Table S1 present the names and periods of RegCM4 experiments.
Table S1 – The names, periods and scenarios (RCP4.5 and RCP8.5) of RegCM4 simulations
forced by HadGEM2 (CERegHad and BGRegHad), MPI (CERegMPI) and GFDL
(CERegGFDL) GCMs. The CE and BG indicate, respectively, that RegCM4 simulations used
CLM-Emanuel and BATS-GE schemes.
Periods/
CERegHad
RCP4.5
BGRegHad
Simulations
RCP8.5
RCP8.5
1975-2006
X
2020-2050
X
X
X
2070-2098
X
X
X
RCP4.5
X
CERegMPI
CERegGFDL
RCP8.5
RCP8.5
X
X
X
X
X
X
X
X
As shown in Figure S1, each GCM exhibits a different time evolution of ONI amplitude
and variability. Figure S2 shows the mean SST in Niño 3.4 region and the ONI SD from the
GCMs (GFDL, MPI and HadGEM2) in the present climate and in the near- and far-future
RCP4.5 and RCP8.5 climates. In both present and near-future climates there is a large
agreement between the modeled mean SST of ~26oC in the Niño3.4 area, but the spread of the
ONI variability (SD) is large. For the present climate, HadGEM2 has a small ONI variability
and maintains this characteristic in the future for both RCP4.5 and RCP8.5, but it projects a
larger warming of Niño3.4 SST in the RCP8.5 far-future scenario, when SST reaches ~30oC.
Considering the three time periods, while GFDL projects a negative trend of the ONI
variability the opposite occurs in the MPI, such that for RCP8.5 far-future climate both models
indicate a similar mean SST of ~28.5-29.0oC and SD of ~1.0-1.2oC. According to Meehl et al.
(2006) the reduction of amplitude and variability of ENSO in GCMs that include the increase
of greenhouse gases (GHCs) occur due to the change in the base state SST in the equatorial
Pacific, which is stronger and statistically significant when the increase in GHCs is larger.
However, while there is some confidence about the past intensification of ENSO, this matter is
as yet inconclusive for future warming scenarios with some models showing intensification
and others weakening (Guilyardi 2006; Meehl et al. 2006; DiNezio et al. 2012)
(a)
1.35
(b)
0.92
(c)
0.69
Figure S1 - Three month running mean of the ONI (oC) for the three time periods (left: present,
center: near-future, right: far-future climates) from: (a) GFDL RCP8.5, (b) MPI RCP8.5, and
(c) HadGEM2 RCP4.5 (green and light blue) and RCP8.5 (purple and dark blue). The numbers
at the bottom of each panel indicate the ONI SD for the cumulative periods of each GCM.
P
1.6
HadGEM8.5
GFDL8.5
MPI8.5
HadGEM4.5
o
SD ONI index ( C)
N
1.4
1.2
1.0
0.8
P
26
27
F
F
N
0.6
25
F
N
28
29
30
31
O
SST Nino3.4 ( C)
Figure S2 - Scatter diagram for the average SST in the Niño3.4 area and ONI SD for the
present-day (P), near-future (N) and far-future (F) climates in the RCP8.5 scenarios of
HadGEM2, GFDL and MPI and RCP4.5 only for HadGEM2.
References
DiNezio, PN, et al. (2012) Mean climate controls on the simulated response of ENSO to
increasing greenhouse gases. J Climate, 25: 7399-7420.