Global warming could have local impact Global warming could have local impact (February 18, 2005)

Experts expect strain on reservoirs, baylands

By Jon Wiener

With the Kyoto Protocol taking effect this week, few residents would consider global warming a problem for Mountain View.

Wealthy enough to ward off floods or weather storm damage, global warming does not pose quite the same threat here as it might in a place like Bangladesh, where tens of millions of people live in lowlands that could be entirely underwater in the coming decades.

But higher temperatures could lead to water-supply and flooding problems for local residents, and experts say that now is the time to get prepared for those impacts.

"We're already in the midst of seeing the effects of warming, and we're going to have to plan for them," said Mike O'Connor, executive director of the San Francisco Estuary Institute, a monitoring agency funded by income from permits purchased by companies that discharge chemicals into the bay.

A major effect could be on the city's water supply, which is drawn almost exclusively from snow-fed streams. Currently, much of that water is stored in the Sierra snowpack, gradually flowing into reservoirs over the course of months. But as the climate warms and the snow melts earlier, a large portion of that run-off could be wasted if it cannot all be squeezed into reservoirs.

"I think we are already seeing evidence of climate change in California's water -- we're already seeing changes in the timing of run-off," said Peter Gleick, president of the Oakland-based Pacific Institute.

No one really knows whether reservoirs will be able to handle the increase, he said. If they can't, cities like Mountain View will face perennial water shortages during the dry season.

"Water managers aren't prepared for this, and they're not thinking about this," said Gleick.

The Santa Clara Valley Water District, which draws half of its water from Sierra snowmelt, is trying to gather more data about how global warming will affect snowmelt, according to spokesperson Mike DiMarco. The district is also looking at other watershed issues, such as flood control and ecological habitat, he said.

Building levees and other measures to protect bayfront property from rising sea levels could cost about $1.3 billion in present-day dollars, according to a 1990 study that Gleick co-authored.

But higher tides do more than just put pressure on the shore. They also clog up the drain for the city's creeks during winter storms, potentially leading to greater and more frequent floods.

"For the most part, in the South Bay, the issue is fresh water from the hills having a way to get out," said O'Connor.

The Kyoto Protocol is the first major international treaty on climate change. Participating countries, which do not include the United States, agreed to limit their greenhouse gas emissions to pre-1990 levels.

E-mail Jon Wiener at jwiener@mv-voice.com

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