Coyote Gulch

Saturday, September 22, 2007

Global warming: The Earth is a beautifully complex system

Here's a short article about climate change and its effect on rivers in the west from The Aspen Daily News "reg". They write:

Global warming could mean both more droughts and more flooding to the Roaring Fork and other Western rivers, and in just decades it could bring dramatic consequences to local farmers, anglers and fish, a University of Colorado climate researcher said. "(Climate researchers) can sometimes talk out of both sides of our mouths," said Kenneth Strzepek, a University of Colorado professor who has studied the possible impacts of warming temperatures on waters in Colorado around the world. "It's getting wetter. It's getting drier. But the thing we know is that the extremes are changing." That could mean more frequent flooding in rivers around the world, including the Roaring Fork, Strzepek said, and in Western snow-fed rivers, earlier runoffs could leave the riverbeds running dry by summer's end.

Strzepek discussed the predictions at the Given Institute on Thursday in a presentation organized by the Roaring Fork Conservancy. He dubbed the presentation a "sequel" to one he delivered in Aspen 15 years earlier. Since then, he said, scientists' models on the impact on the world's water systems have improved greatly. Arid climates are expected to become even drier, Strzepek said, and areas that flood may see worse flooding, sometimes with devastating consequences, particularly in the developing world. "The poor will suffer the most, who have the least capability of adapting and dealing with that," he said. Globally, heavy floods, the so-called "100-year" floods, are predicted to increase. Models for 100-year floods in Boston show them doubling in frequency by 2050, Strzepek said, and doubling again by 2100. In India's Ganges-Brahmaputra Basin, where a 2004 flood took over 1,200 lives, heavy "100-year floods" could come every nine years, he said...

It's not clear how warming temperatures will affect Colorado precipitation, Strzepek said. The Southwestern United States is expected to become drier, meaning more demands on the Colorado River. But northern states could see more precipitation, and Colorado is caught in the middle. But models show snowmelt coming sooner, runoff peaking earlier and river levels dropping faster. That's bad for trout, which could see dangerously low water levels and temperatures reaching fatal levels, Strzepek said. It's also bad for rafting companies that could see shorter seasons, and for ranchers who will likely need more irrigation water. By 2070, he said, runoff could peak a month early, putting water levels out of synch with growing seasons. That could leave even some senior water rights holders out of luck if their rights are timed, he said. Low water levels could also affect ski areas' ability to use water for snowmaking, he said.
"2008 pres"
7:35:15 AM