In this International Year of Biodiversity, we should be setting ambitious but realistic targets for biodiversity policy over the next ten years. Those shaped at last month's sixth Trondheim Conference on Biodiversity in Norway will be refined by the Subsidiary Body on Scientific, Technical and Technological Advice in May and at the Conference of the Parties of the Convention on Biological Diversity (CBD) in October.

As participating scientists in the international biodiversity programme DIVERSITAS, we welcome the draft set of 2020 targets proposed by the CBD. But the targets continue to mix the biodiversity we value highly (that is, the conservation agenda) and the biodiversity we urgently need to secure the benefits people derive from fully functioning ecosystems.

To resolve competing demands, these different priorities should be made explicit by categorizing the targets according to their primary motivation. We suggest the use of red targets to stem urgent deleterious biodiversity loss, green targets for conservation priorities and blue targets to secure the long-term benefits from functioning ecosystems.

The CBD should work closely with the science community to develop these targets for changing environments and in the light of new scientific discoveries. The proposed Intergovernmental Platform for Biodiversity and Ecosystem Services (H. Mooney and G. Mace Science 325, 1474; 2009) and the global biodiversity observation system GEO BON (R. J. Scholes et al. Science 321, 1044–1045; 2008) will be valuable tools in this collaboration.