Water, climate change: recipe for trouble?

• Author: Jean, Grace V.
• Position: INSIDE SCIENCE + TECHNOLOGY

As the Navy likes to remind us, water covers 70 percent of our planet and enables global commerce. Military strategists also caution that future wars will be fought over access to waterways and even over drinking-water supplies. And yet, we still lack a comprehensive understanding of how the world's water possibly could be affected by the phenomenon of climate change.

Many parts of the world are experiencing shifts in temperature and precipitation, which in turn affect wildlife and natural resources. As a result, scientists internationally are sounding a collective call to study how the changing climate is influencing that cycle and, in particular, how water behaves in the ecosystem.

To begin investigating the dispersal of water from mountaintops, through landscapes and into rivers and oceans, researchers at the University of Arizona are planning to conduct long-term experiments at a glass-enclosed facility in the southwestern desert. Once dubbed a failed science experiment for space colonization, the Biosphere 2 is being renovated this summer to accommodate the ecohydrology research,

"Our goal is to make a predictive tool for how water behaves in our environment," says Travis Huxman, director of Biosphere 2 and an associate professor of ecology and evolutionary biology at the University of Arizona, which took over management of the 3.14-acre facility last July.

[ILLUSTRATION OMITTED]

Scientists currently use statistical models to make predictions, such as how rainfall will influence river behavior, "But the reality is, you can't extend those statistical tools into an uncertain future," he says,

The elements of global climate change--rising temperatures and changes in carbon dioxide concentrations, precipitation and nitrogen deposition--all affect water behavior within an ecosystem. For exam pie, when there is a higher concentration of carbon dioxide in the atmosphere, plants tend to absorb more water.

But because it is difficult to predict how ecosystems will respond to all those varying elements at the same time, the scientists are constructing specific landscapes to help them isolate the different factors.

Inside the intensive agriculture biome of the Biosphere 2, scientists are building three "hillslopes" in separate bays that measure 30 meters long and 18 meters wide. These hillslopes consist of specially shaped basins, called zero-order catchments, which slope at a 12-degree angle and converge in a gully. When filled with soil, the...