The link between land use and the climate is complex. First, land cover--as shaped by land use practices--affects the global concentration of greenhouse gases. Second, while land use change is an important driver of climate change, a changing climate can lead to changes in land use and land cover. For example, farmers might shift from their customary crops to crops that will have higher economic return under changing climatic conditions. Higher temperatures affect mountain snowpack and vegetation cover as well as water needed for irrigation. The understanding of the interactions between climate and land use change is improving but continued scientific investigation is needed.