IPCC AR 4 to AR 5 Terminology Unchanged

IPCC AR 4 to AR 5

Terminology • Unchanged – GCMs – General Circulation Models • AR 4 – SRES – Special Report on Emissions Scenarios • AR 5 – SSPs – Shared Socioeconomic Pathways – RCPs – Representative Concentration Pathways – RAPs – Representative Agricultural Pathways

How are these terms related? SRES (A 1 B, • SSP B 1, etc. ) • RCP IPRs from • RAPs IMPACT

RCPs • RCP 2. 6 is below anything from AR 4 • RCP 6 is most similar to A 1 B • RCP 8. 5 is higher than anything AR 4

RCP – Trends

RCP Details Description RCP 8. 5 RCP 6 RCP 4. 5 RCP 2. 6 IA Model Rising radiative forcing pathway leading to 8. 5 W/m 2 in 2100. Stabilization without overshoot pathway to 6 W/m 2 at stabilization after 2100 Stabilization without overshoot pathway to 4. 5 W/m 2 at stabilization after 2100 Peak in radiative forcing at ~ 3 W/m 2 before 2100 and decline Publication – IA Model MESSAGE Riahi et al. (2007) Rao & Riahi (2006) AIM Fujino et al. (2006) Hijioka et al. (2008) GCAM (Mini. CAM) Smith and Wigley (2006) Clarke et al. (2007) Wise et al. (2009) IMAGE van Vuuren et al. (2006; 2007)

Climate impacts under RCP 8. 5 - GFDL

Climate impacts under RCP 8. 5 - Had. Gem

Climate impacts under RCP 8. 5 - IPSL

Climate impacts under RCP 8. 5 - MIROC

SSPs • SSP 1 – Low Challenges • SSP 2 – Intermediate Challenges, business as usual (med-med) • SSP 3 – High Challenges • SSP 4 – Adaptation Challenges Dominates • SSP 5 – Mitigation Challenges Dominates

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