1. Changes in snow season in Lapland from regional climate models John Moore 1,2, and Aslak Grinsted 1 1 Arctic centre, University of Lapland Rovaneimi, Finland 2 Thule Institute, University of Oulu,

2. CO 2 EMISSIONS PROFILES under IPCC SRES scenarios Source: IPCC Used here

3. GLOBAL TEMPERATURE RISE due to four SRES emissions scenarios Source: Hadley Centre Used here

4. GCM used for all regional models: HadAM3H 1961-1990 runs used control 2071-2100 with A2 forcing as scenarios

5. Coarse resolution GCM model with Regional model nested inside at 25 km grid point spacing Compared with 300 km grid points of GCM 50 km grid points Still not enough to show much Mountainous topography – would need less than 10 km, we only have 25 km 12.5 km grid

6. Christensen & Christensen, Nature (2003) Sensitivity due to GCM and RCM resolution ECHAM Hadley 50kmHadley 25km

7. DMIHadRossbyEs ETH IPCC MPI GKSS Meteo T42 100km 12 km PRUDENCE http://prudence.dmi.dk/ set of models

8. Regional climate models 9 for temperature –CNRM (France) –DMI (Denmark) –ETH (Switzerland) –HC (UK) –GKSS Germany) –KNMI (Netherlands) –MET NO (Norway) –MPI (Germany) –SMHI (Sweden) 6 for snow season –DMI (Denmark) –ETH (Swiss) –GKSS (Germany) –KNMI (Netherlands) –MPI (Germany) –SMHI (Sweden)

9. Simulated changes in winter (DJF) and summer (JJA) precipitation from the period 1961-1990 to 2071-2100. SMHI regional climate model with boundary conditions from the HadAM3H (left) and from the ECHAM4 (right). A future warming that will be largest in winter in northern Europe and largest in summer in southern Europe. Increased precipitation in northern Europe, especially during winter, and decreased precipitation in southern Europe during summer. Europe view

10. Simulated change in average summer temperature (upper panel) from the period 1961- 1990 to the period 2071-2100. Temperature changes in summer modest of Scandinavia compared with much of Europe To make robust forcasts of changes we need to use the long term predictions and averages over at least 30 years. This avoids to signal of climate change becoming lost in the noise of random weather Europe view

11. Comparison of 6 snow models Lapland Snow Season - Control

12. Comparison of 6 snow models Lapland Snow Season - Forecast

13. Changes in snow season Lapland Snow Season - Change

14. Snow Season Change 1975-2085

15. Chance of No Snow at Christmas Time (<10 kg/m 2 ) Models show winters will be wetter, but less snow cover More ice More rain

16. Temperature annual cycle 2085 – 9 models Ylläs

17. Temperature annual cycle 1975-2085 mean differences Winters warmer by about 4-5C Summers warmer by about 2-3C

18. Reduced number of freezing days - Lapland

19. Possible use of artificial snow making Balance between rate of decrease in days below zero, and time of start of snow cover Very large uncertaintity – little difference to benefit rate if -3C used instead of zero

20. Impact on snow season greater further South Rovaniemi in 2085 like Tampere in 1975

21. Conclusions 4-5°C/Century winter warming in Lapland More rainfall, more ice, wet slushy snow Much greater risk of dark Christmas, especially in Rovaniemi Rovaniemi 2085 like Tampere 1975 Snow season shorter by about 1 week every 15 years in Lapland Reduced snow pack thickness due to less snow and denser snow Average snow affected more than peak snow Bigger changes further South