NEW-CALEDONIA'SCLIMATE
OF THE FUTURE
V. Cavarero, A. Leroy,A. Ganachaud, J. Lefèvre,C. Menkes, A. Peltier,
M. Lengaigne
Meteo-France & IRD
April 2012
Simulations Observations Statistical downscaling Results Conclusion 2
STATISTICAL DOWNSCALING
SIMULATIONS
RESULTS
OBSERVATIONS
Simulations Observations Statistical downscaling Results Conclusion 3
STATISTICAL DOWNSCALING
SIMULATIONS
RESULTS
OBSERVATIONS
Simulations Observations Statistical downscaling Results Conclusion 4
Choice of IPCC models
We used 6 models (4th IPCC report in 2007) :I CSIRO Mk3.5d(2005)
I GFDL-CM2.0 (2004)
I GFDL-CM2.1 (2004)
I MIUB ECHO-G (1999)
I ECHAM5/MPI-OM (2004)
I MRI-CGCM2.3.2.a (2001)
which correctly represent the SPCZ and ENSO :
I good representation of the SPCZ mean state(mean latitude and slope),
I good representation of ENSO,
I good variability of SPCZ associated with ENSO.
Simulations Observations Statistical downscaling Results Conclusion 5
Hypotheses : greenhouse gases emissions scenarios
Figure 1: Global average carbon dioxidconcentrations. Source : AR4, IPCC.
Control scenario over 1961-2000 :
I 20c3m (greenhouse gases
concentrations increasing in accordance
with 20th century observations).
2 scenarios over 2046-2065 and2081-2100 :
I SRES A2 (more CO2 emissions),
I SRES B1 (less CO2 emissions).
Simulations Observations Statistical downscaling Results Conclusion 6
Climate models' resolution
Figure 2: New-Caledonia stations' network, and CSIRO gridpoints (200 × 200 km).
Simulations Observations Statistical downscaling Results Conclusion 7
STATISTICAL DOWNSCALING
SIMULATIONS
RESULTS
OBSERVATIONS
Simulations Observations Statistical downscaling Results Conclusion 8
Observed trends in temperatures and rainfall
Figure 3: Annual average maximum temperatures at Noumeaover 1970-2009, after homogenization.
I Maximum temperatures :+ 0.2◦C per decade,
I Minimum temperatures :+ 0.3◦C per decade,
(16 stations - average).
Figure 4: Average annual rainfall at Lifou, over 1961-2008,after homogenization.
I Rainfall : no signi�cant trend
(29 stations - average).
Simulations Observations Statistical downscaling Results Conclusion 9
STATISTICAL DOWNSCALING
SIMULATIONS
RESULTS
OBSERVATIONS
Simulations Observations Statistical downscaling Results Conclusion 10
Quantile-quantile method : principle
Figure 5: Minimum temperatures, year 1978 (observations, raw and corrected CSIRO20c3m simulations. In red : 07/28/1978 and 08/18/1978 correction values (in ◦C).
Déqué M. 2007., Frequency of precipitation andtemperature extremes over France in an anthropogenic scenario.Global and Planetary Change, 57, 16-26.
Simulations Observations Statistical downscaling Results Conclusion 11
STATISTICAL DOWNSCALING
SIMULATIONS
RESULTS
OBSERVATIONS
Simulations Observations Statistical downscaling Results Conclusion 12
Maximum temperatures evolution
1970 1980 1990 2000 2010 2020 2030 2040 2050 2060 2070 2080 2090 210024.0
24.5
25.0
25.5
26.0
26.5
27.0
27.5
28.0
28.5
29.0
29.5
30.0
30.5
31.0
TE
MP
ER
ATU
RE
( °
C)
+1
+1.4 +1.4
+2.7
OBSERVATIONS20c3mSRES B1SRES A2
NOUMEA : TEMPERATURES MAXIMALES
ANNEE
Figure 6: Annual average maximum temperature, observations and simulations, atNoumea.
Simulations Observations Statistical downscaling Results Conclusion 13
Rainfall evolution
1970 1980 1990 2000 2010 2020 2030 2040 2050 2060 2070 2080 2090 21000
200
400
600
800
1000
1200
1400
1600
1800
2000
2200
PR
EC
IPIT
ATIO
NS
(m
m/jo
ur)
−43 −63 −25
+12
OBSERVATIONS20c3mSRES B1SRES A2
NOUMEA : PRECIPITATIONS ANNUELLES
ANNEE
Figure 7: Annual rainfall : observations and simulations, at Noumea.
Simulations Observations Statistical downscaling Results Conclusion 14
Changes in South Paci�c Rainfall
Figure 8: Change in DJF (left) and JJA (right) precipitation (mm/day) for last twodecades of A2 simulation (2080-2099) compared with last two decades of 20th centurysimulation (1980-1999). Multi-Model Mean (AR4 16 models). Contour lines indicatemean precipitation for 20th century (1980-1999). Contour interval is 2 mm/day.Source : Brown J.R., doi :10.1007/s00382-011-1192-0.
Simulations Observations Statistical downscaling Results Conclusion 15
Example of consequence : dengue fever risk
Mean index
� Tmax > 32◦C �
(in days)
Percentage of years
such as the index is
greater than 12 days
1970-2008 Observations 8 21 %
1971-1999 20c3m 9 29 %
2046-2064SRES B1 16 47 %
SRES A2 21 66 %
2081-2099SRES B1 21 73%
SRES A2 44 95%
Figure 9: Mean index � Tmax > 32◦C � = Number of days such as maximumtemperature are higher than 32◦C at Noumea, for january-february-march.Cells are colored if the number of days is greater than 12.
Simulations Observations Statistical downscaling Results Conclusion 16
Conclusion
Main results
I +1◦C (SRES B1), +1.4◦C (SRES A2) from 1971-1999 until2046-2064,
I +1.4◦C (SRES B1), +2.7◦C (SRES A2) from 1971-1999 until2081-2099,
I Annual rainfall not signi�cantly a�ected,
I More years favorable to outbreaks of dengue fever.
Future improvement
I Use new climatic simulations (next IPCC report : AR5),
I Apply downscaling method to di�erent weather types.
Simulations Observations Statistical downscaling Results Conclusion 18