The Global Cooling Project proposes large scale rainwater harvesting (RWH) in semi-arid tropical countries to increase soil moisture in periods of low rainfall, thus improving vegetation cover and cloud cover. This dossier brings together scientific evidence of critically important impacts of strategic rainwater harvesting (SaRaH) for regional and global climate. It comprises comprehensive peer-reviewed evidence for the beneficial role of strategic/large scale rainwater harvesting in semi-arid tropical countries in: • global cooling • regional cooling • increased regional rainfall and prolonged rainy season This is to be undertaken on a large scale in 4 continents, with a initial priority on West Africa. For full details of the project see the separate document: "The Global Cooling Project - outline". While global cooling may be important and helpful, it is through impact on regional temperature and rainfall the the greatest benefit is likely to accrue to human beings and ecosystems.