There are widespread fears that global environmental change will cause problems, which may differentially affect rich and poor countries. There is a need for all nations to act together to face global environmental challenges. Large populations with wide eco-footprints are vulnerable to global changes and will be difficult to cater for if there are serious environmental or socio-economic upsets. In the past a major disaster, like an Indian famine, affected only a few million people – now even single urban conglomerations like Mexico City contain over 20 million. Before the present day most countries were largely self-sufficient in food and energy – today most depend on long supply chains. Developing countries import grain and manufactured goods from developed countries, and developed countries buy food and fuel from developing countries – the world’s people are interdependent.