Changes in snow season in Lapland from regional climate models

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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,

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CO2 EMISSIONS PROFILESunder IPCC SRES scenarios
Used here
Source IPCC
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GLOBAL TEMPERATURE RISE due to four SRES
emissions scenarios
Used here
Source Hadley Centre
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GCM used for all regional models HadAM3H
1961-1990 runs used control 2071-2100 with A2
forcing as scenarios
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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
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Sensitivity due to GCM and RCM resolution
Hadley 50km
Hadley 25km
ECHAM
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PRUDENCE http//prudence.dmi.dk/ set of models
100km
T42
Meteo
DMI
Had
Rossby
Es
ETH
IPCC
MPI
GKSS
12 km
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Regional climate models

• 6 for snow season
• DMI (Denmark)
• ETH (Swiss)
• GKSS (Germany)
• KNMI (Netherlands)
• MPI (Germany)
• SMHI (Sweden)

• 9 for temperature
• CNRM (France)
• DMI (Denmark)
• ETH (Switzerland)
• HC (UK)
• GKSS Germany)
• KNMI (Netherlands)
• MET NO (Norway)
• MPI (Germany)
• SMHI (Sweden)

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Europe view
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.
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).
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Europe view
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
Simulated change in average summer temperature
(upper panel) from the period 1961-1990 to the
period 2071-2100.
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Lapland Snow Season - Control
Comparison of 6 snow models
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Lapland Snow Season - Forecast
Comparison of 6 snow models
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Lapland Snow Season - Change
Changes in snow season
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Snow Season Change 1975-2085
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Chance of No Snow at Christmas Time (lt10 kg/m2)
Models show winters will be wetter, but less snow
cover More ice More rain
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Temperature annual cycle 2085 9 models Ylläs
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Temperature annual cycle 1975-2085 mean
differences
Winters warmer by about 4-5C Summers warmer by
about 2-3C
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Reduced number of freezing days - Lapland
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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
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Impact on snow season greater further South
Rovaniemi in 2085 like Tampere in 1975
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Conclusions

• 4-5C/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