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El Niño Warms Coast

It's official: El Niño, a disruption of the ocean-atmosphere system that periodically wreaks havoc on the global climate, is back-and experts are comparing it to the milestone El Niño of 1982-83, which brought the wettest winter of the century to Northern California and caused more than $10 billion in U.S. crop losses.

During an El Niño, warm water from the tropical Pacific flows east and north and normal trade winds disappear or change direction. The conditions usually bring heavier-than-normal precipitation to the southern U.S. and dry conditions to the Northwest. According to Bill Mork, a climatologist with the Department of Water Resources, ocean water temperatures in the Pacific were two to four degrees (Celsius) higher than normal in July, the greatest anomalies observed since 1982.

Although some El Niño years-notably 1976-77, the driest year of the century-can bring drought to Northern California, the strongest El Niños tend to be wet ones, says Mork.

"This El Niño started early and is expected to peak in November," says Mork. "Precipitation is likely to be above normal, and may start as early as September, but to say more than that would be premature."

Regardless of its impact on the weather, El Niño is likely to affect the Estuary and its inhabitants. According to Dan Howard of the Gulf of the Farallones National Marine Sanctuary, El Niño's warm waters prevent the normal upwelling of nutrient-rich cold water."Without nutrients the phytoplankton populations don't expand, and the result is reduced productivity at all levels of the marine food web," he says.

Among the species that could be affected are ocean-going Estuary dwellers such as salmon. Holly Ryan of the U.S. Geological Survey says that as El Niño pushes water east it can actually raise water levels inside the Bay. However, the effects of the rise are unclear. "More seawater in the Bay could potentially increase the salinity," says Ryan. "But the flip side is that El Niños tend to have higher rainfall and greater freshwater flows, which may offset the effect on salinity."

Amid the predictions and speculations Water Resources' Mork advises a measure of calm. "It may not come to anything," he says. "There have been cases where El Niño conditions developed early and then died early."

Contact: Bill Mork (916) 574-2614

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