The version of record of the paper ‘Energy budget constraints on climate response’, published by Nature Geoscience in 2013, is available here, along with its Supplementary Information (non-paywalled). The paper’s authors are Alexander Otto, Friederike E. L. Otto, Olivier Boucher, John Church, Gabi Hegerl, Piers M. Forster, Nathan P. Gillett, Jonathan Gregory, Gregory C. Johnson, Reto Knutti, Nicholas Lewis, Ulrike Lohmann, Jochem Marotzke, Gunnar Myhre, Drew Shindell, Bjorn Stevens and Myles R. Allen.
A non-paywalled copy of the paper is available here.