Externalities are at the heart of the contribution by van den Bergh (2010) and will be treated in the next section. His contribution nevertheless contains some general remarks on sustainability economics that will be noted here. van den Bergh (2010) correctly remarks that
Baumgärtner and Quaas (2010a) have failed to specify sustainability policy. In his view, integrated sustainability policy could serve as a transition device. He also argues for downscaling sustainability assessments, so that they are performed at the regional level.