Changes in snow season in Lapland from regional climate

models

John Moore1,2, and Aslak Grinsted1

1 Arctic centre, University of Lapland

Rovaneimi, Finland 2 Thule Institute, University of Oulu,

CO2 EMISSIONS PROFILESunder IPCC SRES scenarios

Source:IPCC

Used here

GLOBAL TEMPERATURE RISEdue to four SRES emissions scenarios

Source: Hadley Centre

Used here

GCM used for all regional models: HadAM3H

1961-1990 runs used control

2071-2100 with A2 forcing as scenarios

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

Christensen & Christensen, Nature (2003)

Sensitivity due to GCM and RCM resolution

ECHAM Hadley 50km Hadley 25km

AGCM exp forcing

HadAM3H

ARPEGE ECHAM5 CCM3

HadCM3 SRES A2

3 ensemble members 150 km BDY 1

2 mem high res.

1 member T106

2 members T80 BDY4

HadCM3 SRES B2

1 member 150 km BDY 2

1 mem high res.

ECHAM4/OPYC3 SRES A2

1 member T106 BDY 3

ARPEGE/OPA SRES B2

1 mem high res.

RCM 50km Input

P5

P9

P1 P10 P6 P2/P12 P8 P7

BDY 1 3 mem 3 mem BDY 1 1 mem 1 mem 1 mem 1 mem 1 mem 1 mem BDY 1 ini cond.

1 mem

BDY 2 1 mem 1 mem 1 mem BDY 3 1 mem BDY 4 1 mem RCM 20 km Input

P5 P9 P1 P6 P8

BDY 1 1 mem 1 mem 1 mem 1 mem 1 mem

DMIHad Rossby Es ETH IPCC MPI GKSS

MeteoT42

100km

12 km

PRUDENCE http://prudence.dmi.dk/ set of models

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)

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

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

Comparison of 6 snow models

Lapland Snow Season - Control

Comparison of 6 snow models

Lapland Snow Season - Forecast

Changes in snow season

Lapland Snow Season - Change

Ylläs Rovaniemi Pyhäend of season 0.20 0.23 0.22 days/yearstart of season 0.23 0.28 0.28 days/year

length of season 0.27 0.34 0.31 % per year

mean snow loss 0.45 0.55 0.52 % per yearmax snow thickness loss 0.29 0.39 0.36 % per year

Ylläs Rovaniemi Pyhäend of season 1 week in 34 31 32 yearsstart of season 1 week in 31 25 25 years

length of season 1 week in 16 14 14 years

Snow Season Change 1975-2085

Chance of No Snow at Christmas Time (<10 kg/m2)

Models show winters will be wetter, but less snow cover

More iceMore rain

Temperature annual cycle 2085 – 9 models Ylläs

Temperature annual cycle 1975-2085 mean differences

Winters warmer by about 4-5C

Summers warmer by about 2-3C

Reduced number of freezing days - Lapland

Ylläs Rovaniemi Pyhäblower benefits 0.03 0.08 0.08 days/year

errors 0.05 0.05 0.06 days/year

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

Tamperemean snow loss 0.72 % per year

max snow thickness loss 0.54 % per yearlength of season 0.62 % per year

Impact on snow season greater further South

Rovaniemi in 2085 like Tampere in 1975

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