Constraints on Ω_m and σ₈ in the base-ΛCDM model from CMB lensing alone (posterior sample points coloured by the value of the Hubble constant in units of km s⁻¹ Mpc⁻¹) using the priors described in the text. Grey bands give corresponding 1σ and 2σ lensing-only constraints using the approximate fit . The joint 68% and 95% constraints from CMB lensing with the addition of BAO data (Beutler et al. 2011; Ross et al. 2015; Alam et al. 2017) are shown as the dashed contours, and the constraint from the Planck CMB power-spectrum data is shown for comparison as the solid contours.