Climate Change and Water Availability – North American Context Linda Mortsch Adaptation and Impacts Research Division Expert Round Table on National and Global Water Issues Toronto, Ontario November 8, 2008

Projected changes in climate … Increase in temperature –SNOW changes to RAIN –More evapotranspiration –Less ice cover –Less storage in snow cover and glaciers –Less groundwater recharge? Changes in precipitation –North - more precipitation especially winter –Southwest - less precipitation especially summer

Past climate may not be a reliable guide for water resources planning and management… Challenging assumption of stationarity of climate and hydrologic data because of climate change Changes in distribution, amount, timing and quality of water supply More extreme conditions –Heavy precipitation events, droughts, floods, low flow Changes beyond institutional experience

Challenges in managing multiple interests on Columbia River … Balancing complex, competing demands – flood control, hydropower, navigation, endangered species, municipal uses, irrigation Current and projected needs over-commit supplies Little change in annual flow but more winter and spring flows and lower summer and fall flows Ability of managers to meet reliability goals - decline

Multiple, interacting and cumulative effects … Source: Lemmen & Warren, 2003

“Mainstreaming” adaptation –Incorporating climate change information in infrastructure planning and design, and water resources management policies and practices Overcoming barriers –Expand reservoirs - legal and environmental issues –Desalinization – high energy demand –Wastewater recycling – ensuring no risk to public health, high cost of advanced treatment and infrastructure Developing adaptive capacity –access to technology, education, information, skills, infrastructure and management capabilities The challenges for adaptation …

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