Upper left: Planck measurements of the lensing power spectrum compared to the ΛCDM mean prediction and 68% confidence interval (dashed lines) for models fit to Planck+WP+highL (see text). The eight bandpowers are those used in the Planck lensing likelihood; they are renormalized, along with their errors, to account for the small differences between the lensed in the best-fit model and the fiducial model used throughout this paper. The error bars are the ± 1σ errors from the diagonal of the covariance matrix. The colour coding shows how varies with the optical depth τ across samples from the ΛCDM posterior distribution. Upper right: as upper-left but using only the temperature power spectrum from Planck. Lower left: as upper-left panel but in models with spatial curvature. The colour coding is for Ω_K. Lower right: as upper-left but in models with three massive neutrinos (of equal mass). The colour coding is for the summed neutrino mass ∑ m_ν.