What balance do I strike between the worries and the hopes about surpassingly important water and irrigation? The worries clearly remove hope of brute expansion of irrigated area or even of irrigation's strong-arming urban needs for water.
These worries do not, however, cloud hope of using our heads to produce more food from each liter of irrigation water. The worries, in fact, can induce technology. Globally, water is abundant and can be delivered to dry places if energy grows cheaper. Disparate efficiencies of delivering water to the soil show opportunities for engineering. And removing any limitation such as fertility, genes, or pests, improves water use efficiency. Even more water itself improves efficiency, making irrigation to supplement Nature's free rain particularly efficient. Although water likely leads the list of factors curbing our ability to save land for Nature, it need not stop us.