  We analyze the source of inter-model scatter in the surface temperature
response to quadrupling CO2 in two sets of GCM simulations from the Tropical
Rain Belts with an Annual cycle and a Continent Model Intercomparison Project
(TRACMIP; Voigt et al, 2016). TRACMIP provides simulations of idealized
climates that allow for studying the fundamental dynamics of tropical rainfall
and its response to climate change. One configuration is an aquaplanet
atmosphere (i.e., with zonally-symmetric boundary conditions) coupled to a slab
ocean (AquaCTL and Aqua4x). The other includes an equatorial continent
represented by a thin slab ocean with increased surface albedo and decreased
evaporation (LandCTL and Land4x).
