One predicted consequence of global warming is an increased frequency of extreme weather events, such as heat waves, droughts, or heavy rainfalls. In parts of the Arctic, extreme warm spells and heavy rain-on-snow (ROS) events in winter are already more frequent. How these weather events impact snow-pack and permafrost characteristics is rarely documented empirically, and the implications for wildlife and society are hence far from understood. Here we characterize and document the effects of an extreme warm spell and ROS event that occurred in High Arctic Svalbard in January-February 2012, during the polar night. In this normally cold semi-desert environment, we recorded above-zero temperatures (up to 7°C) across the entire archipelago and record-breaking precipitation, with up to 98 mm rainfall in one day (return period of >500 years prior to this event) and 272 mm over the two-week long warm spell. These precipitation amounts are equivalent to 25 and 70% respectively of the mean annual total precipitation. The extreme event caused significant increase in permafrost temperatures down to at least 5 m depth, induced slush avalanches with resultant damage to infrastructure, and left a significant ground-ice cover (∼5-20 cm thick basal ice). The ground-ice not only affected inhabitants by closing roads and airports as well as reducing mobility and thereby tourism income, but it also led to high starvation-induced mortality in all monitored populations of the wild reindeer by blocking access to the winter food source. Based on empirical-statistical downscaling of global climate models run under the moderate RCP4.5 emission scenario, we predict strong future warming with average mid-winter temperatures even approaching 0°C, suggesting increased frequency of ROS. This will have far-reaching implications for Arctic ecosystems and societies through the changes in snow-pack and permafrost properties.

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/npsi/ctrl?lang=en http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/ctrl?lang=fr Access and use of this website and the material on it are subject to the Terms and Conditions set forth at http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/jsp/nparc_cp.jsp?lang=en NRC Publications Archive Archives des publications du CNRCThis publication could be one of several versions: author's original, accepted manuscript or the publisher's version. / La version de cette publication peut être l'une des suivantes : la version prépublication de l'auteur, la version acceptée du manuscrit ou la version de l'éditeur. Geotechnical Journal, 21, 2, pp. 250-258, 1984-05 Measurements of snow creep pressures from the centre section of a 3.4 m high and 15 m long avalanche-defence supporting structure located on a mountain in western Norway are presented. The site has a deep snow cover and an average slope angle of 25". The measurement configuration corresponds to plane-strain conditions and the data, along with measured snowpack parameters, allow comparison with simple theoretical predictions. The analysis shows that the average pressure on the structure I may be calculated fairly accurately using linear, viscous modelling for the snow deformation. The maximum pressures proved to be higher than that provided by a linear model and this is considered characteristic of nonlinear material. The implications of these results for estimates of design loads are discussed. CanadianKeywords: snow pressure, creep, measurements, viscous, plane-strain, finite element. 9L'article prksente des mesures de pression de fluage de la neige sur la section centrale d'une structure de protection contre les avalanches de 3,4 m de haut et 15 m de long, situCe sur une montagne dans l'ouest de la Norvkge. Le site prksente un couvert de neige Cpais et une pente moyenne de 25". La configuration de l'installation de mesure correspond i des conditions de dCformation plane et les dondes, assocites aux paramttres mesures du couvert de neige, permettent une comparaison avec des prkdictions thCoriques simples. L'analyse montre que la pression moyenne sur la structure peut &tre calculCe avec une prkcision acceptable au moyen d'un modtle visqueux linCaire des dCformations de la neige. Les pressions maximum se sont avtrCes plus fortes que celles dCduites d'un modkle linkaire, ce qui est considCrC typique d'un matCriau non-1inCaire. Les implications de ces rksultats sur I'Cvaluation des charges de calcul sont discutCes.Mots-clPs: pression de neige, fluage, mesure, viscositC, dCformation plane, ClCments finis.[Traduit par la revue]Can. Geotech. 1. 21, 250-258 (1984) Introduction compare the field measurements with these models. This An important engineering problem concerning the comparison has two important motivating aspects: (1) design of structures on mountains with deep snow cover by comparing actual measurements with a linear, viscous is the calculation of expected pressures due to intemp-deformation model, those features of the problem that tion of snow creep (internal defo...

/npsi/ctrl?lang=en http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/ctrl?lang=fr Access and use of this website and the material on it are subject to the Terms and Conditions set forth at http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/jsp/nparc_cp.jsp?lang=en NRC Publications Archive Archives des publications du CNRCThis publication could be one of several versions: author's original, accepted manuscript or the publisher's version. / La version de cette publication peut être l'une des suivantes : la version prépublication de l'auteur, la version acceptée du manuscrit ou la version de l'éditeur. Science and Technology, 17, 1, pp. 33-47, 1989-09-01 Cold Regions