To address the surprising lack of research in the area of environmental migration, this paper reviews the existing literature and proposes two basic, two region, and general equilibrium models: a closed economy and a small open economy where migration occurs between regions. The models show that migration increases welfare in the rural region, characterized by a tragedy of the commons production function, but does not affect welfare in the region with a constant returns to scale production function. The paper also provides an economic definition of an environmental refugee in the respect of an environmental migrant.