Chicago: Climate change has already dramatically altered the water cycle and these changes signal a looming water supply crisis, according to a prominent group of hydrologists and climatologists writing today in Science magazine.

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as annual global investment in water infrastructure is more than 500 billion dollars a year and these are made under outdated assumptions that the water cycle will fluctuate within a relatively narrow historical band.

Source : PTI