Water

Observed warming over several decades has been linked to changes in the large-scale hydrological cycle such as: increasing atmospheric water vapour content; changing precipitation patterns, reduced snow cover and widespread melting of ice and changes in soil moisture and runoff. Thus, semi-arid and arid areas are particularly vulnerable as water supplies are projected to decline in the course of the century.

Reduced water availability during warm and dry periods and disruptions in monsoon patterns are severely affecting rain-fed agricultural production as well as water supply for domestic and industrial purposes. Prolonged droughts could also result in regional vegetation die-off.

As a result, poor rural, especially the subsistence farmers in the arid and semi-arid tropics and Asia and Africa, will be greatly affected. In addition, water salinisation is expected to be a major problem in small islands suffering from coastal sea water intrusion.

A unique risk in mountainous areas is glacial lake outburst floods leading to the sudden discharge of large volumes of water and debris. This has caused catastrophic downstream flooding and serious damage to life, property, forests, farms, and infrastructure.

Floods have been the most reported natural disaster events in Africa, Asia and Europe and have affected more people across the globe than all other natural disasters. In Bangladesh, three extreme floods have occurred in the last two decades, and in 1998 about 70% of the country’s area was inundated.

Higher water temperatures and increased precipitation intensity also exacerbate many forms of water pollution, with impacts on ecosystems, human health, water system reliability and operating costs. According to Water Aid, diarrhoeal diseases caused by unsafe water and poor sanitation, such as cholera, typhoid and dysentery, are common across the developing world - killing 5,000 children every single day.

Water is recognised to be key to the achievement of many of the Millennium Development Goals. In Asia, one in five people, or 700 million, do not have access to safe drinking water and half the region's population lacking access to basic sanitation. As it is becoming scarcer in certain places, the availability of this strategic resource in the globe is a major social and economic concern. Water is an important element in many political conflicts and increased violence has been reported in recent times due to decreased water availability especially during summers the tropical countries.

Climate change also affects the functioning and operation of existing water infrastructure – including hydropower, structural flood defences, drainage and irrigation systems – as well as water management practices. Thus, irrigation and agricultural systems have to adapt to climate change through water conservation practices in farming and animal husbandry and through techniques like drip/micro irrigation. Farmers can adopt indigenous practices like varying the crop mix, altering the crop calendars and growing crops that require very little water.

Practices like grey water reuse which includes utilising waste water generated in the kitchen and bathroom for flush-toilets and for watering kitchen gardens and rainwater harvesting are successful ways of water conservation.

A water secure world will need better information and stronger institutions, as well as investment in infrastructure – small and large scale – to store and transport water. It will require balancing equity, environmental and economic priorities and appropriate attention to both natural and man-made storage options. It will require actions and innovations at all levels: in projects, communities, nations, river basins and globally.

Water resources management should therefore be an early focus for adaptation to climate change and should be based on a participatory approach, involving users, planners and policy-makers at all levels.