Contents for this issue: Coral reef ecosystems: monitoring climate change Question and answer Extended writing: ten tips for quality answers What happens to your rubbish? The geography of waste Food security in Detroit: a case study NEA ideas?Measuring surface roughness in natural systems Geographical ideas Interdependence Centrepiece Can London become a National Park? Geographical skills Using photos as evidence in your NEA: presenting and interpreting images Wetlands in drylands: understanding dynamic environments Global development update International trade: changing approaches Making connections Glaciation, climate change and tectonic hazards Measuring development: can we improve on GDP? Index to Volume 21 The big picture Destroying the sense of place in Venice