We address long time behavior of solutions to the 2D Boussinesq equations with zero diffusivity in the cases of the torus, R 2 , and on a bounded domain with Lions or Dirichlet boundary conditions. In all the cases, we obtain bounds on the long time behavior for the norms of the velocity and the vorticity. In particular, we obtain that the norm (u, ρ) H 2 ×H 1 is bounded by a single exponential, improving earlier bounds.Here, u is the velocity satisfying the 2D Navier-Stokes equations [CF, DG, FMT, R, T1, T2, T3] driven by ρ, which represents the density or temperature of the fluid, depending on the physical context. Also, e 2 = (0, 1) is the unit vector in the vertical direction.Recently, there has been a lot of progress made on the existence, uniqueness, and persistence of regularity, mostly in the case of positive viscosity and vanishing diffusivity, considered here, while the same question with both vanishing viscosity and diffusivity is an important open problem. The initial results on the global existence in the regularity class have been obtained by Hou and Li [HL], who proved the global existence and persistence in the class H s × H s−1 for integer s ≥ 3. Independently, Chae [C] considered the class H s × H s and proved the global persistence in H 3 × H 3 . The class H s × H s−1 has subsequently been studied in the case of a bounded domain, where Larios et al proved in [LLT] the global existence and uniqueness for s = 1 and then by Hu et al, who proved in [HKZ1] the persistence