More than 2,400 scientists and policymakers convened in Stockholm last month for the 2008 World Water Week summit. This year's summit was focused on sanitation access, although a variety of interdisciplinary research was presented for discussion.

Inadequate sanitation is a known cause of infectious diseases and death in the developing world. In response, improvement in sustainable access to safe drinking water and sanitation became part of the UN Millennium Development Goals.

Mother Nature's calendar has been showing increasingly less resemblance to the seasonal patterns of the past, with tangible effects on both humans and the natural environment. Pollen-releasing grasses, shrubs and trees have started to appear earlier, expanding the hay fever season. Drought, forest fires and invasive alien species have caused serious damage to some of the world's most vulnerable ecosystems.

The hazy skies over the 2008 Summer Olympics have placed Beijing's air quality at the top of news headlines for more than a month. However, outdoor air pollution, whether in the form of visible haze or invisible ozone and carbon monoxide, is a problem in nearly every country in the world.

Many vulnerable species are facing reduced numbers because the adaptations that have served them for thousands of years make them unable to survive small changes in temperature or precipitation. When faced with climate change and other threats to their habitat, some species may not be able to relocate quickly enough to save them from extinction. A new technique called assisted colonization may prove to be an innovative solution.