Biodiversity loss and climate change are global environmental changes and the seriousness of both for human society and for life on Earth is increasing. The 1992 Earth Summit led to the formation of the Convention on Biological Diversity and the Climate Change Convention, but binding agreements on biodiversity have been relatively limited. Biodiversity loss is relatively easy to communicate and has many advocates. However, its causes are complex and multi-layered, and its consequences are not obvious or widely shared. While few people doubt the importance of wild species and habitats this alone does not seem to provoke the necessary responses. As a result biodiversity continues to decline. I describe work to put a value on lost biodiversity and an economic case for conservation. I conclude that while biodiversity conservation readily attracts public support, the economic arguments need careful attention in order to be both credible and to stimulate appropriate actions.