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21ST CENTURY CHANGES IN THE NORDIC CLIMATE: UNCERTAINTIES DERIVED FROM AN ENSEMBLE OF
REGIONAL CLIMATE MODEL SIMULATIONS
Seasonal mean temperature, precipitation and wind speed over the Nordic
region are analysed in an ensemble of 16 regional climate model (RCM)
simulations for 1961-2100. To construct the ensemble we have used the
Rossby Centre RCM with boundary conditions from seven global climate
models (GCMs) under four emission scenarios. Most of the simulations were
downscaling experiments of GCMs forced by the emission scenario SRES
A1B (Nakićenović and Swart, 2000). One of the GCMs was run three times
under A1B differing only in initial conditions. The Rossby Centre ensemble
and the more large-scale European climate change signal has earlier been
documented by Kjellström et al. (2010).
Erik Kjellström*, Grigory Nikulin, Ulf Hansson, Gustav Strandberg and Anders UllerstigSwedish Meteorological and Hydrological Institute, S-601 76 Norrköping, Sweden,
*e-mail: [email protected]
50A1BIPSL-CM4 (IPSL, France)20
25low (Q3)19
50high (Q16)18
50low (Q3)17
50A1Bref (Q0)HadCM3 (Hadley Centre, UK)
16
50B115
12.514
2513
5012
5011
50A1B10
50A2ECHAM5 (MPI-met, Germany)9
50B28
50A2ECHAM4 (MPI-met, Germany)7
50B26
50A1B5
50A2CCSM3 (NCAR, USA)4
253
50A1BBCM (NERSC, Norway)2
50A1BArpège (CNRM, France)1
Horisontal resolution (km)Emission scenarioAOGCM (Institute, country)
No
50A1BIPSL-CM4 (IPSL, France)20
25low (Q3)19
50high (Q16)18
50low (Q3)17
50A1Bref (Q0)HadCM3 (Hadley Centre, UK)
16
50B115
12.514
2513
5012
5011
50A1B10
50A2ECHAM5 (MPI-met, Germany)9
50B28
50A2ECHAM4 (MPI-met, Germany)7
50B26
50A1B5
50A2CCSM3 (NCAR, USA)4
253
50A1BBCM (NERSC, Norway)2
50A1BArpège (CNRM, France)1
Horisontal resolution (km)Emission scenarioAOGCM (Institute, country)
No
Different AOGCMs
Different initial conditions
Different modelformulation (GCM)
Different emissionscenarios
Different horizontalresolution
All simulations on the ENSEMBLES grid
with RCA3
The Baltic Sea Iceland
0 1 2 3 4 5 6−2
0
2
4
6
8
10
12
14
A1 B1C1
E1
F1
G1
H1
I1
J1K1
L1
M1N1
O1
P1
A2
B2C2
E2
F2
G2
H2
I2
J2
K2
L2
M2
N2
O2
P2
A3
B3C3
E3
F3
G3
H3
I3 J3
K3
L3
M3
N3
O3
P3
A −ECHAM5−r1B −ECHAM5−r2C −ECHAM5−r3D −HADCM3−lowE −HADCM3−refF −HADCM3−highG −BCMH −CNRMI −CCSM3J −IPSLK −CCSM3L −ECHAM4M −ECHAM5−r1N −CCSM3O −ECHAM4P −ECHAM5−r1
Temperature change (oC)
Win
d sp
eed
chan
ge (
%)
0 1 2 3 4 5 6−8
−6
−4
−2
0
2
4
A1B1
C1
E1
F1
G1
H1
I1
J1
K1
L1
M1N1
O1
P1
A2B2
C2 E2
F2
G2
H2
I2
J2
K2
L2
M2
N2
O2
P2
A3
B3
C3 E3
F3
G3
H3
I3
J3
K3
L3
M3
N3
O3
P3
A −ECHAM5−r1B −ECHAM5−r2C −ECHAM5−r3D −HADCM3−lowE −HADCM3−refF −HADCM3−highG −BCMH −CNRMI −CCSM3J −IPSLK −CCSM3L −ECHAM4M −ECHAM5−r1N −CCSM3O −ECHAM4P −ECHAM5−r1
Temperature change (oC)
Win
d sp
eed
chan
ge (
%)
0 1 2 3 4 5 6−4
−2
0
2
4
6
A1
B1
C1
E1
F1
G1
H1I1
J1
K1
L1
M1
N1
O1
P1
A2
B2C2
E2F2
G2
H2
I2
J2
K2
L2
M2
N2
O2
P2
A3B3C3
E3
F3
G3
H3I3
J3
K3
L3
M3N3
O3
P3
A −ECHAM5−r1B −ECHAM5−r2C −ECHAM5−r3D −HADCM3−lowE −HADCM3−refF −HADCM3−highG −BCMH −CNRMI −CCSM3J −IPSLK −CCSM3L −ECHAM4M −ECHAM5−r1N −CCSM3O −ECHAM4P −ECHAM5−r1
Temperature change (oC)
Win
d sp
eed
chan
ge (
%)
Nordic mainland
Figure 3. Change in annual mean wind speed versus change in T2m relative to 1961-1990. The letters
indicate which driving GCM that has been used. The numbers for which time period the change is calculated:
(1) 2011-2040, (2) 2041-2070 and (3) 2071-2100. Colours indicate emission scenarios (A2-red, A1B-black,
B2-blue, B1-green). The grey line is a least-square fit to the data.
A changing wind climate?
Figure 1. Change in annual mean precipitation versus change in T2m relative to 1961-1990. The letters indicate
which driving GCM that has been used. The numbers for which time period the change is calculated: (1) 2011-
2040, (2) 2041-2070 and (3) 2071-2100. Colours indicate emission scenarios (A2-red, A1B-black, B2-blue, B1-
green). The grey line is a least-square fit to the data.
Changing precipitation
Annual mean Summer (JJA)Winter (DJF)
Figure 2. Change in P-E versus change in T2m relative to 1961-1990 for the Nordic mainland. The letters
indicate which driving GCM that has been used. The numbers for which time period the change is calculated:
(1) 2011-2040, (2) 2041-2070 and (3) 2071-2100. Colours indicate emission scenarios (A2-red, A1B-black,
B2-blue, B1-green). The grey line is a least-square fit to the data.
A wetter climate?
0 1 2 3 4 5 6
0
5
10
15
20
25
30
A1
B1
C1
D1
E1F1
H1
I1
J1
M1
O1
P1
A2
B2
C2
D2
E2
F2
H2
I2
J2
M2
O2
P2
A3
B3
C3
D3
E3
F3
H3
I3
J3
M3
O3
P3
Temperature change (oC)
P−
E c
hang
e (%
)
A A1B−ECHAM5−r1B A1B−ECHAM5−r2C A1B−ECHAM5−r3D A1B−HADCM3−lowE A1B−HADCM3−refF A1B−HADCM3−high
H A1B−CNRMI A1B−CCSM3J A1B−IPSL
M A2−ECHAM5−r1
O B2−ECHAM4P B1−ECHAM5−r1
0 2 4 6 8 10
0
5
10
15
20
25
30
35
A1
B1
C1
D1
E1
F1H1
I1
J1
M1
O1
P1
A2
B2
C2
D2E2F2
H2
I2
J2M2
O2
P2
A3
B3
C3
D3E3
F3
H3
I3 J3
M3
O3
P3
Temperature change (oC)
P−
E c
hang
e (%
)
A A1B−ECHAM5−r1B A1B−ECHAM5−r2C A1B−ECHAM5−r3D A1B−HADCM3−lowE A1B−HADCM3−refF A1B−HADCM3−high
H A1B−CNRMI A1B−CCSM3J A1B−IPSL
M A2−ECHAM5−r1
O B2−ECHAM4P B1−ECHAM5−r1
0 1 2 3 4
0
20
40
60
80
100
120
140
160
A1
B1
C1
D1E1
F1H1
I1
J1
M1O1
P1A2
B2C2
D2
E2
F2H2
I2
J2
M2O2
P2
A3B3C3
D3
E3F3
H3
I3
J3
M3
O3
P3
Temperature change (oC)
P−
E c
hang
e (%
)
A A1B−ECHAM5−r1B A1B−ECHAM5−r2C A1B−ECHAM5−r3D A1B−HADCM3−lowE A1B−HADCM3−refF A1B−HADCM3−high
H A1B−CNRMI A1B−CCSM3J A1B−IPSL
M A2−ECHAM5−r1
O B2−ECHAM4P B1−ECHAM5−r1
0 1 2 3 4 5 6−5
0
5
10
15
20
25
30
A1
B1
C1
D1E1F1
G1H1
I1
J1
K1 L1
M1
N1
O1
P1
A2
B2
C2
D2E2
F2
G2
H2
I2
J2
K2
L2
M2N2
O2
P2
A3 B3
C3
D3E3
F3
G3
H3
I3
J3
K3
L3M3
N3
O3
P3
Temperature change (oC)
Pre
cipi
tatio
n ch
ange
(%
) A A1B−ECHAM5−r1B A1B−ECHAM5−r2C A1B−ECHAM5−r3D A1B−HADCM3−lowE A1B−HADCM3−refF A1B−HADCM3−highG A1B−BCMH A1B−CNRMI A1B−CCSM3J A1B−IPSLK A2−CCSM3L A2−ECHAM4M A2−ECHAM5−r1N B2−CCSM3O B2−ECHAM4P B1−ECHAM5−r1
The Baltic Sea IcelandNordic mainland
0 1 2 3 4 5 6−5
0
5
10
15
20
25
30
A1B1C1D1
E1
F1
G1
H1
I1
J1
K1
L1
M1
N1
O1
P1
A2B2
C2
D2
E2
F2
G2H2
I2
J2
K2
L2
M2
N2
O2
P2
A3B3
C3
D3
E3
F3
G3
H3
I3
J3
L3
M3
N3O3
P3
Temperature change (oC)
Pre
cipi
tatio
n ch
ange
(%
) A A1B−ECHAM5−r1B A1B−ECHAM5−r2C A1B−ECHAM5−r3D A1B−HADCM3−lowE A1B−HADCM3−refF A1B−HADCM3−highG A1B−BCMH A1B−CNRMI A1B−CCSM3J A1B−IPSLK A2−CCSM3L A2−ECHAM4M A2−ECHAM5−r1N B2−CCSM3O B2−ECHAM4P B1−ECHAM5−r1
0 1 2 3 4 5 6−5
0
5
10
15
20
25
30
A1
B1
C1
D1E1F1
G1H1
I1
J1
K1
L1
M1
N1
O1
P1
A2
B2
C2
D2
E2
F2G2
H2
I2
J2
K2
L2
M2N2
O2
P2
A3
B3
C3
D3
E3
F3
G3
H3
I3
J3
K3
L3
M3
N3
O3
P3
Temperature change (oC)
Pre
cipi
tatio
n ch
ange
(%
) A A1B−ECHAM5−r1B A1B−ECHAM5−r2C A1B−ECHAM5−r3D A1B−HADCM3−lowE A1B−HADCM3−refF A1B−HADCM3−highG A1B−BCMH A1B−CNRMI A1B−CCSM3J A1B−IPSLK A2−CCSM3L A2−ECHAM4M A2−ECHAM5−r1N B2−CCSM3O B2−ECHAM4P B1−ECHAM5−r1
The Rossby Centre ensemble
AcknowledgementsPart of the simulations and subsequent analysis work has been funded by the European ENSEMBLES (GOCE-CT-2003-505539) project, the Nordic
Climate and Energy Systems (CES) project and the Swedish Mistra-SWECIA programme funded by Mistra (the Foundation for Strategic
Environmental Research). The model simulations were made on the climate computing resource Tornado funded with a grant from the Knut and Alice
Wallenberg foundation. The institutes providing the global model data used as boundary conditions are kindly acknowledged. We are grateful for the
E-OBS dataset from the EU-FP6 project ENSEMBLES (http://www.ensembles-eu.org) and the data providers in the ECA&D project
(http://eca.knmi.nl).
ReferencesKjellström, E., Nikulin, G., Hansson, U., Strandberg, G. and Ullerstig, A., 2011. 21st century changes in the European climate: uncertainties derived
from an ensemble of regional climate model simulations. Tellus, 63A(1), 24-40. DOI: 10.1111/j.1600-0870.2010.00475.x
Nakićenović, N., and R. Swart (eds.), 2000. Special Report on Emissions Scenarios. A Special Report of Working Group III of the Intergovernmental
Panel on Climate Change. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, 599 pp.
The ensemble is used to; i) evaluate the simulated Nordic climate against observed
climatologies for 1961-1990, ii) assess future climate change and iii) illustrate
uncertainties in future climate change related to natural variability, boundary
conditions and emissions.
� Biases in temperature and precipitation in the 1961-1990 period are strongly
related to errors in the large-scale circulation in the GCMs (Fig. 5).
� Statistically significant increases in temperature are seen for all of the Nordic
region already in the next decades (Fig. 4).
� Precipitation increases in northern Europe and most so in winter (Figs. 1 & 4).
� Generally wetter conditions in the future (Fig. 2).
� Wind speed changes are generally small. Increase in wind speed are found in
parts of the northern seas and decreases in many other areas (Figs. 3 & 4).
� Uncertainty largely depends on choice of GCM. This strong dependency is
related to their representation of changes in the large-scale circulation.
� The uncertainty related to forcing (i.e. emission scenario) is most important by
the end of the century while natural variability sometimes dominates the uncertainty
on local to regional scales in the nearest few decades.
Summary
CTL
-20-16-12
-8-4048
1216
oC
Tem
pera
ture
SCN1 - CTL SCN2 - CTL SCN3 - CTL
0 1 2 3 4 5 6 7 8
oC
RCA3(6GCMs) DJF | CTL: 1961-1990 | SCN1: 2011-2040 | SCN2: 2041-2070 | SCN3: 2071-2100
0153045607590
105120150200300
Pre
cipi
tatio
n
mmmonth
-60 -40 -20 0 20 40 60 %
23456789
1011
m/s
Win
d
100210061010
10141018
1022
-1-1
1
1
1
22
-1 -0.5 0 0.5 1 1.5 2 m/s
CTL
05
10
15
20
25
3035
oC
Tem
pera
ture
SCN1 - CTL SCN2 - CTL SCN3 - CTL
0 1 2 3 4 5 6
oC
RCA3(6GCMs) JJA | CTL: 1961-1990 | SCN1: 2011-2040 | SCN2: 2041-2070 | SCN3: 2071-2100
0153045607590
105120150200300
Pre
cipi
tatio
n
mmmonth
-60 -40 -20 0 20 40 60 %
12
3
4
5
6
78
m/s
Win
d
10131013
1013
10151017
-0.5
-0.5
-0.50.5
-1 -0.5 0 0.5 1 1.5 2 m/s
Figure 4. Six-member A1B ensemble (marked in orange in the table) means of T2m (top), P (middle), and W10m and
MSLP (lower) for 1961-1990 (left) and the respective changes in 2011-2040, 2041-2070 and 2071-2100 compared
to 1961-1990 in the three rightmost columns. Only differences significant at the 5% significance level are shown.
For MSLP all changes are shown but statistically significant differences are indicated with thick lines.
Winter (DJF) Summer (JJA)
Gradual changes with 6 different AOGCMs under A1B
Figure 5. (top, left) Mean T2m (colour, °C, E-OBS) and MSLP (hPa, ERA40) and biase s of T2m and MSLP in the
RCA3 simulations driven by (top, middle) the ERA40 reanalysis, (middle and bottom rows) six different AOGCMs
and (top, right) their ensemble mean. Only T2m differences significant at the 5% significance level are shown.
Correspondingly, statistically significant differences for MSLP are indicated with thick lines.
E-OBS
10061010
1014
1018
1018
-20-16-12
-8-4048
1216
oC
2m temperature Winter (DJF) 1961-1990RCA3 (ERA40)
-2
-2
2
2
RCA3 (6 GCMs)
-2
-2
2
2
2
-2-2
2 2
RCA3 (ECHAM5)
-2
-2
-2
-2
-2
-2
2
2
2
2
RCA3 (HADCM3)
-2
-2
2
2
-2-2
-2
RCA3 (BCM)
-10
-6
-2
-2
-2
-2
2
2
2
2
6 6
6
-10
-6
-2
6
RCA3 (CCSM3)
-10
-6
-6
-2
-2
2
6
6
6
-10-6
-6
-26
RCA3 (CNRM)
-2
-2
2
2
2
2
2
2 2 2
2
2
2
6
6
2
2
22
6RCA3 (IPSL)
-2
-2
2
2
2
6
6
6
6
-2
26
6
-6 -4 -2 0 2 4 6
oC RCA3(ERA40, GCMs) - E-OBS
E-OBS
101210141016
0
6
12
18
24
30
oC
2m temperature Summer (JJA) 1961-1990RCA3 (ERA40)
2
2
2 2
2
2
2
2
2
2
2
RCA3 (6 GCMs)
-2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
RCA3 (ECHAM5)
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2 2
2
2RCA3 (HADCM3)
-6
-2
-2
-2
-2
-2
-2
-2 -2
-2
-2
-2 -2
RCA3 (BCM)
-2
-2
-2
-2
-2
-2
-2
-2
-2
-2
-2
2
2
6
6
6
-2
-2
2
6
RCA3 (CCSM3)
-2
2
2
2
2
2
2
2
2
2
2
2
2
22
2RCA3 (CNRM)
2
2
2
2
2
2
2
2
2
2
2
6
6
6
6
6
6
6
22
2 6
RCA3 (IPSL)
2
2
6
10
10
2
2
6
-6 -4 -2 0 2 4 6
oC RCA3(ERA40, GCMs) - E-OBS
Biases in the control periodWinter (DJF) Summer (JJA)