Management of marine resources for sustainable development needs local capacity for science, particularly in the Pacific region.

Policymakers need better information about the regional impact of climate change on water supplies, and on ways of adapting to it.

Nanotechnology holds huge potential for supplying clean water to the world's poor, but many challenges must be overcome to realise it.

The political effect on the United States of its failure to anticipate Hurricane Katrina's full impact will hopefully generate a more considered attitude to the threat of climate change.

Walter Reid, Robert Watson and Harold Mooney defend the term 'ecosystem services' as an essential way of describing to policymakers the importance of the benefits that people receive from ecosystems.

With floods and torrential rains hitting many parts of the world, it is important to remember that the world as a whole faces an increasing shortage of usable water. Increasing the effectiveness with which water is used must become a top priority.

Providing adequate supplies of clean drinking water may not be the most exciting challenge facing scientists working in developing countries. But it is certainly one of the most pressing — and, potentially, the most rewarding.