Climate change and water: technical paper IV

Observational records and climate projections provide abundant evidence that freshwater resources
are vulnerable and have the potential to be strongly impacted by climate change, with wide-ranging
consequences for human societies and ecosystems. 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, intensity and extremes; reduced snow cover and widespread melting of ice; and changes in soil moisture and runoff. Precipitation changes show substantial spatial and inter-decadal variability.

This paper seeks to provide a comprehensive overview of the impact of climate change on water resources. It covers:

• Observed and projected changes in climate as they relate to water
• Linking climate change and water resources: impacts and responses
• Climate change and water resources in systems and sectors
• Analyzing regional aspects of climate change and water resources
• Climate change mitigation measures and water
• Implications for policy and sustainable development
• Gaps in knowledge and suggestions for further work.