of icy stadials.

My current PhD research, however, investigates a slightly-modified premise: that glaciers and their landscapes respond in concert with climate, and that dividing the dynamics governing the ice and the rock may not be as straightforward as once thought. My work is a sub-project of the Climate Sensitivity of Glacial Landscape Dynamics (COLD) project, funded by the European Research Council (ERC) and lead by Dirk Scherler at the Deutches GeoForschungsZentrum (GFZ) in Potsdam, Germany.

Image 2: The author on holiday in Glacier National Park, Montana, circa 2001, demonstrating an early aptitude for glacial geomorphology and cosmogenic nuclide geochemistry. His affinity for popular German footwear at a young age foreshadowed his eventual move to Germany to study glaciology and geomorphology [Credit: D. Dennis].

Image 3: This image of Chamonix Valley and the M. Blanc massif conceptually outlines how average annual temperature may change with elevation in steep hillslopes. The highest peaks in the massif tower up to nearly 4000 m over Chamonix Valley, which sits at appx.1000m. This corresponds to a nearly ~20 °C difference in annual average temperature. [Image adapted from Google Earth].

Temperature as a control in glacial landscapes

Glaciers exist in locations with temperatures that are, for some portion of the year, below freezing, as this is a condition required for snow to persist through the melt season and to form ice. Temperature is therefore an important primary control on the stability of glaciers. These cold temperatures, however, impact mountain environments beyond just the formation/decline of glaciers, and several decades of recent research have shown that temperature is an important controlling factor on the type and magnitude of erosion (the act of dislodging and transporting rock) in cold landscapes.

Mountain glacier valleys are commonly characterized by steep head- and sidewalls which frame the glacier within (like in our Image of the Week). At our field sites in the French, Swiss, and Italian Alps, these rockwalls can tower up to 1500 m above the surface of the glaciers, corresponding to a temperature gradient of ~10 degrees (Image 3). Therefore, the rocks at different elevations are exposed to different temperature conditions, which could lead to differences in the rate of erosion.

Image 4: Permafrost degradation and frost-weathering in the steep hillslopes of the M. Blanc massif commonly lead to the deposition of debris on the glaciers at the base of the mountains. Shown here is Glacier d’Argentière (France) with patches of surface debris [Credit: D. Dennis].

Erosion in steep rockwall faces

Frost-weathering processes occur only at temperatures at or below zero, therefore requiring the same cold temperature conditions that form glaciers. At these temperatures, liquid water present in small cracks in the bedrock freezes. The pressure exerted on the rock by the ice as it freezes causes the rock to fracture, leading to large cracks in the bedrock (Image 5). Erosion occurs when the ice in the crack becomes large enough and its corresponding fracture wide enough that the rock can no longer remain attached and it falls from the rockwall surface.

Erosion can also occur when the ice in the crack melts and no longer “cements” the surface together. Because temperatures in glacial landscapes are commonly quite cold, much of the bedrock is considered permafrost (permanently-frozen ground), and remains frozen throughout the year. In the Alps, however, warmer temperatures over the past decades have caused the permafrost to thaw, melting the lenses of ice and causing larger and more frequent rockfalls.

Temperature conditions are therefore important for both the rate at which cracks form in rocks (and erode from the surface) in addition to permafrost stability and the size/frequency of rockfalls. As temperatures change in mountain regions due to global warming, this could lead to considerable changes in debris production.

Image 5: A cropped version of our Image of the Week, showing the base of the Aiguille Verte, headwall of Glacier d’Argentière. Large fractures in the bedrock are clearly visible. These may have grown from much smaller cracks that formed due to frost-weathering.

The hillslope/glacier surface connection

After material erodes from the surface of the headwall, it is often deposited onto the surface of the glacier (Image 3). As mentioned above, the deposition of material can occur both at a constant rate or sporadically (as in the case of permafrost-thaw rockfalls), depending on the controlling process. As such, determining the actual representative rate at which these headwalls erode is challenging.

Though this work can be complicated, we believe it to be important, as debris deposited on the surface of glaciers can insulate the ice from the effects of temperature (Image 4, Video 1). Though the global distribution of debris-covered glaciers is much smaller than debris-free glaciers, debris-covered glaciers make up a non-trivial fraction of the glaciers in populated mountain regions where they may be important fresh water sources, contribute to glacial hazards, or allow for the generation of hydropower. Understanding the supply of debris to these glaciers (via erosion), and how it may change, is therefore an important component of forecasting their evolution under warming climates.

Video 1: This drone footage from the Arolla Glacier, Switzerland, shows the steep relief which can develop as a result of differential melting. Debris thicker than 2-4 cm insulate ice, leading to topographic relief on the glacier surface as exposed ice melts and covered ice is protected. [Credit: D. Gök, GFZ]

Re-evaluating the dynamic glacial landscape

Though studies of frost-cracking and debris-covered glaciers individually are not necessarily brand new inventions, our methods for combining the two are rather novel. In doing so, we are linking the evolution of glacier with the evolution of the landscape itself, and investigating an interesting feedback loop induced by changes in climate. Should erosion rates increase with warmer temperatures, and the mountains therefore supply more debris to glacier surfaces, this could extend the “lifetime” of the glacier by insulating it; likewise, if erosion rates decrease, less debris supplied to already-covered glaciers could lead to less insulation and (comparatively) higher melt rates. This interplay demonstrates the complexity of Earth system processes, and the need to take these complexities into account when considering the effects of climate changes.

To summarize

Pressure, pushing down on rock,
Pushing laterally against rock, can cause them to fall.
Under (thick) debris, glacier melt will slow,
Despite higher temperatures,
And global warming.

Will it ever stop? I don’t know.
Turn up the temperatures, then no more (ice and) snow.
At the end of the day, frost-weathering needs ice,
When water can’t freeze, ice-cracking’s no dice.

Edited by David Docquier


Donovan Dennis is a PhD student at the Deutches GeoForschungsZentrum in Potsdam, Germany. He is interested in many aspects of glaciology and glacial geomorphology, and currently investigates the geomorphic feedbacks on glacial landscape erosion. He previously worked on post-deposition alteration of stable water isotope signals in snow and ice. He tweets as @donovan__dennis.

Contact Email: dennis@gfz-potsdam.de

 

Image of the Week – Seven weeks in Antarctica [and how to study its surface mass balance]

Figure 1 – Drone picture of our field camp in the Princess Ragnhild coastal region, East Antarctica. [Credit: Nander Wever]

After only two months of PhD at the Laboratoire de Glaciologie of the Université libre de Bruxelles (ULB, Belgium), I had the chance to participate in an ice core drilling campaign in the Princess Ragnhild coastal region, East Antarctica, during seven weeks in December 2018 – January 2019 for the Mass2Ant project. Our goal was to collect ice cores to better evaluate the evolution of the surface mass balance in the Antarctic Ice sheet. Despite the sometimes-uncomfortable weather conditions, the ins and outs of the fieldwork and the absence of friends and family, these seven weeks in Antarctica were a wonderful experience…


Mass2Ant

Mass2Ant is the acronym of the project: “East Antarctic surface mass balance in the Anthropocene: observations and multiscale modelling”. This project aims to better understand the processes controlling the surface mass balance in East Antarctica, its variability in the recent past and, ultimately, improve the projections of mass balance changes of the East Antarctic ice sheet.

What exactly is the surface mass balance?

The mass balance of an ice sheet (see Fig. 2) is the net balance between the mass gained by snow accumulation and the loss of mass by melting (either at the surface or under the floating ice shelves) and calving (breaking off of icebergs at the ice shelves fronts).

The surface mass balance on the other hand only considers the surface of the ice sheet. It is thus, for a given location, the difference between:

  • incoming mass: snowfall, and
  • outgoing mass, due to melting processes (fusion and sublimation), meltwater runoff and transport or erosion by wind at the ice sheet interface.

Figure 2 – Representation of the mass balance of an ice sheet [Credit: Figure adapted from NASA, Wikimedia Commons].

Overall, the ice sheet mass balance – the principal indicator of the “health state” of an ice sheet – is the balance between the surface mass balance, iceberg calving and basal melt under the ice shelves. A good evaluation of these three factors is thus essential to better quantify the evolution of the Antarctic mass balance under anthropogenic warming and therefore its contribution to future sea level rise.

However, the surface mass balance is characterized by strong temporal and spatial variations (see Figure 3) and is poorly constrained. In order to improve future projections for Antarctica, it is essential to better assess the variability of the Antarctic surface mass balance by directly collecting data in the field. Within this framework, the goal of the Mass2Ant project is to study the surface mass balance in the Princess Ragnhild coastal region (marked in the Figure 3).

Figure 3 – Surface mass balance (1989-2009) from RACMO2 (a regional climate model) of Antarctica (left) and Greenland (right) in kg/m².yr. Contour levels (dashed) are shown every 500 m. Black dot is the approximative position of the drilling site on the Tison Ice Rise. [Credit: adapted from Figure 1 of van den Broeke et al. (2011)].

Collecting the data [or how can we use ice cores to infer surface mass balance?]

Surface mass balance can be determined by analyzing ice core records. As a part of our expedition, ice cores were collected on the summit of the so-called “Tison Ice Rise” (a non-official name) – 70°S 21°E, near the Belgian Princess Elisabeth Station. We drilled to a depth of 260.1 m, which we expect to date back to the 15th century.
The drilling system, named the Eclipse drill, contains a motor on top of a drill barrel – which is composed of an inner barrel that cuts the ice core with 3 knives and collects it and an outer barrel (a tube) that collects the chips created. Due to the overlaying ice, pressure increases very quickly with depth. Deep ice cores are thus subject to much higher pressure than the atmospheric pressure. In order to reduce these strong pressure differences as the ice core is brought to the surface, drilling fluid was poured in the boreholes, a technique called “wet-drilling”. This was the first time the wet-drilling technique was used by our team, and it significantly improved the quality of our ice cores compared to the traditional method used during the previous campaigns!

Figure 4 – A part of our team in the drilling tent. An ice core can be observed in the inner barrel of the drilling system. A wooden box is placed on top of the trench, under the drill barrel to collect the chips contained in the outer barrel. [Credit: Hugues Goosse]

The 329 collected ice cores will be analyzed in our lab in Brussels. More specifically, we will focus on

  • the water stable isotopes: the seasonal cycle of stable isotopes of water in ice will be used for relative dating of the ice core;
  • the major ions (Na+, nssSO4, Na+/SO42-, NO3…) present in the ice: the reconstruction of the seasonal cycle of these ions allows us to refine the isotopic dating and therefore infer the annual snow/firn/ice thickness.
  • the conductivity of the ice, which also shows a clear seasonal signal used for dating. Moreover, the conductivity signal is also reacting to localized extra inputs – for example from past volcanic eruptions – therefore providing an absolute dating, which reduces our dating method uncertainties.

The seasonality of these signals will allow us to infer the yearly ice thicknesses (see this post). By taking into account the deformation of the ice, we will then be able to reconstruct the evolution of the surface mass balance in the Princess Ragnhild Coast region since the 15th century.

Life in the field

What was a typical day like for us? In fact, it strongly depended on the team to which you belonged as we were divided into two groups:

  • The “day group” was working on measurements such as snow density and radar analyses and worked roughly between 8 AM and 8 PM.
  • The second group – the drilling team, including me – worked during nights (between 9 PM and 9 AM) because of the too high temperatures during day, which would lead to ice core melt.

The drilling team adapted quite easily to this timing as the sun was shining 24 hours a day. In order to spend a common moment, a joint meal was organized every day at 8.30 AM, with some of us having their dinner while others were having breakfast.
The everyday life mainly occurred in two equipped containers. The first container was our living space, which we used as kitchen, dining room and working space. The second container consisted of a cloakroom, the toilets and the bathroom (with a real shower, a luxury in the field!). Each of us had a tent to sleep, with adapted sleeping bag, making it quite comfortable. As we stayed 5 weeks at the drilling site, we spent Christmas and New Year’s Eve on the field. It was a good occasion to eat fondue while sharing some fun stories and jokes (Fig. 5).

Figure 5 – Christmas time spent together, giving presents and eating fondue. [Credit: Nander Wever]

Why should you too go to Antarctica?

I’ll keep many memories of the time we all spent together, but also of the amazing landscapes and the calm and peacefulness of this white immensity… Despite the sometimes-uncomfortable weather conditions (a full week of whiteout days, lucky us!), this unique experience was wonderful! I’ve learned so much, from a scientific but also personal point of view. It was also a chance to participate in the collection of the samples that I will study during the next four years of my PhD. Before I left for Antarctica, someone told me that “When you went to Antarctica once, you usually want to go again”. Well, that’s definitely true for me!

Many thanks to belspo for funding this project, to the International Polar Foundation and Princess Elisabeth Antarctica staffs for the work both in Cape Town and in the station, and last but not least, thanks to the Mass2Ant team in the field that made this experience an amazing adventure.

Further reading

Edited by Violaine Coulon


Sarah Wauthy is a PhD student at Laboratoire de Glaciologie, Université Libre de Bruxelles, Belgium. Her PhD is part of the Mass2Ant project and aims at determining paleo-accumulation in the region of the Princess Ragnhild Coast (Dronning Maud Land, East Antarctica) as well as the paleo-extension of sea ice before and across the Anthropocene transition (ca. last 3 centuries), by performing high-resolution multiparametric analyses on ice cores collected during field campaigns.

Image of the Week – We walked the Talk to Everest

Fig. 1: Group photo with Mount Everest backdrop following presentations at the Sagarmatha National Park office in Namche Bazar (3,500 m a.s.l) with 60 participants (wrapped up against the cold temperatures). [Credit: Dhananjay Regmi].

The 12 day “Walk the Talk” Field Conference and Community Consultation through Sagarmatha National Park, Nepal, discussed a wide range of research outputs with local communities, tourists, and officials. Topics covered glaciers, mountains, environmental and landscape change, Sherpa livelihoods, tourism, and natural hazards. The conference, organised by Himalayan Research Expeditions, was the first of its kind, designed to receive community input into research topics and pursue applied benefits. Scott and Katie were two of the participants, presenting work from their PhDs in the Everest region and the NERC-funded EverDrill project.


Presentations and discussions

The team of international and Nepali scientists gave presentations every evening, trekking each day between six different villages along the Everest Base Camp trail. We were also joined by officials from the Nepal Department of Tourism and the Mountain Institute. The highest destination for the conference was Imja Glacial Lake, at over 5,000 m elevation, where we viewed first-hand the results of a recent $7 million project to lower the lake water level, aiming to reduce the risk of an outburst flood.

The Sagarmatha National Park has been a focus for scientists of many disciplines for decades. As well as thousands of tourists trekking to Everest Base Camp each year, it is also frequented by those hoping to summit Mount Everest (Sagarmatha). The park has therefore experienced significant change over a relatively short timescale as it copes with this huge influx of people. Presentations for the “Walk the Talk” conference ranged from impacts of tourism (for example, on local people, yak breeding and waste disposal) to natural hazards such as glacial lake outburst floods and landslides.

Katie presented ongoing work from her PhD and the “EverDrill” project (Fig. 2), for which she has conducted several field seasons on Khumbu Glacier in the Sagarmatha National Park. Fieldwork has included hot-water drilling of boreholes into the glacier and installing sensors to measure ice temperature at various depths to investigate the glacier’s thermal regime. She discussed how these measurements showed that Khumbu’s ice is warmer than expected, potentially putting the glacier at risk of more rapid melting as air temperatures rise. The warmer ice towards the terminus also allows subsurface meltwater drainage, about which very little is known. Katie has also carried out fluorescent dye tracing experiments to work out how meltwater travels through Khumbu Glacier, including storage within (englacial) and on the surface (supraglacial). As Khumbu and similar glaciers retreat in the future, meltwater storage and runoff will have implications for the downstream communities who depend on such water sources.

Fig. 2: Katie presenting measurements of Khumbu Glacier’s thermal regime and hydrology at the Sagarmatha National Park headquarters in Namche Bazar (3,500 m a.s.l.). [Credit: Dhananjay Regmi].

Scott presented results from his PhD investigating melt processes and water storage on Khumbu Glacier (Fig. 3). Areas of Khumbu Glacier have thinned by up to 80 m over the last three decades and glacier flow is slowing down, which allows meltwater to pond on the glacier surface. The rugged glacier surface is pitted with ice cliffs and ponds, which act as hot-spots of melt in areas of the glacier otherwise insulated by a thick layer of rocks and sediment (debris-cover). The rapid formation, persistence, and drainage of meltwater stored on glaciers across the Himalaya is a growing concern due to the potential for outburst floods and increased rates of glacier melt. An outburst flood event that occurred in the Everest region in 2017 destroyed trekking trails and a bridge.

Fig. 3: Scott presenting a study of glacier thinning at the Sagarmatha National Park office in Namche Bazar (3,500 m a.s.l). [Credit: Dhananjay Regmi].

After the final day of trekking, an extra night was spent in the village of Lukla, before flying back to Kathmandu. Each presentation was summarised in a few slides, and collated into a full talk that was given in Nepali by Dr. Dhananjay Regmi, organiser of the conference and head of Himalayan Research Expeditions. By presenting all our research in Nepali, more local people attended and were able to hear about and suggest new directions for research in the valley. This presentation was given again two days later, also in Nepali, at the Department of Tourism in Kathmandu, for locals who had already travelled back to the city to avoid the high-elevation winter chill.

Outreach activities

Fig. 4: The projection augmented relief model shown after presentations in the village of Phortse. The inset shows glacier velocity data projected onto the glaciers in the Everest region. [Credit: Gu Changjun and Scott Watson].

We designed outreach activities and leaflets to enhance the PowerPoint presentations given at each village by providing interactive demonstrations of key research concepts and results. Scott used an AGU Celebrate 100 grant to design a projection augmented relief model (PARM) of the Everest region (Fig. 4). The PARM system projected research results including glacier velocity, mass loss, ice thickness, temperature, and animations of glacier flow, onto a 3D model, which stimulated discussion of the research. The 3D model allowed the local communities to easily visualise the data in the context of well-known mountain peaks and glaciers, and to observe the changing environment (such as the expansion of Imja Lake) from a projected time-lapse animation.

Fig. 5: Katie demonstrating glacier thermal regime and hydrology using a 3D model to conduct example dye tracing experiments. The lower panel is a GIF showing the dye tracing. [Credit: Scott Watson and Katie Miles].

Katie’s interactive outreach was to demonstrate dye tracing experiments on a 3D model of Khumbu Glacier (Fig. 5). Food colouring was used to “dye” the water, which was “injected” into a supraglacial stream, then “disappeared” into the glacier. The side view into the glacier showed this water flowing through and beneath the ice, before emerging back at the surface, flowing through surface ponds and exiting the glacier at its terminus. The side view also showed the approximate ice temperatures measured by the EverDrill project, which actively showed where (and why) the glacier is experiencing more melt.

The model was very well received by scientists and locals – while the water was being injected, we would explain what was happening in both English and Nepali, and there were always plenty of questions. While the dye tracing experiments didn’t work perfectly every time, surface floods offered an opportunity to talk about other hazards that have been recently observed on Khumbu Glacier.

Summary

The “Walk the Talk” Field Conference and Community Consultation was a new style of conference, aiming to communicate a wide range of research topics in the Everest region of Nepal and the Sagarmatha National Park. The combination of high-elevation trekking and presentations was sometimes tiring, but the trek facilitated discussions about the landscape we were immersed in and was a fantastic learning experience. It is hoped that the conference will travel to different locations in the future to share research and understand the priorities of other communities in Nepal.

Further reading

Edited by Violaine Coulon


Scott Watson is a Postdoc at the University of Arizona, USA, studying glaciers in the Everest region and the surface interactions of supraglacial ponds and ice cliffs. He also investigates natural hazards and glacial lake outburst floods. Tweets @CScottWatson. Website: www.rockyglaciers.co.uk

 

 

 

Katie Miles is a PhD student at the Centre for Glaciology, Aberystwyth University, UK, studying the internal structure and subsurface hydrology of high-elevation debris-covered glaciers in the Himalaya through borehole-based investigations and dye tracing experiments. Tweets @Katie_Miles_851. EverDrill website: www.EverDrill.org

Image of the Week – Delaying the flood with glacial geoengineering

Figure 1: Three examples of glacial geoengineering techniques to mitigate sea-level rise from ice-sheet melting [Credit: Adapted from Figure 1 of Moore et al. (2018); Design: Claire Welsh/Nature].

As the climate is currently warming, many countries and cities are preparing to cope with one of its major impacts, namely sea-level rise. Up to now, the mitigation of climate change has mainly focused on the reduction of greenhouse gas emissions. Large-scale geoengineering has also been proposed to remove carbon from the atmosphere or inject aerosols into the stratosphere to limit the rise in temperature. But locally-targeted geoengineering techniques could also provide a way to avoid some of the worst impacts, like the sea-level rise. In this Image of the Week, we present examples of such a technique that could be applied to the Antarctic and Greenland ice sheets (Moore et al., 2018; Wolovick and Moore, 2018).


Sea level is rising…

The sea level of the world oceans has been rising at a mean rate of 3 mm per year since the 1990s, mainly due to ocean thermal expansion, land-ice melting and changes in freshwater storage (see this post). More than 90% of coastal areas could experience a sea-level rise exceeding 20 cm with a 2°C warming (relative to the pre-industrial period), which is likely to happen by the middle of this century (Jevrejeva et al., 2016).

The Antarctic and Greenland ice sheets constitute two huge reservoirs of ice and contain the equivalent of 60 and 7 m of sea-level rise, respectively, if completely melted. Although a complete disintegration of these two ice sheets is not on the agenda in the coming years, surface melting of the Greenland ice sheet and the flow of some major polar glaciers could be enhanced by different positive feedbacks (see this post on climate feedbacks and this post on marine ice sheet instability). These feedbacks would elevate the sea level even more than projected by the models.

… but could potentially be delayed by glacial geoengineering

In order to cope with this threat, reducing our greenhouse gas emissions might not be sufficient to delay the rise of sea level. One alternative has been suggested by Moore et al. (2018) and consists of using glacial geoengineering techniques in the vicinity of fast-flowing glaciers of the Antarctic and Greenland ice sheets. They propose three different ways to delay sea-level rise from these glaciers and these are presented in our Image of the Week (Fig. 1):

A.   A pumping station could be installed at the top of the glacier with the aim of extracting or freezing the water at the glacier base. This would slow down the glacier sliding on the bedrock and reduce its contribution to sea-level rise.

B.   An artificial island (about 300 m high) could be built in the cavity under the floating section of the glacier (or ice shelf). This would enhance the so-called buttressing effect (see this post) and decrease the glacier flow to the ocean.

C.   A wall of up to 100 m high could be built in the ocean bay right in the front of the ice shelf. This would block (partially or completely) any warm water circulating underneath the ice shelf and delay the sub-shelf melting (see this post).

In theory

Wolovick and Moore (2018) studied in detail the possibility of building artificial islands (proposal B above) underneath the ice shelf of Thwaites Glacier (West Antarctica), one of the largest glacier contributors to the ongoing sea-level rise. They used a simple ice-flow model coupled to a simple ocean model and considered different warming scenarios in which they introduced an artificial island underneath the ice shelf.

Figure 2 below illustrates an example coming from their analysis. In the beginning (Fig. 2b), the grounding line (separation between the grounded ice sheet in blue and the floating ice shelf in purple) is located on top of a small mountain range. When running the model under a global warming scenario, the grounding line retreats inland and the glacier enters into a ‘collapsing phase’ (Fig. 2c; marine ice sheet instability). The introduction of an artificial island under the ice shelf with a potential to block half the warm ocean water allows the ice shelf to reground (Fig. 2d; the ice-shelf base touches the top of the small island below). The unprotected seaward part of the ice shelf shrinks over time, while the protected inland part thickens and regrounds (Fig. 2e-f), which overall decreases the glacier mass loss to the ocean.

Figure 2: Example of a model experiment realized on Thwaites Glacier by Wolovick and Moore (2018). Different times are presented and show the (b) initial state, (c) the collapse underway, (d) the initial effect of the construction of the artificial island below the ice shelf, (e) the removal of the seaward ice shelf and thickening of the landward ice shelf, (f) the stabilization of the glacier [Credit: Figure 5 of Wolovick and Moore (2018)].

In practice

The model experiments presented above show that delaying sea-level rise from glacier outflow is possible in theory. In practice, this would mean substantial geoengineering efforts. For building a small artificial island under the ice shelf of Pine Island Glacier (West Antarctica), 0.1 km3 of gravel and sand would be necessary. That same quantity would be sufficient to build a 100 m high wall in front of Jakobshavn Glacier (Greenland) to prevent warm water from melting the ice base. For building such a wall in front of Pine Island Glacier, a quantity of 6 km3 (60 times more than Jakobshavn) of material would be needed.

In comparison, the Three Gorges Dam used 0.03 km3 of cast concrete, the Hong Kong’s airport required around 0.3 km3 of landfill, and the excavation of the Suez Canal necessitated 1 km3 of material. Thus, the quantities needed for building glacial geoengineering structures are comparable in size to the current large engineering projects.

However, many other aspects need to be considered when implementing such a project. In particular, the construction of such structures in cold waters surrounded by icebergs and sea ice is much more difficult than in a typical temperate climate. A detailed study of physical processes in the region of the glacier, such as ocean circulation, iceberg calving, glacier sliding and erosion, and melting rates, is needed before performing such projects. Also, the number of people needed to work on a project of this scale is an important factor to include.

Potential adverse effects

Beside all the factors that need to be considered to implement such a project, there is a list of potential adverse effects. One of the main risks is to the marine ecosystems, which could be affected by the constructions of the islands and walls. Also, if not properly designed, the geoengineering solutions could accelerate the sea-level rise instead of delaying it. For instance, in the case of water extraction (proposal A above), the glacier might speed up rather than slow down if water at the glacier’s base is trapped in pockets.

Wolovick and Moore (2018) do not advocate that glacial geoengineering is done any time soon, due to the different factors mentioned above. Instead, they suggest that we start thinking about technological solutions that could delay sea-level rise. Other studies also look at different glacial geoengineering ideas (see this post).

In summary

Glacial geoengineering techniques constitute a potential way to cope with one of the greatest challenges related to global warming, namely sea-level rise. In theory, these projects are possible, while in practice a series of technical difficulties and potential ecological risks do not allow us to implement them soon.

While important to keep thinking about these solutions, the most important action that humanity can take in order to delay sea-level rise is to mitigate greenhouse gas emissions. And scientists like us need to keep carefully studying the cryosphere and the Earth’s climate in general.

Further reading

Edited by Jenny Turton


David 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 – Why is ice so slippery?

Ice can be slippery! [Credit: giphy.com]

Having spent most of my life in places where the temperature hardly ever falls below zero, my first winter in Sweden was painful. Especially for my bum, who met the ice quite unexpectedly. Reading the news this week, from reports of emergency services overwhelmed after so many people had slipped to a scientific study on how no shoes have a good enough grip, via advice on how to walk like a penguin, I understand I am far from alone in having a problem with ice. But why is ice so slippery anyway? This is what we will talk about in this Image of the Week.


Did you know that you lacked friction?

To understand why one might fall sometimes, let us start with why one usually can walk without falling: friction! Friction is a resistive force that can have three causes:

  • Adhesion (think about glue or tape)

  • Surface roughness (think about sandpaper)

  • Deformation (think about dragging a suitcase over a gravel path)

Each of these types of friction is nicely explained on this website, so I will concentrate on our walking question. Note that if you are standing still, it is a different story; then we are talking about static (instead of dynamic) friction. And everything is actually a bit more complicated than the distinction between the three causes, since adhesion and roughness are somehow related. I will not get into that, but if that stirred your interest, you could have a look at this paper. Anyway, back to walking.

The roughness of our roads and pavements, along with that of your shoes and their deformation ability, is, of course, crucial. But in the case of water after the rain or rotten autumn leaves, adhesion can be the deciding factor between casually walking and experiencing a sudden unexpected loss of altitude: not that much adhesion between your foot and what you walk on, but rather between what you walk on and the rest of the world. And that is exactly the problem with ice.

Frozen lake [Credit: Nilay Dogulu (distributed via imaggeo.egu.eu)]

Water really is a weird material

Coming from a place where people rarely worry about ice, I had never heard the commonly accepted reasons why ice is slippery. A quick internet search informed me that a common belief is that ice is slippery because, by walking on it, we melt the very surface of the ice through the pressure of our weight and/or the heat of the friction. As a result, we end up with a dangerous layer of liquid water between our foot and the ice, lose adhesion, and … boom! A study published this summer has a different explanation: water in its solid form is made of chains of molecules attached to three other water molecules. But the chain has to stop somewhere, so, at the very surface, molecules are only attached to one or two others, and can, as a result, be easily detached from the rest of the ice. When that happens, they just hang around on top of the ice, “like marbles on a dancefloor“.

However, it cannot be seen as a layer of liquid water, rather as a gas, the authors of that new study say. Not that it makes a big difference when you are on the floor… The good (?) news is, this strange property of ice depends on temperature. They report that ice is the most treacherous at -7°C, but then becomes safer as the temperature decreases.

EGU Cryosphere friendly advice: how to walk around -7°C

Personally, I avoid roads and pavements like the plague and walk on frozen paths and grass, which retain some roughness unless covered by a lot of snow. Since it is not always possible, adopt the technique of our favourite polar animal:

  • put your centre of mass ahead of you by slightly bending your torso forward

  • go slowly

  • move your foot next to each other, instead of in front of one another

  • or give up and slide on your belly!

One of our favourite polar animals [Credit: Giuseppe Aulicino (distributed via imaggeo.egu.eu)].

Further reading

Edited by Clara Burgard

Image of the Week – What’s Hot in the Cryosphere? A 2018 review

Image of the Week – What’s Hot in the Cryosphere? A 2018 review

Every year, humanity understands more and more about a remote and unforgiving component of the Earth system – the cryosphere. 2018 has been no exception, and in this blog post we’ll take a look at some of the biggest scientific findings of cryospheric science in 2018. We will then look forward to 2019 and beyond, to see what the future holds for these rapidly changing climate components.


The Cryosphere at 1.5°C warming

In 2018, the IPCC (Intergovernmental Panel on Climate Change) released their report that looked at the impact of 1.5 and 2.0°C of global warming by 2100 on the Earth system. In the Arctic, warming is already in excess of 2.0˚C, driving a very strong decreasing trend in the summer sea-ice extent. The IPCC suggest that sea-ice-free summers will occur once per century at 1.5°C, but this increases to once per decade at 2.0°C. Limiting warming to 1.5˚C will also save 1.5-2.5 million km2 of permafrost thaw (preventing the release of ancient carbon into the atmosphere), 10 cm of sea-level rise contribution from ice sheets and glaciers, and reduce the risk of the irreversible collapse of the ice sheets. Read more about the cryosphere under 1.5°C warming in this previous post.

 

Mass Balance of the Antarctic Ice Sheet

Compiling 24 independent estimates of mass balance, from a number of different remote sensing and modelling techniques, the IMBIE team produced the best estimate of how Antarctica is responding to continued climate warming. The mass balance refers to the net change in ice mass, accounting for all of the inputs and outputs to the ice. They quantify that ice mass loss from West Antarctica has increased three-fold between 1992 and 2017, largely due to melting from a warmer ocean. On the Antarctic Peninsula, the collapse of ice sheets has led to an increase ice mass loss by a factor of 4. East Antarctica is gaining mass slightly, although this is highly uncertain, by 5 ± 46 billion tonnes per year. Overall, Antarctica has lost 2,720 ± 1,390 billion tonnes of ice in this 25-year time period, and this mass loss is accelerating. Read more about these results in this previous post.

Mass loss from the Antarctic ice sheet is accelerating, largely due to ocean warming impacting West Antarctica. East Antarctica is very slightly gaining mass, but this doesn’t go anywhere near balancing out mass loss across the continent [Credit: NASA Goddard].

A polluted cryosphere

It’s easy to think of the cryosphere as a pristine, beautiful, untouched landscape. However, research from 2018 has shown us that the remoteness of Polar Regions has not protected them from man-made pollution. In one litre of melted Arctic sea-ice, 234 particles of plastic and over 12,000 particles of microplastics were found, which will only go onto adversely impact Arctic wildlife by spreading through the ecosystem. Radioactive material from the Chernobyl accident has also been found to be concentrated in dark sediments found on Swedish glaciers. As these glaciers melt, this concentration of radioactive material may be released in meltwater. In Greenland, lead pollution found in ice cores has provided exciting new insight into wars, plagues and invasions during the Roman Empire.

In 2018, we saw a glimpse of the geological secrets that Greenland hides beneath its ice sheet. However, there is still a hidden world that future field-based campaigns or airborne radar missions will help to unravel [Credit: NASA Goddard].

What secrets is Greenland hiding?

In 2018, we got our best ever look beneath the Greenland ice sheet. Scientists from the British Antarctic Survey and NASA found that the hotspot (a thermal plume in the Earth’s mantle) currently under Iceland was once beneath Greenland, between 80 to 50 million years ago. This hotspot was discovered by studying the magnetism of minerals beneath the ice. Using airplanes, radio waves and sediment that’s washed out from underneath the ice sheet has also revealed a massive 31 kilometre wide meteorite crater underneath Hiawatha glacier. Given it’s beneath three kilometres of ice, the age of this crater is unknown, but given the interest and speculation in connecting this event to an abrupt cooling period 12,000 years ago (the Younger Dryas), we may know very soon.

 

Blast Off!

Satellites remain one of the most popular methods of monitoring the vast, hostile cryosphere. In 2018, a new generation of earth observation missions launched. ESA’s Sentinel-3B continues the Copernicus programme, monitoring the reflectivity of the ice, elevation and sea-ice thickness. NASA’s GRACE FO mission continues the successful first GRACE mission, which used gravimetry to ‘weigh’ different regions of ice. NASA also launched ICESat-2, which will provide global elevation data at unprecedented spatial resolution on a 91-day repeat orbit. Each satellite is being finely tuned to make sure it’s working exactly as intended, and we’ll get the first science from them in 2019. Stay tuned!

Remote sensing data has provided us with answers to some of the biggest questions in the cryosphere. We use it to help quantify mass loss, sea-level rise and glacial retreat. In 2019, new missions will take our knowledge of cryospheric sciences to new heights! [Credit: Liam Taylor]

A look ahead to 2019

On the ground, getting inside the ice will continue to provide fascinating insights into the history of the cryosphere – from reconstructing winds in sub-Antarctic islands using ice cores, to further insights deep inside the world’s highest glacier. As permafrost continues to thaw, we are likely to hear of more discoveries of woolly mammoths, ancient diseases and carbon release. The IPCC will also publish their special report devoted to The Ocean and Cryosphere in a Changing Climate, which will provide the best overall state of the cryosphere to date. And, of course, the infamously named ‘Boaty McBoatface’ will provide us with incredible data from beneath sea-ice and ice shelves when the RRS Sir David Attenborough is launched. 2018 has been a truly exciting year to be a cryospheric scientist, and 2019 looks set to be another hot one!

 

Edited by Adam Bateson


Liam Taylor is a PhD student at the University of Leeds and Centre for Polar Observation and Monitoring. His research looks at identifying novel remote sensing methods to monitor mountain glaciers for water resource and hazard management. He is passionate about climate change and science communication to a global audience, as an educator on free online climate courses and through his personal blog. You can find Liam on Twitter.

Image of the Week – Will Santa have to move because of Climate Change?

Santa Claus on the move [Credit: Frank Schwichtenberg, CC BY 3.0, Wikimedia Commons]

Because of global warming and polar amplification, temperature rises twice as fast at the North Pole than anywhere else on the planet. Could that be a problem for our beloved Santa Claus, who, according to the legend, lives there? It appears that Santa could very well have to move to one of its second residences before the end of this century. But even if he moves to another place, the smooth running of Christmas could be in jeopardy…


But…. Where does Santa live?

The most famous of Santa’s residence is in Lapland, Finland, at Korvatunturi. But since this area is a little isolated, Finns then moved it near the town of Rovaniemi. For Swedes, it’s in Gesunda, northwest of Stockholm. The Danes, them, are convinced that he lives in Greenland while according to the Americans, he lives in the town of North Pole, Alaska. In Norway, there is even disagreement within the country: some Norwegians believe he lives in Drøback, 50 km south of Oslo while other believe he lives in the Northernmost inhabited town in the world: Longyearbyen, Spitsbergen, where Santa even has its own postbox!
Even in the southern hemisphere, Christmas Island claims to be Santa’s second home.

Santa’s huge postbox in Longyearbyen, Spitsbergen [Credit: Marie Kotovitch] and Rovaniemi, Finland: the self-proclaimed “official hometown of Santa Claus” [Credit: Pixabay]

It seems that Santa Claus has many places to stay.. But according to the legend, Santa’s real permanent residence is in fact the true North Pole. However, as shown by the Arctic Report Card 2018, the Arctic sea-ice cover continues its declining trends, with this year’s summer extent being the sixth lowest in the satellite record (1979-2018). The latest IPCC 1.5°C warming special report states that “ice-free Arctic Ocean summers are very likely at levels of global warming higher than 2°C” relative to pre-industrials levels. Considering that the world is currently on course for between 2.6 to 4.8°C of warming relative to pre-industrial levels by 2100, Santa’s home is projected to sink into the Arctic Ocean before the end of the current century. It appears it would be time for Santa to start thinking about which one of his second residences he will choose to move to…

Will Santa have to find a new home? [Credit: Pixabay]

Rudolf might be in trouble…

Of course, if he moves away from the melting North Pole, Santa still needs snow at Christmas to be able to take off his sled. But, actually, this could become a problem.
This year, there was still no snow in Rovaniemi, Finland, the self-proclaimed “official hometown of Santa Claus”, by the end of November, making the local tourist attractions very worried. Luckily, it has now snowed there since, but how does this look like for the years to come? According to the latest Arctic Report Card, the long-term trends of terrestrial snow cover are negative.

Another problem which might complicate Santa’s work was underlined in a study published in 2016. This study showed that reindeers are getting smaller because of warmer Arctic temperatures. How come? During the long winter, reindeers are usually able to find their food (which consists of grasses, lichens and mosses) by brushing aside the snow that covers it. But because of the warmer temperatures, rain now falls on the existing snow cover and freezes. The animals’ diet is thus locked away under a layer of ice. As a result, reindeers are hungry and lose their babies or give birth to much leaner ones. The Arctic Report Card 2018 states that the population of wild reindeer in the Arctic has decreased by more than half in the last two decades.

All this is not going to get better, as Arctic temperatures for the past five years (2014-18) all exceed previous records. According to the Danish Meteorological Institute, in November 2016, Arctic temperatures were reaching an incredible peak at around -5°C while average temperature at this period usually is around -25°C.

Climate change also affects reindeers [Credit: Photo by Red Hat Factory on Unsplash]

Christmas trees also at risk!

You may say that Santa is Santa and that he will be able to find a solution to all these problems. Let’s hope you’re right! But another problem is looming on the horizon: you might soon not be able to welcome Santa in your own home as it should with a beautiful Christmas tree.

Indeed, this summer’s heat waves have strongly affected Christmas tree crops everywhere in Europe. Moreover, a 2015 study shows that native Scandinavian Christmas trees are also affected by climate change, and more specifically by reduced snowfall. The latter acts like an insulation layer which protects the roots from the cold winter.

We hope that this post has made you realize the urgency of the fight against global warming! However, in the meantime, don’t forget that the most important to spend a nice Christmas is the Christmas spirit! We wish you all a very merry Christmas and a wonderful new year!

As a little Christmas gift..

  • If you want to find out the truth about Santa’s real home, you can always check it by yourself by using the Santa Tracker by Google to follow Santa’s Christmas Eve trip and check where he comes back at the end of the night…
  • The highlights of the Arctic Report Card 2018 are summarized in this video.

Further reading

Edited by Clara Burgard

Image of the Week – Permafrost features disappearing from subarctic peatlands

Image of the Week – Permafrost features disappearing from subarctic peatlands

Some of the most remarkable, marginal features of permafrost – palsas – are degrading and disappearing metre by metre from North European peatlands, and are driven close to extinction by the climate change.


What are these permafrost features?

A palsa is a peat mound with an icy core, which stays frozen throughout summer due to the insulating property of dry peat. These mounds can rise up to 10 metres above the surface of surrounding mire (wet terrain dominated by peat-forming vegetation), and they may occur as just a single palsa, group of palsas or as an extensive, but not very high (ca. 1 to 2 m) peat “platform”. The occurrence of palsas is limited by such factors as: low mean annual air temperature (< 0 °C), low annual precipitation (< 500 mm) and at least 40–50 cm thickness of peat layer, which is needed to sufficiently insulate the core during summer (Seppälä, 2011).

The established theory on palsas formation (Seppälä, 2011) is the following:

  1. The formation of a palsa begins when a part of mire freezes deeper in a windblown area with thinner snow cover, which normally protects the ground below from freezing temperatures.

  2. If the frozen peat doesn’t melt completely during summer, an ice lens forms inside the peat layer resulting in uplifting of the mire surface in this area.

  3. In the following winters, the snow is even more likely to be windblown from the mound, which again fosters deeper penetration of frost and formation of new ice lenses.

  4. As soon as a part of mire rises above the water level, the vegetation starts to change and the peat dries out, which contributes to the survival of the ice core during summers.

 

Breaking of the surface and erosion is a natural “step” for mature palsas, when the permafrost has reached the mineral ground below the peat. The melting of a palsa is a form of thermokarst, i.e. thawing of ice-rich permafrost (see this post for more details about thermokarst).

Block-erosion of peat on ridge-type palsa in Nierivuoma mire in Enontekiö, Finland [Credit: Mariana Verdonen].

Palsa, peat hummock or permafrost plateau?

The terminology used when speaking about these permafrost mounds varies, usually according to the continent the research was conducted on or the background of the authors. The term “palsa” comes from Lapland, and was used by Sami and northern Finns to refer to “hummock rising out of a bog with a core of ice” (Seppälä, 1972). In Fennoscandia, this term is used commonly for all main types: ridges, mounds and plateau palsas, whereas in North America the more common terms are either ‘peat or permafrost plateau’ or ‘wooded palsa’ depending on the shape and vegetation cover of the feature (Luoto et al, 2004).

Degrading permafrost of Fennoscandia

More often than not, one may encounter a desolate sight in North European palsa mires: most of the permafrost mounds are degrading by block erosion and/or melting away as a result of thawing of their frozen core. The vegetation that once was growing on hummocks above the wet mire surface, is now dead black in shallow thermokarst ponds surrounding palsas here and there. Although, in some places the conditions may still be favorable for new palsas to form, the general picture is devastating. Palsas are disappearing in most of their area of existence, and it is happening fast.

Thawing palsas of Nierivuoma captured from drone in July 2018. This peatland sprawls across ~7 km2 and is the largest palsa mire in Finland [Credit: Timo Kumpula].

Why should we care?

As climatic change is likely to increase winter and summer precipitation, and is already notable in rising mean annual air temperatures, palsas are predicted to disappear in Fennoscandia almost completely by the end of the 21st century (Fronzek et al, 2010).

It is noteworthy, that the palsa mire is the only mire and bog habitat that is listed as “critically endangered” in the 2016 European Red List of Habitats. While some other cold climate ecosystems may shift to higher latitudes and altitudes, palsa mires seem to be restricted from developing in higher areas, especially because of the required peat layer thickness (Luoto et al, 2004).

If just the loss of this diverse ecosystem type is not alarming by itself, there are couple of issues that I want to highlight:

  • Thawing of the perennially frozen peat changes the carbon fluxes of palsa mires as carbon previously trapped by permafrost becomes available for decay. As the area of dry peat surface decreases, more carbon is released into the atmosphere in the form of more effective greenhouse gas methane (CH4) instead of carbon dioxide (CO2). Recently, also the effects of permafrost thaw on the emissions of nitrous oxide (N2O), which is a strong greenhouse gas, have gained more attention (Marushchak et al, 2011).

  • The heterogeneity formed by variety of mire surfaces, thermokartst ponds and dry palsa mounds creates favorable conditions for species richness in these subarctic environments. In particular, the number and density of bird species seems to be high in the zone of palsa mires compared to more southern mire zones in Fennoscandia, even though no species have been reported to be exclusive to palsa mires (Luoto et al, 2004). This relationship, as well as overall significance of palsa mires for biodiversity is still poorly understood, however.

References

 

Edited by Clara Burgard


Mariana Verdonen is an Early Stage Researcher at the University of Eastern Finland. She focuses on optical, multi-temporal and multiscale remote sensing of environmental changes in Arctic and Subarctic areas. Mariana’s scientific interests are generally in geomorphology, permafrost-landscape dynamics and remote sensing of the Cryosphere. She tweets as @MarianaVerdonen. Contact Email: mariana.verdonen@uef.fi