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Case 4: Sweden 2 - Temperature extremes

The following is a preliminary assessment of how Sámi communities in Sweden will be affected by climate change – the main hazard in focus, in this case, is extreme temperatures.

The assessment will be developed further as the project progresses.

Billede af Joe Green

Sámi pastoralism

Sámi pastoralism, or reindeer husbandry, is practiced across Sápmi, the territory of the indigenous Sámi people which spans across four nation-states – Norway, Sweden, Finland, and Russia. The exact form of Sámi pastoralism differs across Sápmi, but in Swedish, Sápmi is based on natural grazing and historical migration patterns across eight seasons and practiced within reindeer herding communities.

Pastoralism at its very core depends on the existence of multi-purpose and continuous landscapes that allow for mobility and flexibility that can adapt to fluctuating climatic and environmental conditions (Scoones, 2020). How pastoralists navigate this natural variability in their everyday lives as herders is an incredibly impressive feature of pastoralism as a livelihood and cultural practice. As pasture availability for each season is largely determined by uncertain and dynamic climatic and environmental factors, the pastoral ecology of Sámi pastoralism is within the scientific field of ecology best understood with so-called “non-equilibrium models”, captured in the metaphor nature in flux (Benjaminsen et al., 2015; Reinert & Benjaminsen, 2015). In essence, whether or not food is available to reindeer during critical survival periods depends on event-driven weather dynamics with short periods, such as factors that create different snow and ice conditions, a specific example of which we approach in this case study.

Winter seasons represent a critical period for the Sámi pastoral ecology as this is when the availability of ground lichens and pendulous lichens, as seasonal food resources of utmost importance, are crucial for reindeer survival (Heggberget et al., 2002). Our research represents a collaboration with the Maskaure reindeer herding community located in Arjeplog municipality, as well as in Norsjö and Skellefteå municipalities (Figure 1), where our aim as researchers is to help build capacity to deal with extensive basal ice formation events, briefly introduced and justified below.

Figure 1.jpg
Billede af T Fe

Figure 1 The location of the case communities

Basal ice formation

What is basal ice formation and why is it important to study? Basal ice formation refers to an ice layer thick enough to encapsulate lichen and plants at the bottom vegetation layer (Figure 2). Basal ice formation makes ground lichens inaccessible for reindeer throughout winter, at times it can even rot the lichens. This phenomenon thus makes ground lichen inaccessible for reindeer, and only the arrival of spring can alter this state. This is why basal ice formation represents the worst possible snow and ice condition for winter pasturelands (although only one out of many different kinds of snow and ice conditions), as the reindeer cannot access its main source of food which comes with significant costs and burdens for reindeer herding communities (Ryd, 2020; see also Riseth et al., 2011). Thus, basal ice formation of this kind, called botneskárta or čuohki in Northern Sámi language, has traditionally been considered an extreme weather event by Sámi reindeer herders in terms of its impact.

What causes basal ice formation? For basal ice to form sufficient water amounts, the water must be delivered onto a cold substrate on which it remains long enough during cold temperatures to freeze. For basal ice to remain over winter as čuohki it has to be covered by snow before it has a chance to melt and dry. Two types of weather events during the first durable snow cover period can create conditions for čuohki to occur: rain-on-snow events, and thaw-and-freeze events. The temporal scales of these events are short and can come as extremes, but their impact has a longer duration.

The mechanisms above must be followed by temperatures below 0°C and precipitation that causes a snow cover before the basal ice can disappear. As such, the spatial variability of basal ice formation is high as ice and snow parameters are subject to many climatic and environmental factors (Bokhorst et al., 2016). Thus, botneskárta or čuohki as it is called in the Northern Sámi language is a complex hazard that changes the status of winter pastures and while it is related to rain-on-snow and/or thaw-and-refreeze events it is not reducible to them. Temperature and precipitation patterns are nevertheless key abiotic factors, that much is clear.

Figure 2.jpg

Figure 2 Illustration of basal ice formation (David Harnesk)


The case is surrounded by important non-climatic factors as well. As mentioned, basal ice formation impacts Sámi pastoralism negatively as it blocks or even rots ground lichens. This is even more problematic at this point in time as there has been a massive decline in ground lichens and pendulous lichens since the 1950s due to forestry practices (Horstkotte & Moen, 2019; Horstkotte et al., 2011; Sandström et al., 2016). With already less food during winter, extensive basal ice formation events force Sámi pastoralists to either migrate to old-growth forests with pendulous lichens (which have decreased significantly) or use supplementary feeding, which Sámi pastoralists do not view as a long-term solution. Thus, it is important to look into the state of the forest ecosystem as well.

From a natural scientific perspective, we are currently investigating questions such as:

  • What are relevant causal factors that lead to basal ice formation events having an impact on Sámi pastoralism?

  • How might climate change have contributed to those causal factors?

  • How might climate change make such an event even more severe in the future?

From a social scientific perspective, we combine these biophysical insights with analysis of the social-historical context, place attachment, and narratives to better achieve more contextually relevant advice on pathways forward. Specifically, our project is designed to support reindeer herding communities’ to articulate stronger claims surrounding the environmental and climatic conditions that shape their livelihoods when interacting with authorities and civil society organizations.

Follow our research here on this website and by following case study leader David Harnesk on Twitter.

Åbn bøger


  • Benjaminsen, T. A., Reinert, H., Sjaastad, E., & Sara, M. N. (2015). Misreading the Arctic landscape: A political ecology of reindeer, carrying capacities, and overstocking in Finnmark, Norway. Norsk Geografisk Tidsskrift - Norwegian Journal of Geography, 69(4), 219–229.

  • Bokhorst, S., Pedersen, S. H., Brucker, L., Anisimov, O., Bjerke, J. W., Brown, R. D., Ehrich, D., Essery, R. L. H., Heilig, A., Ingvander, S., Johansson, C., Johansson, M., Jónsdóttir, I. S., Inga, N., Luojus, K., Macelloni, G., Mariash, H., McLennan, D., Rosqvist, G. N., … Callaghan, T. V. (2016). Changing Arctic snow cover: A review of recent developments and assessment of future needs for observations, modelling, and impacts. In Ambio (Vol. 45, Issue 5, pp. 516–537). Springer Netherlands.

  • Heggberget, T. M., Gaare, E., & Ball, J. P. (2002). Reindeer (Rangifer tarandus) and climate change: Importance of winter forage. Rangifer, 22(1), 13.

  • Horstkotte, T., & Moen, J. (2019). Successional pathways of terrestrial lichens in changing Swedish boreal forests. Forest Ecology and Management, 453, 117572.

  • Horstkotte, T., Moen, J., Lämås, T., & Helle, T. (2011). The Legacy of Logging—Estimating Arboreal Lichen Occurrence in a Boreal Multiple-Use Landscape on a Two Century Scale. PLoS ONE, 6(12), e28779.

  • Reinert, H., & Benjaminsen, T. A. (2015). Conceptualising resilience in Norwegian Sámi reindeer pastoralism. Resilience, 3(2), 95–112.

  • Riseth, J. Å., Tømmervik, H., Helander-Renvall, E., Labba, N., Johansson, C., Malnes, E., Bjerke, J. W., Jonsson, C., Pohjola, V., Sarri, L. E., Schanche, A., & Callaghan, T. V. (2011). Sámi traditional ecological knowledge as a guide to science: Snow, ice and reindeer pasture facing climate change. Polar Record, 47(3), 202–217.

  • Ryd, Y. (2020). Snö – Renskötaren Johan Rassa berättar. Ord & visor förlag, Skellefteå, Sweden.

  • Sandström, P., Cory, N., Svensson, J., Hedenås, H., Jougda, L., & Borchert, N. (2016). On the decline of ground lichen forests in the Swedish boreal landscape: Implications for reindeer husbandry and sustainable forest management. Ambio, 45(4), 415–429.

  • Scoones, I. (2020). Pastoralists and peasants: perspectives on agrarian change. Journal of Peasant Studies.

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