IPCC AR4 Scenarios (2007) [Alan]

 A1: rapid economic growth; pop. peak mid-century; rapid introduction of efficient technologies.
A1F  Fossil fuel intensive,
A1T  Non fossil-fuel intensive,
A1B  Balanced
A2: Business As Usual – heterogeneous world; high pop growth; slow economic growth; slow technological change;
B1: as A1 in population but more rapid economic change to service/information economy;
B2: intermediate pop growth; local economic & social solutions; environmental sustainability focus.

IPCC AR5 Representative [Atmospheric Carbon] Concentration Pathways] (2013-12014) assessed as change by 2100 from Pre-Industrial conditions.

Current warming impact: 2.75 w/m²

RCP 2.6 Low Emissions:  Peak in radiative forcing at ~ 3 W/m² before 2100 and decline ; so-called “peak” scenario: its radiative forcing level first reaches a value around 3.1 W/m2 mid-century, returning to 2.6 W/m2 by 2100.  Greenhouse gas emissions (and indirectly emissions of air pollutants) are reduced substantially over time.

RCP 4.5 Medium Emissions:  4.5 W/m² at stabilization after 2100. A stabilization scenario where total radiative forcing is stabilized before 2100 by employment of a range of technologies and strategies for reducing greenhouse gas emissions

RCP 6.0: 6 High Emissions W/m² at stabilization after 2100. A stabilization scenario where total radiative forcing is stabilized after 2100 without overshoot by employment of a range of technologies and strategies for reducing greenhouse gas emissions.

RCP 8.5 Highest Emissions – Business As Usual: 8.5 W/m² in 2100. Increasing greenhouse gas emissions over time leading to high greenhouse gas concentration levels.