Sir

In 2002 the World Summit on Sustainable Development assigned to the Convention on Biological Diversity (CBD) a target for 2010 of significantly reducing the rate of biodiversity loss. If we hope to chart positive trends in biodiversity conservation, then cities must now make a pivotal contribution.

For the first time in history, there are now more people living in cities than in rural areas; cities are likely to become larger, and the number of cities will increase. However, their contribution to the achievement of the CBD's objectives is difficult to measure today. There are tested environmental sustainability and performance indices for countries, but none is applicable to cities. There is therefore an urgent need to compute an aggregate of several indicators of biodiversity conservation for cities.

To enable cities to evaluate their biodiversity conservation efforts better, Singapore proposed that a self-assessment evaluation tool be developed (http://tinyurl.com/q9aj75). This will take the form of an index, devised by the secretariat of the CBD and the Global Partnership on Cities and Biodiversity, and will allow city officials to evaluate their efforts and help them to improve their management of biodiversity.

The index is being designed to be simple, scientifically credible, fair and objective. It focuses on three key components in cities: their indigenous biodiversity; the ecosystem services this provides; and the governance and management of this biodiversity. Balancing a robust number of indicators with manageability led to 26 indicators. Our task-force manual on the computation of the Singapore Index on Cities' Biodiversity will be posted on the CBD website (http://tinyurl.com/lpmwtb).

Most universities are based in cities, so we invite scientists to contribute to this global effort by helping to collect relevant data for the computation of this index. The partnership then aims to table the index for adoption at the 10th meeting of the Conference of the Parties to the CBD in Nagoya, Japan, in October 2010. Data can be e-mailed to L. C.