Scientists warn of looming water supply crisis 01.15.08 Search

Problems ahead, varying by region

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Radical water cycle changes will be widespread and that past trends can no longer be relied upon when planning future water management

They argue that radical water cycle changes will be widespread and that past trends can no longer be relied upon when planning future water management. "Our best current estimates are that water availability will increase substantially in northern Eurasia, Alaska, Canada and some tropical regions, and decrease substantially in southern Europe, the Middle East, southern Africa and southwestern North America," said lead author Christopher Milly, a research hydrologist with the US Geological Survey.

More frequent droughts can also be expected in drying areas, he added. "Even with aggressive mitigation, continued warming is very likely given the residence time of atmospheric carbon dioxide and the thermal inertia of the Earth system," the authors concluded.

The article says that new models must be used to prepare for floods or droughts, determine the size of water reservoirs and decide how to allocate for residential, industrial and agricultural uses. This is a massive undertaking seeing as annual global investment in water infrastructure is more than 500 billion dollars a year and these are made under outdated assumptions that the water cycle will fluctuate within a relatively narrow historical band. "Historically, looking back at past observations has been a good way to estimate future conditions," Milly said."

But climate change magnifies the possibility that the future will bring droughts or floods you never saw in your old measurements. "Climate change has already resulted in changes to rainfall patterns and river flows and created a greater risk of flooding in some areas, the authors wrote. Rising sea levels will "heighten risk of contamination of coastal freshwater supplies" while a "poleward expansion of the subtropic dry zone" is reducing water runoff levels.

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