2.2.1. GCM Outputs

In the IPCC 5th assessment report, four representative concentration pathways (RCPs) are normally used as a basis for future climate modelling: one very high baseline emission scenario (RCP8.5), two medium stabilization scenarios (RCP4.5 and RCP6) and one mitigated scenario (RCP2.6) (Table 1).

**Table 1.** Representative concentration pathways (RCPs), their radiative forcing, emissions (CO2 equivalent and growth rate %) and temperature increase.


The current study intended to include emission scenarios, covering a wider range of Radiative forcing and future temperature anomaly, while remaining close to the reality and considering RCP's showing minimum differences with the 2005 onwards actual observed CO2 emission trend and growth rates. Keeping these prerequisites in mind, out of the four options: RCP2.6 was not considered in the current selection as it seemed to be the least likely [18,21] and the mitigation effort implied by this RCP, is unfeasible in the current circumstances [22,23], because it needs a sustained global CO2 mitigation rate of around 3% per year, not a likely prospect, at least in the near future [20].

Out of the remaining three RCPs, the high baseline emission scenario (RCP8.5) and one medium-stabilization scenario (RCP4.5) were selected for the current study. The RCP8.5 was included because it covers the higher end of radiative forcing, as well as the temperature change, and it is also in line with the observed trend of around 3% in the average annual CO2 emission growth rates for 2005–2012 [20,23].

For the medium-stabilization scenarios, both RCP4.5 and RCP6 are equally acceptable, but due to time constraints, and because RCP4.5 shows a better match (≈1.5%) of the trends of the average annual CO2 emission growth rates for the period of 2005–2012 than RCP6 (≈1.0%) [20,23], RCP4.5 was picked along RCP8.5 for the GCM selection procedure.

Additionally, in the current study, only the available GCM runs for the ensemble member *r1p1i1* in the CMIP5 repository [24] are included in the initial list. This is done so as to keep open the possibility of using dynamically downscaled projections (driven by the selected GCMs as boundary conditions) by Regional Climate Models (RCMs), which in most cases have utilized boundary conditions from the ensemble member *r1p1i1* of the GCMs.

In the current study, a total number of 42 available model runs (ensemble member *r1p1i1*) are evaluated for RCP4.5 and of 39 for RCP8.5.
