Adapting to climate change in the water sector

from Overseas Development Institute
Published on 18 Mar 2009 View Original
ODI background note

By Alan Nicol and Nanki Kaur

Water is the key medium that links atmospheric temperature rises to changes in human and physical systems.

Climate change will alter the hydrological cycle in many ways. The trigger is the warming of the atmosphere and oceans, which will change major weather systems. This will alter the temporal and spatial patterns of rainfall with consequences for runoff, surface and groundwater storage, river flow regimes and, it is estimated, greater likelihood of extremes - droughts and floods - in different parts of the world.

These changes will, in turn, affect major human livelihood systems, particularly those dependent on direct access to natural assets. Rain-fed agriculture, human settlement patterns and movement, water supplies, sanitation and irrigation will all be affected, leading to changes in human health, wealth and security. On the demand side, as populations grow and move - and as their income levels increase or decrease - their demand for water resources will change, both spatially and temporally.

Taken together, the net effect of these supply and demand-side changes will present major challenges to future management of water resources for human and ecosystem development. Demand management, which aims to regulate withdrawals at sustainable levels through such measures as the promotion of sustainable use, pricing mechanisms, and water saving crop production techniques, will become increasingly important in areas where relative scarcity and competition between sectors is increasing. Supply side management will become a priority where inter-annual resource availability is likely to change significantly and where populations are more vulnerable. Supply side management, in general, involves increasing or augmenting the supply of water resources through increased storage capacity, abstraction from water course, rainwater harvesting and recharge activities and/or introducing incentives for water conservation.

The Intergovernmental Panel on Climate Change (IPCC) Technical Paper on Climate Change and Water states that 'water resource issues have not been adequately addressed in climate change analysis and climate policy formulations. Likewise, in most cases climate change problems have not been dealt with in water resource analysis, management and policy formulation' (Bates et al., 2008). This suggests a gap in the analysis required to understand the full effects of climate change on human and natural systems and, moreover, how policy makers can and should improve future responses to climate change at country, regional and international levels.

This background note outlines the state of existing knowledge and suggests better ways to build successful adaptation approaches into the water sector.