Warmer and wetter winters: characteristics and implications of an extreme weather event in the High Arctic
Hansen, Brage Bremset; Isaksen, Ketil; Benestad, Rasmus E.; Kohler, Jack; Pedersen, Åshild Ø.; Loe, Leif Egil; Coulson, Stephen James; Larsen, Jan Otto; Varpe, Øystein
Journal article, Peer reviewed
Date
2014Metadata
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- Institutt for biologi [2671]
- Institutt for bygg- og miljøteknikk [5003]
- Publikasjoner fra CRIStin - NTNU [40041]
Abstract
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.