Global view on present-day effective temperatures for a number of Uranus (a) and Neptune (b) evolution models of different TBL thicknesses Δm and thermal conductivity factors. Models with T_eff ~ observed T_eff are shown in white, those in red tones are too hot, and those in blue tones are too cold. The models employ a composition of Z_2,water = 1 in theinner mantle, except those shown as diamonds – near the panel bottoms and in the white halo in (b) – which are calibrated to reproduce the observed R_P. The background colour serves as rough guide to the eye. The grey area marks space where no data is available.