3/ also, it’s the carbon cycle that links emissions and concentrations (forcing), and climate sensitivity that links forcing and response (forcing is just the partial derivative of the radiation change to the GHG). But imo climate science should distance itself from all the storyline stuff.
It’s truly astonishing to see how comprehensively the US government is tearing down every part of the system that has made it up until now a world-leading power in science, research, and technological development. The entire world will suffer from this wanton destruction.
1/ I disagree a bit, but likely circle back to same conclusion as Katharine. SSPs are socioeconomic stories, not forcing scenarios. They become forcing trajectories when run through IAMs that integrate a bunch of assumptions with climate/energy/land systems to generate emissions scenarios.
5/ the criticism of RCP8.5 is that we couldn’t tap into the implied coal (or wouldn’ turn geologic resources into viable reserves). That’s fine but all of this is beside the point for climate. I completely agree with Katharine hats there’s uncertainty in the actual physical system to bracket ranges
2/ even saying RCPs are not emission scenarios is a bit too strong, each canonical RCP does come bundled w specific emissions trajectories from the IAM that generated it, tho there is not a unique pathway that reaches the forcing level. I’m not sure how much this matters for actual climate modeling.
4/ nobody’s storyline would make sense if done around WW2, 1970s oil shocks, fall of USSR, 1929 crash, China’s one-child policy, advent of the internet, etc. We’re also quite blind to geopolitical shocks but capture gradual divergence between worlds.