Coping with water scarcity

Climate change will require human adaptation. Water harvesting can mitigate predicted water scarcity.

By Lisa Shipek

from the April 5, 2007 edition

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TUCSON, ARIZ. - As climate change becomes the No. 1 environmental issue around the world, it presents a new framework for evaluating – and gives greater urgency to – a host of other sensitive environmental issues, such as loss of biodiversity, desertification, natural disasters, and water scarcity.

Even as policymakers debate ways to limit global warming by decreasing the emission of greenhouse gases, there is a growing sense that no level of human response can completely forestall the effects of climate change in coming decades. That's why adaptation is so critical.

Tomorrow, the United Nations' Intergovernmental Panel on Climate Change will release the second volume of its Fourth Assessment Report on global warming, titled "Impact, Adaptation, and Vulnerability." An expected key finding will examine predicted water shortages – for 1.1 billion to 3.2 billion people, according to Reuters – and the options available to cope with them.

That report comes on the heels of last month's World Water Day, which focused this year on coping with water scarcity.

Water scarcity is not just a problem in arid regions; even in the lush tropics of Costa Rica, communities experience water scarcity due to deforestation and intensive agriculture. Water quickly becomes scarce when communities, industry, agriculture, and natural ecosystems all depend on the same source. That competition is expected to intensify as climate change affects precipitation patterns around the globe, potentially depleting natural water reservoirs.

That's the bad news. The good news is that proven strategies already exist to manage this kind of water scarcity.

In the southwestern United States, climate research shows that temperatures are expected to increase. Predictions vary as to whether the Southwest will become wetter or drier. Despite the uncertainty of the amount of precipitation change, a greater variability in precipitation is expected, resulting in a higher frequency of extreme events such as droughts, high-intensity storms, and flooding.

Up to 75 percent of the water supplies for the Western United States come from snowpack. As glaciers and snowpack decrease with warming temperatures, this natural water reservoir will be depleted, threatening Western water supplies. A similar pattern is predicted in other mountainous areas, such as the Andes and the Himalayas – an area that supplies water to 1 billion people.

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