CR
Cryospheric Sciences

permafrost

Image of the Week – Heat waves during Polar Night!

Fig. 1: (Left) Evolution of 2-m air temperatures from a reanalysis over December 2016. (Right) Time series of temperature at the location of the black cross (Svalbard). Also shown is the 1979-2000 average and one standard deviation (blue). [Credit: François Massonnet ; Data : ERA-Interim]

The winter 2016-2017 has been one of the hottest on record in the Arctic. In our Image of the Week, you can see that air temperatures were positive in the middle of the winter! Let’s talk about the reasons and implications of this warm Arctic winter. But first, let’s take a tour in Svalbard, the gateway to the Arctic…

A breach in the one of the world’s largest seed vaults

The Global Seed Vault on Svalbard (located at the black cross in our Image of the Week) is one of the world’s largest seed banks. Should mankind face a cataclysm, 800,000 copies of about 4,000 species of crops can safely be recovered from the vault. Buried under 120 m of sandstone, located 130 m above sea level, and embedded inside a thick layer of permafrost, the vault can withstand virtually all types of catastrophe – natural or man-made. This means, for example, that it is high enough to stay above sea level in case of a large sea-level rise, or that it is far enough from regions that might be affected by nuclear warfare. But is it really that safe? Last winter, vault managers reported water flooding at the entrance of the cave, after an unexpected event of permafrost melt in the middle of polar night. Not enough to put the seeds at risk (they are safely guarded in individual chambers deeper in the mountainside), but worrying enough to raise concern about how, and why such an event happened…

Fig. 2: Entrance of the Svalbard Global Seed Vault. [Credit: Dag Terje Filip Endresen, Wikimedia Commons ].

Soaring temperatures in the Arctic

The Arctic region is often dubbed the “canary in the coal mine” for climate change: near-surface temperatures there have risen at twice the pace of the world’s average, mainly due to the process of “Arctic Amplification whereby positive feedbacks enhance greatly an initial temperature perturbation. Increases in lower-troposphere Arctic air temperatures have occurred in conjunction with a dramatic retreat and thinning of the sea-ice cover in all seasons, a decrease of continental spring snow cover extent, and significant mass loss from glaciers and ice sheets (IPCC, 2013)

Winter temperatures above freezing point

The last two winters (2015-2016 and 2016-2017) have been particularly exceptional. As displayed in our Image of the Week for winter 2016-2017 and here for 2015-2016 (see also two news articles here and here for an accessible description of the event), temporary intrusions of relatively warm air pushed air temperatures above freezing point in several parts of the Arctic, even causing sea ice to “pause” its expansion at a period of the year where it usually grows at its fastest rate (see Fig. 3).

Fig.3 : Mean Arctic sea ice extent for 1981 to 2010 (grey), and the annual cycles of 1990 (blue), and 2016-2017 (red and cyan, respectively). [Credit: National Snow and Ice Data Center. Interactive plotting is available here ]

Cullather et al. (2016) and Overland and Wang (2016) conducted a retrospective analysis of the 2015-2016 extreme winter and underlined that the mid-latitude atmospheric circulation played a significant role in shaping the observed temperature anomaly for that winter (see also this previous post). Scientists are still working to analyse the most recent winter temperature anomaly (2016 – 2017).

Unusual?

How unusual are such high temperatures in the middle of the boreal winter? It is important to keep in mind that the type of event featured in our Image of the Week results from the superposition of weather and climate variability at various time scales, which must be properly distinguished. At the synoptic scale (i.e., that of weather systems, several days), the event is not exceptional. For example, a similar event was already reported back in 1975! It is not surprising to see low-pressure systems penetrate high up to the Arctic.

At longer time scales (several months), the observed temperature anomaly in the recent two winters is more puzzling. The winter 2015-2016 configuration appears to be connected with changes in the large-scale atmospheric circulation (Overland and Wang, 2016). To understand the large-scale atmospheric circulation, scientists like to map the so-called “geopotential heightfield for a given isobar, that is, the height above sea level of all points with a given atmospheric pressure. The geopotential height is a handy diagnostic because, in a first approximation, it is in close relationship with the wind: the higher the gradient in geopotential height between two regions, the higher the wind speed at the front between these two regions. The map of geopotential height anomalies (i.e., deviations from the mean) for the 700 hPa level in December (Fig. 4) is suggestive of the important role played by the large-scale atmospheric circulation on local conditions. The link between recent Arctic warming and mid-latitude atmospheric circulation changes is a topic of intense research.

Fig.4: Anomaly in 700 hPa geopotential height, December 2016 (with regard to the reference period 1979-2000) [Credit: François Massonnet; Data: ERA-Interim]

Finally, at climate time scales (several years to several decades), this event is not so surprising: the Arctic environment has changed dramatically in the last few decades, in great part due to anthropogenic greenhouse gas emissions. With a warmer background state, there is higher probability of winter air temperatures surpassing 0°C if synoptic and large-scale variability positively interact with each other, as seems to have been the case during the last two winters.

What does this mean for future winters?

The rapid transformation of the Arctic is already having profound implications on ecosystems (Descamps et al., 2016) and indigenous populations (e.g., SWIPA report). To a larger extent, it can potentially affect our own weather: we polar scientists like to say that “what happens in the Arctic, does not stay in the Arctic”. The unusual summers and winters that large parts of Europe, the U.S. and Asia have experienced in recent years might be related to the rapid Arctic changes, according to several scientists – but there is no consensus yet on that matter. One thing is known for sure: the last two winters have been the warmest on record, but this might just be the beginning of a long chain of more extreme events…

Further reading

Edited by Scott Watson and Clara Burgard


François Massonnet is a F.R.S.-FNRS Post-Doctoral Researcher at the Université catholique de Louvain and affiliated at the Barcelona Supercomputing Center (Spain). He is assessing climate models as tools to understand (retrospectively and prospectively) polar climate variability and beyond. He tweets as @FMassonnet. Contact Email: francois.massonnet@uclouvain.be

Image of the Week – When the dirty cryosphere destabilizes!

Image of the Week – When the dirty cryosphere destabilizes!

Ice is usually something you see covering large ocean areas, mountain tops and passes or as huge sheets in polar regions. This type of ice is clearly visible from space or with the naked eye. There is, however, a large volume of ice that is less visible. This ice is distributed over the polar and high alpine permafrost regions; and is the ice hidden below ground. It might be hidden, but that doesn’t mean we should ignore it. If this below-ground ice melts, the ground might collapse!


On solid ground?

To change the surface of a landscape usually requires wind or water, which actively erodes the material around it. In permafrost areas, however, different mechanisms are at work. In these areas, the ground or parts of the ground, are frozen all year round and the formation and melting of below-ground ice changes the landscape in a complicated way. Below-ground ice can have many shapes and sizes depending on moisture availability, sediment type and thermal regime (French, 2007). Because a gram of ice has 9 % higher volume than a gram of water, simply freezing, thawing and re-freezing soil water can make the surface “wobbly” and irregular. Since ice doesn’t drain from a saturated soil, as water does, a permanently frozen soil can also contain moisture in excess of the absorption capacity of the soil – excess ice. This means that ice might take up the majority of the ground volume in ice-rich areas.

Our Image of the Week (Fig. 1) was taken in NE Greenland. The phenomenon shown is a result of ground, which has been frozen for many years, being destabilized. In this photo, the below-ground ice has begun to melt, and the decrease in ice volume has caused the ground to collapse, forming what is known as a thermokarst development (Fig. 1). This is just one type of feature that can be caused by below-ground ice mass loss. Kokelj and Jorgenson (2013) give a nice overview of recognized thermokarst features including: retrogressive thaw slumps, thermokarst lakes and active layer detachment slides. Ice melt might also simply be expressed as a lowering of the land surface (thermal subsidence), as observed in peat (Dyke and Slaten, 2010) and in areas with ice wedge polygons (Jorgenson et al., 2006), or in upraised plateaus (Chasmer et al., 2016).

the decrease in ice volume has caused the ground to collapse

The spatial scales of these types of collapse features span from depressions of 10 cm depth to areas of several square kilometers, with thermokarst features many meters deep. The rates of surface change also vary from sudden detachment and slide of the unfrozen upper active layer on slope, to features developed over centuries and even millennia (e.g. Morgenstern et al., 2013).

The most dramatic surface changes often happen where ground ice content is high, such as in the coastal lowland tundras of Siberia (e.g. Morgenstern et al., 2013) or coastal northern Canada (Fortier, et L., 2007). However, thermokarst development is found also in coastal Greenland (Fig. 1) and even the McMurdo Dry Valleys of Antarctica (Levy et al., 2013).

Why does the ground ice melt?

Many factors can lead to the destabilization of below-ground ice bodies. Notable ones are:

  • Erosion of the surface allows for atmospheric energy to penetrate deeper into the ground.
  • Thermal contraction or other types of cracks might create an easy access to deeper layers for water and energy.
  • Persistent running water might erode physically as well as transfer fresh energy into the system.

Fig. 2 shows a recently opened crack in the ground, close to the karst formation shown in Fig.1. The crack reveals a large body of massive (pure ice) below-ground ice. The opening of the crack, however, also creates a highway for heat energy into the now unstable ice body, which will start degrading.

Figure 2: Looking into a recently opened crack revealing a large ice body just below the summer thaw layer, NE Greenland [Credit: Laura Helene Rasmussen]

“And so what?”

The surface changes somewhat. No big deal. Why investigate where and how and how much and how fast?

For people living in permafrost areas thermal subsidence might happen below the foundation of their house or destabilize the one road leading to their local airport (Fortier, et al., 2011).

Figure 3: Taking a closer (!) look at below-ground ice, NE Greenland [Credit: Line Vinther Nielsen].

Thermal subsidence might also change the hydrology of the area, causing surface water to find new routes (Fortier, et al., 2007) or pool in new places. When water pools in the depressions above frozen ground, the exchange of energy between the atmosphere and the permafrost is altered.

There is increased heat transport downward into the ground in summer (Boike et al., 2015), which can then lead to more melting. Similarly, thermokarst development itself exposes more frozen ground to above-zero temperatures, leading to further thawing (Chasmer et al., 2016)

and crucially mobilising otherwise dormant carbon stored in the permafrost (Tarnocai, et al., 2009).

Reports of an increase in rates of thaw have been linked to recent climatic warming (Kokelj and Jorgenson, 2013), and changes in precipitation patterns (e.g. Kokelj et al., 2015). So expect to see this “dirty“ cryospheric component receiving more attention, and don’t be surprised if you see an increasing number of strange scientists figuratively or literally (!) sticking their heads into cracks in the ground…

Edited by Emma Smith and Clara Burgard


Laura Helene Rasmussen is a Danish permafrost scientist working at the Center for Permafrost, University of Copenhagen. She has spent many seasons in Greenland, working with the Greenland Ecosystem Monitoring Programme and is interested in Arctic soils as an ecosystem component, their climate sensitivity, functioning and simply understanding what goes on below.

Image of the Week – Climate Change and the Cryosphere

Image of the Week – Climate Change and the Cryosphere

While the first week of COP22 – the climate talks in Marrakech – is coming to an end, the recent election of Donald Trump as the next President of the United States casts doubt over the fate of the Paris Agreement and more generally the global fight against climate change.

In this new political context, we must not forget about the scientific evidence of climate change! Our figure of the week, today summarises how climate change affects the cryosphere, as exposed in the latest assessment report of the Intergovernmental Panel on Climate Change (IPCC, 2013, chapter 4)


Observed changes in the cryosphere

Glaciers (excluding Greenland and Antarctica)

  • Glaciers are the component of the cryosphere that currently contributes the most to sea-level rise.
  • Their sea-level contribution has increased since the 1960s. Glaciers around the world contributed to the sea-level rise from 0.76 mm/yr (during the 1993-2009 period) to 0.83 mm/yr (over the 2005-2009 period)

Sea Ice in the Arctic

  • sea-ice extent is declining, with a rate of 3.8% /decade (over the 1979-2012 period)
  • The extent of thick multiyear ice is shrinking faster, with a rate of 13.5%/decade (over the 1979-2012 period)
  • Sea-ice decline sea ice is stronger in summer and autumn
  • On average, sea ice thinned by 1.3 – 2.3 m between 1980 and 2008.

Ice Shelves and ice tongues

  • Ice shelves of the Antarctic Peninsula have continuously retreated and collapsed
  • Some ice tongue and ice shelves are progressively thinning in Antarctica and Greenland.

Ice Sheets

  • The Greenland and Antarctic ice sheets have lost mass and contributed to sea-level rise over the last 20 years
  • Ice loss of major outlet glaciers in Antarctica and Greenland has accelerated, since the 1990s

Permafrost/Frozen Ground

  • Since the early 1980s, permafrost has warmed by up to 2ºC and the active layer – the top layer that thaw in summer and freezes in winter – has thickened by up to 90 cm.
  • Since mid 1970s, the southern limit of permafrost (in the Northern Hemisphere) has been moving north.
  • Since 1930s, the thickness of the seasonal frozen ground has decreased by 32 cm.

Snow cover

  • Snow cover declined between 1967 and 2012 (according to satellite data)
  • Largest decreases in June (53%).

Lake and river ice

  • The freezing duration has shorten : lake and river freeze up later in autumn and ice breaks up sooner in spring
  • delays in autumn freeze-up occur more slowly than advances in spring break-up, though both phenomenons have accelerated in the Northern Hemisphere

Further reading

How much can President Trump impact climate change?

What Trump can—and can’t—do all by himself on climate | Science

US election: Climate scientists react to Donald Trump’s victory  | Carbon Brief

Which Trump will govern, the showman or the negotiator? | Climate Home

GeoPolicy: What will a Trump presidency mean for climate change? | Geolog

Previous posts about IPCC reports

Image of the Week — Ice Sheets and Sea Level Rise

Image of the Week —  Changes in Snow Cover

Image of the Week — Atmospheric CO2 from ice cores

Image of the Week — Ice Sheets in the Climate

Edited by Emma Smith

Image of The Week – Prize Polar Pictures!

Image of The Week –  Prize Polar Pictures!

Last week was the Fall APECS International Polar Week, designed to promote and celebrate the great collaborative science that goes on around the world to further our understanding of the polar regions. Part of this celebration was a figure competition, to find the most “eye-catching, informative and inspiring” figures that illustrate aspects of polar science.

What better, we thought, than to feature the winning figure as our Image of The Week? They say a image tells a thousand words and here at the EGU Cryosphere blog we wholeheartedly agree!


APECS International Polar Week

For the past 4 years APECS (The Association of Polar Early Career Scientists) have organised an International Polar Week each March and September. The International Polar Weeks are timed to coincide with the two equinoxes – the only times of year where the Northern and Southern hemisphere are equally illuminated by the sun – a rather nice way to tie our polar regions together!

International Polar Week highlights the importance of the polar regions and, in particular, provides an opportunity to develop new outreach activities in collaboration with teachers and educators. APECS have a fantastic catalogue of polar outreach resources for anyone wanting to spread the word about these diverse and important regions of Earth. They also organise events such as polar film festivals, talks and a figure competition. Today’s Image of The Week is the winning figure from the Polar Week figure competition, created by Noémie Ross as part of the A Frozen-Ground Cartoon outreach project.

A Frozen-Ground Cartoon”  – Where science meets art!

Thawing permafrost in Siberia [Credit: Guido Grosse via imaggeo ]

“A Frozen-Ground Cartoon outreach project was designed to help spread the word about permafrost and its crucial importance in our changing climate through thematic comic strips. Through these cartoons and comics the project aims to make permafrost science accessible to children, young people and the parents and teachers.

The project is funded by the International Permafrost Association and chaired by Frédéric Bouchard with a core group of young researchers from Canada, Germany, Sweden and Portugal providing the scientific information. The cartoons, one of which we feature today, are all designed by young artists.

Today’s image of the week highlights some of the ways that thawing permafrost will affect the lives of indigenous peoples in the Urals who live by reindeer-herding. This cartoon was based on the study of Istomin and Habeck (2016), and effectively provides an accessible way to communicate the key findings of this study to a general audience.

 

Edited by Sophie Berger

 


“A Frozen-Ground Cartoon” Team:

Project Leader: Frédéric Bouchard
Collaborators: Bethany Deshpande, Michael Fritz, Julie Malenfant-Lepage, Alexandre Nieuwendam, Michel Paquette, Ashley Rudy, Matthias B. Siewert, Ylva Sjöberg, Audrey Veillette, Stefanie Weege, Jon Harbor


Image of The Week – Tumbling Rocks

Image of The Week – Tumbling Rocks

This photo captures a rockfall at the summit of Tour de Ronde, 3792 m above sea level in the Mont Blanc Massif. On 27 August 2015, around 15000 m3  of rock fell from the steep walls of the mountain.

Why do mountains crumble ?

Rockfalls such as the one on the photo have been linked to thawing permafrost. The exact mechanism that leads to these events is not fully understood, however, it is thought that areas of the mountain becoming destabilised during thaw periods (Luethi et al, 2015). Records show that during heat waves — as for instance the one that happened in the summer of 2015 in the Mont Blanc Massif — there are many more rockfalls than during colder years. Researchers at the Université Savoie Mont Blanc have been monitoring this area of the Alps for many years, installing a network of temperature sensors on the surface and in boreholes drilled into the rock to try and better understand the link between temperature and rock slope stability (see Magnin et al, 2015).

What can we do about it? 

The short answer is that there is not a lot that can be done to prevent it. However, long term monitoring studies, such as the one from Magnin et al (2015), help to better understand what conditions are likely to result in rockfall activity and therefore predict when they are likely to happen. By doing this in the Mont Blanc region the team from Université-Savoie Mont Blanc has been able to put in place an alert network to warn the local community to increased rockfall activity. This means that the potential damage can be minimised, for example, by closing climbing routes in risky areas.


Further reading

Check out our blog post about how cryospheric research can transform lives.

  • Magnin, F., Deline, P., Ravanel, L., Noetzli, J., and Pogliotti, P. (2015) : Thermal characteristics of permafrost in the steep alpine rock walls of the Aiguille du Midi (Mont Blanc Massif, 3842 m a.s.l), The Cryosphere, 9, 109-121, doi:10.5194/tc-9-109-2015
  • Luethi, R., Gruber, S. and Ravanel, L., (2015) Modelling transient ground surface temperatures of past rockfall events: towards a better understanding of failure mechanisms in changing periglacial environments. Geografiska Annaler: Series A, Physical Geography, 97, 753767. doi: 10.1111/geoa.12114

Edited by Emma Smith and Sophie Berger

When Cryospheric Research Transforms Lives

When Cryospheric Research Transforms Lives

My name is Kathi Unglert, and I’m reporting from the EGU 2016 General Assembly as part of the EGU student reporter programme. Below is my second contribution to the Cryosphere Blog – this time about how cryosphere research can have a real impact on people’s lives.

Antoni Lewkowicz – he’s famous, according to a comment I overheard in Tuesday’s PICO session on applied geophysics in cryosphere research. I’m a volcanologist, so I guess I wouldn’t know. But what I do know is that he’s a passionate scientist. His PICO presentation got my curiosity, but what really grabbed my attention is a small statement he made during the subsequent discussion of his PICO poster. But I’m getting ahead of myself.

One thing I’ve learned over the last few days is that cryospheric research can have a big impact on people’s lives. Antoni’s work is part of a project on the effects of a changing environment in Northern Canada, and on adaptation to climate change. The Yukon is Canada’s northwestern most territory, right on the border to Alaska. It’s about twice the size of the UK, but with just under 40,000 people its population is lower than 0.1% of the UK’s population. You can imagine the vast wilderness in the Yukon. Yet, for the people living in this part of the world, climate change is happening right now. Permafrost is disappearing (see the blog Image of The Week from last Friday), and the thawed ground is the foundation of now wonky houses. Among others, the Kluane First Nation and their territory are threatened by the disappearance of frozen ground. They have teamed up with various universities and research institutes for Antoni’s climate change adaption and hazard mapping project to identify regions where future construction is less likely to be affected by thawing permafrost. The project reveals that on previously burnt ground, where the permafrost has already thawed, the shallow ground is less likely to move and settle any further, so it’s safer for buildings.

An old building in Dawson, Yukon, warped by thawing permafrost. Photo credit: Antoni Lewkowicz

An old building in Dawson, Yukon, warped by thawing permafrost. Photo credit: Antoni Lewkowicz

Ludovic Ravanel also studies permafrost. The researcher and mountain guide has set up a network of observers – fellow guides, hut keepers, cable car operators and more – to monitor rockfalls at Aiguille du Midi, a peak at over 3,800 m altitude in the Mont Blanc Massif in France. Even a small chunk of rock that tumbles down the steep slopes of the Massif can be fatal. Ludovic’s records show that during heat waves such as the one that happened in the summer of 2015, there are many more rockfalls than during colder years. During that year, at least one person lost their life because of crumbling parts of the mountain. On the poster in the permafrost open session on Wednesday, Ludovic and colleagues summarize the results from years of monitoring, and conclude that the rockfalls can clearly be attributed to thawing permafrost. This is bad news. The good news is that the observer network works well to alert the community of increased rockfall activity. Climbing routes can be closed, and protective measures can be introduced to keep falling rocks from getting to areas where people are, or from hitting important infrastructure.

Steep peak in the Mont Blanc Massif. Thawing permafrost can cause fatal rockfalls. Photo credit: Christian Massari (Imaggeo)

Steep peak in the Mont Blanc Massif. Thawing permafrost can cause fatal rockfalls. Photo credit: Christian Massari (Imaggeo)

The results from both studies are extremely important and have the potential to reduce costs to the community as well as transform and even save people’s lives. During Antoni’s presentation, the comment that led to this article was that the Kluane First Nation decided not to follow Antoni’s and his colleagues’ recommendation for where to build new homes. As Antoni says, people are people after all, and who wouldn’t like to build their house next to some nice trees, instead of burnt ground with some small shrubs. In contrast, Ludovic is happy with the actions taken at Aiguille du Midi following his research. However, in a comment concluding our conversation he admits that things might look different if he wasn’t local to Chamonix and if he wasn’t a mountain guide. In other words, his work has such a positive impact partly because he is very much part of the community and enjoys a level of trust that one might not be able to gain as an “outsider”.

Read more about the Yukon Hazard Mapping project in one of their reports here, or about the effect of thawing permafrost on the Mont Blanc Massif in this paper, published in The Cryosphere.

(Edited by Emma Smith)


profile_highres_EarthMatters_light

Kathi Unglert is a PhD student in volcanology at the University of British Columbia, Vancouver. Her work looks at volcanic tremor, a special type of earthquake that tends to happen just before or during volcanic eruptions. She uses pattern recognition algorithms to compare tremor from many volcanoes to identify systematic similarities or differences. This comparison may help to determine the mechanisms causing this type earthquake, and could contribute to improved eruption forecasting. You can find her on Twitter (@volcanokathi) or read her volcano blog.

Image of The Week – The Ice Your Eyes Can’t See!

Image of The Week – The Ice Your Eyes Can’t See!

Ice sheets and glaciers are very visible and much photographed (e.g. hereelements of the Cryosphere but what about the vast, invisible and buried parts?  Around a quarter of the land in the Northern hemisphere remains frozen year round, making up a hugely important part of the cryosphere known as permafrost. Permafrost largely exists at high latitudes (e.g. Siberia and the Canadian Arctic) and these areas store a huge amount of carbon, around twice as much as currently exists in the atmosphere. As the global climate warms these frozen areas of ground begin to thaw (Figure 2) and the trapped carbon is released into the atmosphere in the form of CO2 and methane – both greenhouse gases.

Figure 2: Permafrost thaw ponds in Hudson Bay Canada (taken from Wikimedia )

Figure 2: Permafrost thaw ponds in Hudson Bay Canada (taken from Wikimedia )

In order to better understand how and when this carbon will be released computer models known as land surface models (LSMs) are used. The estimates of carbon emissions produced by different LSMs vary greatly and many of the models are not yet able to accurately re-produce present day measured soil carbon levels well. A new study by Jafarov and Schaefer (2016), published last month in The Cryosphere, has improved the way frozen organic carbon is represented and simulated in the SiBCASA LSM, producing a simulated present-day soil carbon map (Figure 1) which is much closer to the known soil carbon map of the Northern Hemisphere (NCSCDv2). Both the spatial distribution of carbon and the total amount of simulated permafrost carbon (∼560 Gt C, much closer to the observed value ∼550 Gt C) is improved.

This is a step closer to better understanding permafrost carbon release and the factors that effect it. The authors of this study found they were able to make these improvement to the SiBCASA LSM by improving  simulated thermal dynamics of the soil, improving soil carbon dynamics and initializing the model using NCSCDv2 data.

To find out more check out the full article and remember, it’s not just the ice your eyes can see that is important!

Edited by Sophie Berger and Nanna Karlsson

 

 

 

 

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