Big Facts on Climate Change, Agriculture and Food Security

Demand-side Strategies

• Water pricing, allocation quotas and water rights are effective but underused tools to manage demand for water (IWMI 2013a).
• Rivers, lakes, aquifers and the like cut across geographical and political boundaries, so any efforts to manage these resources involve decisions and actions by a range of stakeholders, each with their own interests and constituencies. Dealing with this will require stakeholder-focused cost-benefit analysis (Lunduka et al. 2013; Chambwera et al. 2012).
• Demand for water from both agricultural and non-agricultural sectors (e.g. municipal uses and industry) can improve resilience if managed carefully. The key to climate-change adaptation is integrated and system-wide approaches to water management (UN-Water 2010).
• One good adaptation option is to reuse wastewater for irrigation, instead of disposing of it untreated in surface water. This is especially true for rice crops. Using wastewater in this way not only helps adaptation to climate change, but can also contribute to food security in areas with rapid growing populations (Trinh et al. 2013).
• Improving wastewater management can increase returns and reduce risks of flood damage and pest attack, but the effectiveness of re-using wastewater as an adaptation strategy will depend on local farming practices, market conditions, crop varieties and cost-effective treatment options (Kurian et al. 2013).
• The amount of water consumed in lowland rice production can be reduced by alternate wetting and drying–alternately flooding rice fields and allowing them to dry out. This increases adaptive capacity under climate change and also reduces greenhouse gas emissions (IRRI 2009).

Supply-side Strategies

• Storing water can help reduce variability in supplies. Planned and managed correctly, it also increases water security, agricultural productivity and adaptive capacity. However, all water storage options are also potentially vulnerable to the impacts of climate change (McCartney and Smakhtin 2010).
• There is considerable uncertainty about how climate change will affect water supplies in future. Dealing with this uncertainty requires development of flexible storage systems, possibly combining a variety of types (IWMI 2009).
• Wetlands can store excess water during the wet season and release it slowly as river levels fall. They also improve the quality of polluted floodwater, prevent saline intrusion, absorb storm surges and provide alternative sources of income (Wetlands International 2013).
• Irrigating crops using groundwater reduces dependence on rainfed agriculture and provides a buffer against climate variability (MacDonald et al. 2012). The main benefits of groundwater storage systems for climate adaptation are that little or no water is lost to evaporation and that supplies do not vary markedly from season to season (McCartney and Smakhtin 2010). Approaches to boosting groundwater supplies include farmer-managed groundwater systems (FAO 2011) and groundwater banking, which uses discharge from hydropower dams to recharge aquifers (IWMI 2013a).
• Rainwater harvesting can be used to capture excess rainfall during the rainy season and store it for future use. In doing so, farmers can increase the area they can irrigate, grow crops in the dry season, support livestock and even recharge groundwater. The water can be allowed to soak into the soil (in situ harvesting) or channelled to storage structures such as ponds, tanks or reservoirs (ex situ harvesting) (IWMI n.d.).
• Another source of additional water is desalination. Water can be desalinated either (1) by boiling the water and condensing the water vapour (very energy intensive) or (2) using ultra-thin, semipermeable membranes (much less energy intensive). Currently, for 60% of desalinated water is produced using the membrane system (IWMI, 2013b).
• Water productivity can be increased by 15%–20% in smallholder rainfed agriculture. Small investments in supplemental irrigation (providing 1,000 cubic metres of extra water per hectare per season) in combination with improved soil, nutrient and crop management can more than double water productivity and yields in small-scale rainfed agriculture (Rockstrom et al. 2007).
• The amount water used for irrigation can be reduced through a range of technical and management practices, including drip and sprinkle irrigation, more precise application practices (level basins, surge irrigation), canal lining or delivery through pipes, reduced allocations of water to farmers and pricing to influence demand. Many of these practices also increase yields (Molden et al. 2007 p. 295)