Local and global environmental problems are increasingly demanding our attention, as threats to our quality of life and even our physical survival become more apparent. The environmental agenda has largely been driven by understandable concern for the increasing pressure placed on the natural world by human behaviour. In the forty years since the publication of Rachel Carson’s Silent Spring first drew attention to the consequences of human activity on natural systems, the scale of the problem has grown inexorably. The human population has more than doubled, economic activity has quadrupled and carbon dioxide emissions have increased tenfold. Environmental problems have inexorably broadened in scope from the local to the regional, then the national and finally the global with depletion of the ozone layer, climate change and loss of biodiversity.