The fourth order Ginzburg-Landau model is a microscopic model for the diffusion of particles on a surface relaxing to equilibrium. In my talk I will discusss how the evolution of the surface, on the macroscopic scale, given by a fourth order nonlinear evolution equation, emerges as a scaling limit of the particle dynamics. Since the model is of non-gradient type a major step in the computation of the limit is finding the right decomposition of the Hilbert space of "closed functions".