Past and future climate development in Longyearbyen, Svalbard

Transcription

1 Past and future climate development in Longyearbyen, Svalbard Eirik J. Førland 1,2 and Ketil Isaksen 1 1). Norwegian Meteorological Institute 2). Norwegian Centre for Climate Services Svalbard Science Conference 2017, Fornebu, 8 November 2017

2 Several landslides and avalanches last summer and autumn on Spitsbergen - related to heavy rainfall, but what about the influence of the record high thaw depth? Longyeardalen, Carolinedalen, is the Norwegian Steintippdalen, government's key advisor in construction and property affairs, building Larsbreen, commissioner, property manager and property developer. Statsbygg owns and operates several buildings and constructions in Svalbard, and wants to take into consideration consequences of long-term climate changes in the region. Statsbygg has commisioned parts of this study 30. juni 2016 Foto: John Christian Nygaard 2

3 SVALBARD AIRPORT: WINTER TEMPERATURE Past development: Linear trends (DJF): : 0,35 C/decade : 2,23 C/decade Average temperature (DJF): : -14,0 C Future development: (from to ) Different emissions scenarios Different models

4 SVALBARD AIRPORT: ANNUAL TEMPERATURE Annual: (Average:- 5,9 C) Linear trend: : 0,28 C/dec : 1,26 C/dec Seasonal trends ( C/dec), Winter: 0,35 Spring: 0,41 Summer: 0,14 Autumn: 0,26

5 REASONS FOR WARMING AT SVALBARD Presentation yesterday by Ketil Isaksen: The recent warming on Svalbard and its relation to atmospheric circulation (AC) and sea ice cover (JGR, 2016) Sites: Svalbard Airport, Ny-Ålesund, Isfjord Radio, Hornsund, Barentsburg Changes in frequencies of AC types have a minor role on recent warming: Contribute ~10% annually and ~ 25% in winter A major part of the warming is attributed to changes in air mass characteristics (higher temperatures) and mainly linked to a few AC types What causes changes in air mass characteristics? Regional influence of reduced sea-ice in seas surrounding Spitsbergen Local effects of reduced wintertime ice cover on the fjords outside stations Regional influence of increased sea surface temperatures Other mechanisms for large-scale Arctic warming

6 From global emissions to climate projections for Svalbard Global emission scenarios (RCPs) Global climate model Dynamical downscaling: Regional climate model (Arctic CORDEX) Empirical statistical downscaling Bias-adjustment of temperature and precipitation Local projections

7 FUTURE TEMPERATURE Projected annual temperatures for Longyearbyen during for RCP8.5. Red and grey shading indicate ensemble spread of GCMs resp. RCMs (Arctic CORDEX). White line indicates simulation (MPI-ESM-LR) used in MET dynamical downscaling. Black line is observations from Svalbard Airport, red line is median for GCM simulations, Blue and green lines are MET simulations (CCLIM) with spatial resolution 25 and 2,5 km.

8 FUTURE TEMPERATURE, Longyearbyen Estimated temperature change (degc) in Longyearbyen from to Estimates are based on results from GCM, RCM and ESD-simulations. Values are given for three emission scenarios (RCPs). RCP2.6 RCP4.5 RCP8.5 Annual 3,6 6,5 9,2 Winter (DJF) 5,7 9,1 13,4 Spring (MAM) 3,7 6,7 9,7 Summer (JJA) 1,1 2,6 4,0 Autumn (SON) 4,2 6,7 9,4

9 PRECIPITATION Average precipitation (mm) at Svalbard Airport Annual Winter (DJF) Spring (MAM) Summer (JJA) Autumn (SON) Highest 1-day rainfall (mm) Svalbard Airport Ny-Ålesund 43,2 5.Aug ,0 30.Jan ,7 8.Nov ,8 8.Nov ,2 9.Feb ,0 1.Dec ,0 5.Mar ,0 12.Mar ,1 11.Jul ,0 9.Oct 2002

10 ANNUAL SNOW AMOUNT AS FRACTION OF TOTAL PRECIPITATION

11 FUTURE PRECIPITATION (Based on Arctic CORDEX projections) Annual and seasonal precipitation will increase towards 2100 Projected annual precipitation based on median values for RCP8.5: + 38 % (RCP4.5: +28 % and RCP2.6:+21 %) There will be an increase in precipitation intensity as well as in number of days with heavy rainfall During the winter half year the number of events with rainfall will triple compared to present conditions

12 SNOW All simulations indicate reduced length of snow season towards Wintertime almost all precipitation will still fall as snow in inland areas West coast of Spitsbergen: Larger fraction of wintertime precipitation as rain Generally, the average seasonal snow depth will decrease, but may increase wintertime in some inland areas Modelled maximum snow depth (meters) for present (left) and future (middle) climate. Right: Changes in max snow depth. Results based on MET-RCM 2,5 km simulations, RCP8.5

13 PERMAFROST: Janssonhaugen, Svalbard Mean annual ground temperature Since 2000 ground temperature at 20 m depth has increased by 0,8 C/decade Future: Permafrost degradation is modeled by the end of the century in low-lying coastal areas

14 Uncertainty in projections is connected to: Natural variations Simplifications and errors in climate models Emission scenarios Specific for the Svalbard region: Limited climate series for model validation Biased sea-ice modelling Projections indicate continued warming up to 2100: Annual: 4 to 9 C Winter: 6 to 13 C Permafrost degradation in low-lying coastal areas

15 Norwegian Centre for Climate Services Climate report: «Svalbard 2100» (Spitsbergen, Bjørnøya, Hopen, Oceans) Assessment: Past-Present-Future climate Deadline: 2018 Topics: Atmosphere Hydrology incl. snow and glaciers Permafrost, avalanches Ocean climate incl. sea ice Sea level Contributors: MET, NVE, UniR IMR: Institute for Marine Research NERSC: Nansen Center NGI: Norwegian Geotechnical Institute NP: Norwegian Polar Institute Kartverket: Norw. Mapping Authority Univ in Bergen and Oslo UNIS: Univ Centre in Svalbard

16 THANK YOU! Report available at Norwegian Centre for Climate Services: