Let (M, ω) be a compact symplectic 4-manifold with a compatible almost complex structure J. The problem of finding a
J-compatible symplectic form with prescribed volume form is an almost-K¨ahler analogue of Yau’s theorem and is connected to a
programme in symplectic topology proposed by Donaldson. We call the corresponding equation for the symplectic form the Calabi-
Yau equation. Solutions are unique in their cohomology class. It is shown in this paper that a solution to this equation exists if the
Nijenhuis tensor is small in a certain sense. Without this assumption, it is shown that the problem of existence can be reduced to obtaining a C0 bound on a scalar potential function.