A great deal of research on climate change over the last decade has focused on changes to the hydrologic cycle—the continuous process by which water is circulated throughout the earth and the atmosphere—which naturally impacts water supply. These changes—earlier spring snowmelt, increased evaporation from higher temperatures, and more frequent and intense droughts—are obvious. And the changes are alarming. Water suppliers and large water users simply cannot afford to ignore climate change as they plan for the future.

Many water suppliers have begun to consider how climate will affect their water supplies, whether it is from a lake or river, stored behind a dam, or drawn from underground aquifers. Not as much attention has been paid to the other side of the equation: What will climate change do to water consumption?

Most people familiar with the state of climate change expect that a warmer climate will drive up water demand for landscapes and the inevitable evaporative cooling. Yet there has been little research on this subject and even less practical guidance for water planners and managers.

Two recent research projects have contributed to this emerging field of study, to better predict how climate change will affect future water demand. In 2012, my colleagues and I at the Pacific Institute developed a planning tool focused on the state of California that forecasts water use out to the year 2100. A year later, in 2013, the Water Research Foundation published a nationwide study, “Changes in Water Use under Regional Climate Change Scenarios.”

Both of these groundbreaking studies demonstrated how climate change can help predict future urban water use. We worked closely with climate scientists to translate the output from their models into information on water demand for use by water managers. Our work focused mostly on how temperatures are causing an increase in evaporation and water lost to the atmosphere by plants. In California, as in much of the West, more than half of publicly supplied water is used outdoors. Some of this is used for washing cars or sidewalks, or for filling pools and spas, but most is for landscape irrigation.


http://www.usgbc.org/articles/what-w...-century-usgbc


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