Climate Change and the Water Cycle Richard Harding Centre for Ecology and Hydrology

Drivers of Global Change: Increasing population Increasing water consumption Land cover/use change Increasing greenhouse gases

Stern Review (2006 )

Water Consumption - after Shiklomanov Consumption, km 3 /year Agriculture Industry Municipal needs Reservoir Total Assessment Forecast

Areas of physical and economic water scarcity (IWMI, 2006)

 We represent the earth by a grid of squares, typically of length 150 km or smaller.  The atmosphere and oceans are divided into vertical slices of varying depths. To predict the future we need the climate models

FIGURE SPM-6. Relative changes in precipitation (in percent) for the period 2090–2099, relative to1980–1999. Values are multi-model averages based on the SRES A1B scenario for December to February (left) and June to August (right). White areas are where less than 66% of the models agree in the sign of the change and stippled areas are where more than 90% of the models agree in the sign of the change. IPCC 2007

Smoothed annual anomalies for precipitation (%) over land from 1900 to 2005; other regions are dominated by variability. Land precipitation is changing significantly over broad areas Increases Decreases

Climate change scenarios – the changing seasons UK winter Wetter: Up 10% by 2020s, up to 30% by 2080s Drier: 20% by 2020s, up to 50% by 2080s UK summer

Climate change scenarios – changing extremes

Percentage change in flows for the 20- year return period Climate change scenarios – impact on flows

10km Glacier melt in the Himalayas

SAGARMATHA: Snow and Glacier Aspects of Water Resources Management in the Himalaya %change in decadal mean flow for Ganges from regional climate model output (RCM2)

The WATCH Integrated Project:  25 European partners: hydrology, climate and resource scientists  13m euros of effort  International programme  research, workshops, training, dissemination

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