New features for the modeling for AR5 (2013)

Some cool new science add-ins for the modeling running up to AR5.
-Inclusion for the first time of the permafrost melt that is underway.
-Complete integration of the nitrogen cycle.
-Perhaps the most cool feature, Representative Concentration Pathways.
What those are, is answers to 4 "what if" questions. The 4 things are 4 scenarios regarding the overall warming power of human activities. The scenarios are (all running from the model's start time to 2100):

RCP8.5 Emissions rise indefinitely, ghg concentrations reach 1,370 p.p.m.
RCP6.0 Emissions level off, ghg concentrations reach 850 p.p.m.
RPP4.5 Emissions level off, ghg concentrations reach 650 p.p.m.
RCP3.0-PD Emissions level off, ghg concentrations reach 490 p.p.m.

One question I have, is about the "target" aka, the 2 degree "guard rail" concept of not more than 350 p.p.m. in 2050. How does that relate to RCP3.0-PD? If anyone knows, let me know...