The most challenging topic in the area of EDE is, to my point of view, the understanding of the various issues related to biodiversity and their modeling. We do not know much about the reasons why we would want to prevent ecosystem and species losses, but we suspect that preventing large-scale loss is indeed a tremendously important task we should undertake rapidly. We need tools to help us evaluate the costs of these losses and the benefits of preventing them, and to provide guiding principles for environmental policy.