Rangelands have the potential to be a sink for significant amounts of carbon, especially if they are restored to their ecological potential. Rangeland restoration would have a major impact on global climates since the world's drylands (excluding the hyperarid regions) cover 5.2 X 109 ha. The huge cost range rehabilitation could be provided via privately funded carbon offset programmes and special efforts to sequester C in the world's drylands. The challenge for rangeland scientists is to devise ways to raise biomass levels to trap and store C in the long-term. (CAB Abstract)