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Background: Northern Finland, like the rest of the Arctic, has experienced increases in mean annual temperature, the number of winter rains, the number of thaw–freeze days, the number of extremely warm weather events, and a shortened snow season. These changes have produced numerous problems for reindeer herders whose livelihoods rely on a healthy ecosystem with predictable weather patterns. Methods: We performed a scoping literature review to assess how climate change induced extreme weather has negatively impacted reindeer herding as well as the health and wellbeing of reindeer herders. Results: Late snow cover negatively impacts reindeer herding through a more widely dispersed herd that increases the work to gather reindeer, leads to reduced calf weight, and results in less meat for sale. This increased labor, especially in extreme cold conditions, can also negatively impact reindeer herder health. Icing due to thaw–freeze and rain‐on‐snow events makes it impossible for reindeer to dig through the snow to access lichens, increasing the need for reindeer herders to keep the herd in winter enclosures and provide supplemental feed. Conclusion: Climate change induced weather events such as late snow cover and icing increase reindeer herder efforts and expenses, put their livelihood at risk, and put their health at risk. [ABSTRACT FROM AUTHOR]

Objective: High levels of total energy expenditure (TEE, kcal/day) have been documented among numerous human populations such as tropical climate horticulturalists and high‐altitude agriculturalists. However, less work has been conducted among highly physically active cold climate populations. Methods: In October 2018, TEE was measured using the doubly labeled water (TEEDLW, N = 10) and flex‐heart rate methods (TEEHR, N = 24) for 6–14 days among reindeer herders (20–62 years) in northern Finland during an especially physically demanding, but not seasonally representative, period of the year for herders—the annual reindeer herd roundup. Self‐reported dietary intake was also collected during TEE measurement periods. TEE was then compared to that of hunter gatherer, farming, and market economies. Results: During the herd roundup, herders expended a mean of 4183 ± 949 kcal/day as measured by the DLW method, which was not significantly different from TEEHR. Mean caloric intake was 1718 ± 709 kcal/day, and was significantly lower than TEEDLW and TEEHR (p <.001). Herder TEEDLW was significantly higher than that of hunter gatherer (p =.0014) and market (p <.0014) economy populations; however, herder TEEDLW was not different from that of farming populations (p =.91). Conclusion: High TEE and low caloric intake among herders reflect the extreme demands placed on herders during the annual herd round up. Although TEEDLW was similar between cold climate herders and hot climate farming populations, there are likely differences in how that TEE is comprised, reflecting the local ecologies of these populations. [ABSTRACT FROM AUTHOR]

Objective: Elevated resting metabolic rates (RMR, kcal/day) are a well‐established mechanism for maintaining core body temperature among cold climate populations. A high degree of interindividual variation has recently been noted among circumpolar populations. To further examine RMR variability, we investigated anthropometric and metabolic differences among reindeer herders from subarctic Finland. Methods: Resting metabolic rates, body mass, body composition, height, age, and sex were measured among 20 reindeer herders (5 females, 15 males, 20‐64 years) from seven herding districts surrounding the Arctic Circle of Finland in January of 2019. Results: Females had a mean RMR of 1798 ± 216 kcal/day and males 1753 ± 503 kcal/day. When controlling for body mass and fat‐free mass, females had significantly higher RMRs relative to males (P <.01). Contrary to previous cold climate population studies, measured RMR among males was not significantly different from predictive equation estimates (P >.05). However, predictive equations significantly underestimated female RMR by a mean of 25.2% ± 5.9% (P <.01). Conclusion: These results mirror earlier findings, though in ways previously unseen. In this population: (a) There is a high degree of RMR interindividual variability, but only among males, and (b) there is evidence for elevated RMR, but only among females. Though the sample size is small, preliminary results suggest the presence of sex‐based differences in metabolic adaptations to cold climates within this population subset. Potential reasons for this sex‐based difference are discussed including a presentation of a hypothesis about the dual role of thyroid hormone in both reproductive and metabolic processes. [ABSTRACT FROM AUTHOR]

We examined the effects of undernutrition on lipid metabolism in reindeer (<1 year) during mid-winter and spring, with particular focus on the proportions of polyunsaturated fatty acids (PUFAs) in major serum lipids. The reindeer (n=8) were fed their winter feed, lichen, ad libitum for 5 weeks, followed by 40% restriction of energy for 8 weeks and refeeding to normal for 6 weeks. The concentrations of major serum lipids, cholesterol and phospholipids decreased significantly during the ad libitum period (by 50 and 44%, respectively). The proportion of major PUFA, linoleic acid in serum cholesteryl esters, decreased from 48.2 to 38.4% during the ad libitum period (P < 0.01), and to 29.2% during the restriction period (P < 0.001). The proportion of linoleic acid in phospholipids decreased from 27.9 to 15.6% during the ad libitum period (P < 0.001), and to 13.0% during the restriction (P < 0.01). Also α-linolenic acid in the major lipids decreased significantly during the ad libitum and restriction periods. The decreases in the major lipids and linoleic acid were reversed during the refeeding. The control group (n=8) which was fed high-quality concentrates ad libitum gained weight most of the spring but showed similar although slower decreases in the major serum lipids and PUFAs than the lichen group. Our results indicate that feeding reindeer on lichen during winter leads to the retardation of growth and reductions in major serum lipids and their principal C18-PUFA proportions. The decreased proportions of the principal PUFAs most probably reflect their low dietary intake but may have been modified also by seasonal factors. [ABSTRACT FROM AUTHOR]