Material World - 17/09/2009

As international negotiations stumble towards a replacement for the Kyoto climate protocol, it is a sobering thought that the greatest reduction in greenhouse gases comes from a completely different treaty. The Montreal Protocol, which came into force 20 years ago to protect the ozone layer, also managed to remove huge quantities heat-trapping CFC gases from the atmosphere. To mark World Ozone Day, Quentin Cooper looks at the lessons from this most successful of environmental treaties. Also, the legacy of crop scientist Norman Borlaug. Quentin hears about the challenges of feeding the world in 2050, and how science can help. And the cup and the cuppa - what determines the taste of tea?