In the southwestern United States, where years of drought are leading water managers to consider drastic water-provision measures such as desalination and cloud seeding, entrepreneurs have suggested reviving a water-saving technique that was tried and abandoned half a century ago. They propose to stretch dwindling water supplies by slowing down evaporation from reservoirs by means of a surface barrier of cheap, non-toxic, biodegradable chemicals just one molecule thick — two-millionths of a millimetre.

Natural disasters have enormous impacts on human society, especially on the development of the economy. To support decision making in mitigation and adaption to natural disasters, assessment of economic impacts is fundamental and of great significance.

Rising temperatures and lessening fresh water supplies are threatening agricultural productivity and have motivated efforts to improve plant water use and drought tolerance. During water deficit, plants produce elevated levels of abscisic acid (ABA), which improves water consumption and stress tolerance by controlling guard cell aperture and other protective responses1, 2. One attractive strategy for controlling water use is to develop compounds that activate ABA receptors, but agonists approved for use have yet to be developed.

The world food crisis in 2008 highlighted the susceptibility of the global food system to price shocks. Here we use annual staple food production and trade data from 1992–2009 to analyse the changing properties of the global food system. Over the 18 year study period, we show that the global food system is relatively homogeneous (85% of countries have low or marginal food self-sufficiency) and increases in complexity, with the number of global wheat and rice trade connections doubling and trade flows increasing by 42 and 90%, respectively.