Let X be a geodesic metric space with H 1 .X / uniformly generated. If X has asymptotic dimension one then X is quasi-isometric to an unbounded tree. As a corollary, we show that the asymptotic dimension of the curve graph of a compact, oriented surface with genus g 2 and one boundary component is at least two. 51F99; 20F69, 54F45, 57M50