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/Simulations / CERegHad
RCP8.5 RCP4.5 / BGRegHad
RCP8.5 RCP4.5 / CERegMPI
RCP8.5 / CERegGFDL
RCP8.5
1975-2006 / X
X
X / X
X / X / X / X
2020-2050 / X / X / X / X
2070-2098 / 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)
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.
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.