Present and future risk of winter weather to critical infrastructure Andrea Vajda, Ilari Lehtonen, Matti Kämäräinen Climate Service Centre Finnish Meteorological Institute EU FP7 project RAIN Workshop 17 Feb 2017, Helsinki This project has received funding from the European Union’s Seventh Framework Programme for research, technological development and demonstration under grant agreement no 608166. The contents of this presentation are the author's views. The European Union is not liable for any use that may be made of the information contained therein.

Outline Identification of severe winter phenomena and their impact European climatology of severe winter phenomena with focus on recent years Projected changes in the probability of winter hazards in the future climate until 2100 Summary

Severe winter phenomena Snowfall Snowstorm (blizzard) Cold spell Winter storm Snow load Freezing rain

Severe winter phenomena Impacts on critical infrastructure Heavy snowfall, blizzard, snow load and freezing rain can affect different type of CI Road infrastructure Blizzard, March 2013, Hungary Freezing rain, Feb 2014, Slovenia Heavy (coastal effect) snowfall, 2 Feb 2012, Finland Energy & telecommunication infrastructure Feezing rain, Dec 2010, Moscow Heavy snow load, Nov 2005, Germany Heavy snowfall, Feb 2013, Romania Freezing rain, Feb 2014, Slovenia (AP Photo/Vadim Ghirda) Railways Freezing rain, Feb 2014, Slovenia

Hazard identification – Surveys with stakeholders 28 CI stakeholders from the sectors: Road management Railways Power transmission Telecommunication Rescue services Most impacting phenomena: Windstorms Heavy rainfall River floods Snowfall & snowstorms Freezing rain RAIN Report: Groenemeijer et al.: Past Cases of Extreme Weather Impact on Critical Infrastructure in Europe 22.5.2019

Lat: 33 °N – 71°N Lon: 11°W – 35 °E Analysis of probabilities of hazardous winter events in the present climate Heavy snowfall Blizzards Crown snow load ≥ 6 cm/24 h ≥ 25 cm/24h Freezing rain ≥ 10 cm/24 h ≤ 0 ºC ≥ 17 m/s > 20 kg/m2 > 60 kg/m2 > 5 mm/24 h > 25 mm/24h ERA-Interim reanalysis (0.7° grid) 1981-2010 E-OBS observational dataset (0.25° grid) Methodology: Impact thresholds defined for winter phenomena Heavy snowfall and blizzards: impact thresholds applied directly on weather variables Crown snow load: an operational algorithm used in weather prediction was applied Freezing rain: freezing rain detection algorithm developed and applied Output: European gridded datasets of severe winter hazards Frequency / Probability maps for each phenomena and impact thresholds

Average number of days/year with heavy snowfall Present climate Average number of days/year with heavy snowfall >6 cm / day >25 cm / day 22.5.2019

Blizzard ≥ 10 cm/24 h, ≤ 0 oC, ≥ 17 m/s Annual probabilities (%) Blizzard ≥ 10 cm/24 h, ≤ 0 oC, ≥ 17 m/s Crown snow loads >20 kg/m2 FMI crown snow load model: rime + dry snow + wet snow + frozen snow = total snow load 22.5.2019

Annual probabilities (%) of freezing rain Present climate Annual probabilities (%) of freezing rain > 5 mm / day > 25 mm / day 22.5.2019

Projected climate changes Changes in temperature (°C) and precipitation (%) from 1971–2000 to 2070–2099, RCP8.5, multi-model means (28 GCMs) Source: K. Ruosteenoja

What are the future projections for severe winter weather events? Projected climate changes Changes in temperature (°C) and precipitation (%) from 1971–2000 to 2070–2099, RCP8.5, multi-model means (28 GCMs) 6 RCMs from EURO-CORDEX simulations Spatial resolution: 0.44° Time resolution: 3–6 h Scenarios: RCP4.5 (intermediate emissions) RCP8.5 (high emissions) Time period: 1971–2000 2021–2050 2071–2100 0.44° grid (≈50 km) → Multi-model mean: the mean change of six models compared to the reference period, for all the thresholds → Statistical significance of changes calculated with non-parametric Wilcoxon signed-rank test Source: K. Ruosteenoja

Changes in annual probabilities by 2071-2100 Snowfall Blizzard >6 cm/day >25 cm/day New risk management and adaptation strategies might be needed!

Crown snow load > 20 kg/m2 Changes in annual probabilities by 2071-2100 Crown snow load > 20 kg/m2 Freezing rain > 5mm/day

Summary Present climate: Extreme snow events have the highest probability in northern Europe and the Alpine region, severe snowfall impacting mainly road and rail infrastructure are frequent also over Eastern Europe Severe freezing rain impacts most frequently Eastern and South-Eastern Europe, and southern coast of Norway Future climate: Probabilities of snow-related hazards are projected to decrease over a large part of Europe but in N, NE Europe those may increase Northward shift in the occurrence of severe freezing rain: slight decrease in probability in central Europe but intensification in Fennoscandia and Northern Russia Finland: increased risk of hazardous winter phenomena → challenges for risk management and adaptation strategies RAIN reports and Pan-European gridded data sets of severe weather probability are publicly available for end-users: https://data.4tu.nl/repository/collection:ab70dbf9-ac4f-40a7-9859-9552d38fdccd doi:10.4121/collection:ab70dbf9-ac4f-40a7-9859-9552d38fdccd 22.5.2019

9 energy-relevant pan-European indicators of climate trends and variability 2016-2018 http://clim4energy.climate.copernicus.eu/