This is the common perception of the meaning of Hansen’s 1988 scenarios.
–A: Increase of CO2 emissions of 1.5% per year
–B: fixed increase CO2 emissions after the year 2000
–C: No increase in CO2 emissions after the year 2000
But that isn’t accurate. What Hansen actually wrote was
- Scenario A means steadily increasing annual emissions.
- Scenario B doesn’t make any sense, but possibly means constant annual emissions at a level lower than 1988.
- Scenario C means essentially zero emissions after the year 2000 i.e. “net climate forcing ceases to increase after the year 2000.”
So where are we according to GISS? Below the zero emissions scenario C.
Temperatures are lower than Hansen forecast they would be if humans disappeared off the planet twelve years ago.