Tropical agriculturalisation: scenarios, their environmental impacts and the role of climate change in determining water-for-food, locally and along supply chains

The aim of this paper is to examine the potential for continued agriculturalisation in the tropics and the potential impacts of this on tropical natural capital and ecosystem services. Concurrently we examine the extent to which projected climate change will drive changes in the water available to support food security, locally and along supply chains through impacts on rainfall in key agricultural areas and the implications of climate change for continued agriculturalisation. We make use of global spatial datasets to examine the tropical distribution of current cropland and pasture and the distribution of the remaining non-agricultural 'wild' areas in relation to their suitability for cropland and pasture. We thus identify the most suitable/likely areas for further agriculturalisation in the tropics under increased domestic and export demand. We then examine the potential risks to natural capital and ecosystem services of such agriculturalisation and highlight critical areas for careful agricultural expansion. We examine the non-agricultural lands with greatest suitability for pasture and cropland and highlight the key countries capable of contributing to significant increases in global food production. Further, we examine trends in recent land use change and project these forward to understand the parts of those countries most imminently likely to go under the plough and consider implications for natural capital and ecosystem services. We then examine ensemble climate change projections for the current agricultural areas in Latin America, to better understand likely impacts of tropical climate change on sustained agricultural suitability in these areas, with implications for further extensification. Finally, we use the COMTRADE database to examine the flows of "embedded rainfall" supporting key agricultural commodities from the tropics. This is in order to understand the extent to which climate change will amplify or diminish the potential for virtual water flows between the tropics and the rest of the world. Results indicate rapid and necessary agriculturalisation in the tropics under business as usual, which brings considerable threats to the remaining natural capital and ecosystem services in these areas. At the same time we expect climate change - at least for South America - to bring greater water availability and the possibility of increased productivity in current agricultural areas. If true, this could offset some of the demand for expensive and risky extensification of agriculture, and encourage a more focused intensification.