This collection of papers was presented at a conference on linkages between climate change, water, conflict and migration, held in September 2011 at The Hague, in the Netherlands, where the discussion focused on: capacity building and resilience in climate hotspots; conflict prevention; and a legal framework to protect environmental migrants.

The publication includes a conference summary and a background document providing an overview of how climate change, water stress and environmental problems are increasingly seen as major threats to human security. Also included are papers that explore connections between these issues from the perspective of vulnerability; put forward a research and capacity-building agenda for climate-induced migrations; and review current literature, evidence and implications for policymaking on the environment, climate change and human displacement.

This paper looks at how climate change could affect the rate of phenological development — biological events related to climate, such as flowering — and rainfall patterns during the growing season. The authors suggest that these changes may result in mismatch between water demand by crops and water availability from rainfall.

The paper describes a project that combines a new analysis of meteorological data with previously published data on climatic changes to assess the expected consequences of this mismatch for food security.

The authors illustrate how understanding how key crops might be affected by climate change in the Asia-Pacific region can help farmers, community workers and policymakers to prepare and adapt. Strategies include timing of planting, managing rainwater resources, use of new varieties, alternate crops and shifts in geographic distribution of crops.

This journal article investigates the significance of drought and other water-related constraints in South Asia compared with other limitations to the production of four major food crops — wheat, rice, sorghum and chickpea — in five South Asian farming systems.

The study was based on a survey of 330 'expert informants'. It indicates that water shortages and constraints such as high-cost irrigation or flooding of low-lying fields contribute to no more than 30 per cent of current yield gaps in major food crops. Other constraints contribute the most to yield losses, particularly soil infertility and poor management of fertiliser, weeds, pests and diseases. The respondents suggested interventions to address these constraints and improve food security, which include biotechnology and improvements in soil fertility.

This article, written by scientists in Niger and the United States, assesses the suitability of solar-powered irrigation for improving food security in rural regions of West Africa. The authors describe an irrigation system that combines drip irrigation with a photovoltaic solar-powered water pump, and test its efficacy and impact through household surveys and field data. They find that solar-powered drip irrigation is cost-effective and significantly boosts household incomes and nutritional intake.

This commentary, by South African scientists Thembela Hillie and Mbhuti Hlophe, examines nanoscience's potential to solve the technical challenges associated with removing pollutants from water. The authors describe a range of nano-based water treatment technologies already in the marketplace and discuss how nanofiltration membranes can be used in low-cost methods to produce safe drinking water. They highlight a case study in South Africa where such membranes were used to treat brackish groundwater.

The authors emphasise the importance of technology transfer in getting nano-based solutions to the countries that need them, arguing that direct transfer does not often work. Rather, what developing countries need are approaches that combine technology transfer with technology adaptation and adoption — involving local stakeholders in establishing water treatment devices and developing local capacity to use them.