IPCC AR4 to AR5

Terminology Unchanged – GCMs – General Circulation Models AR4 – SRES – Special Report on Emissions Scenarios AR5 – SSPs – Shared Socioeconomic Pathways – RCPs – Representative Concentration Pathways – RAPs – Representative Agricultural Pathways

How are these terms related? SSP RCP SRES (A1B, B1, etc.) RAPs IPRs from IMPACT

RCP 2.6 is below anything from AR4 RCP 6 is most similar to A1B RCP 8.5 is higher than anything AR4 RCPs

RCP – Trends

RCP Details DescriptionIA ModelPublication – IA Model RCP8.5Rising radiative forcing pathway leading to 8.5 W/m2 in MESSAGERiahi et al. (2007) Rao & Riahi (2006) RCP6Stabilization without overshoot pathway to 6 W/m2 at stabilization after 2100 AIMFujino et al. (2006) Hijioka et al. (2008) RCP4.5Stabilization without overshoot pathway to 4.5 W/m2 at stabilization after 2100 GCAM (MiniCAM)Smith and Wigley (2006) Clarke et al. (2007) Wise et al. (2009) RCP2.6Peak in radiative forcing at ~ 3 W/m2 before 2100 and decline IMAGEvan Vuuren et al. (2006; 2007)

Climate impacts under RCP GFDL

Climate impacts under RCP HadGem

Climate impacts under RCP IPSL

Climate impacts under RCP MIROC

SSP1 – Low Challenges SSP2 – Intermediate Challenges, business as usual (med-med) SSP3 – High Challenges SSP4 – Adaptation Challenges Dominates SSP5 – Mitigation Challenges Dominates SSPs

SSPs are separated from emissions, but not all SSPs are compatible with all RCPs Combining SSPs with RCPs