Posted on Tue, Aug. 27, 2002

Weather Corner
El Niņo, global warming not to blame in disasters

Special to the Mercury News

Bad science makes a return -- once again, everyone's favorite scapegoat is El Niņo, with global warming coming in a close second.

Even though it is barely in its infancy in the equatorial Pacific Ocean, the new El Niņo phenomenon is already being blamed by some for everything from the current U.S. drought to some giant squid that washed up near Los Angeles.

Much of the recent media frenzy was fed by new reports from Great Britain, which pretty much placed the blame on El Niņo for everything but Elvis' death 25 years ago. At the same time, some Europeans are pinning their catastrophic floods this summer on global warming, which they blame on the United States because Bush administration officials renounced the international Kyoto Protocol, which regulates greenhouse gases. All this finger-pointing neglects the fact that seasonal events such as El Niņo and long-term events like global warming do not have an appreciable impact on individual storms, especially so quickly.

The European events followed a story from Southern California that had El Niņo as the cause of warm water along the Southern California coast -- and also being responsible for large squid that washed up on the beach. But a close look at the warm water in the equatorial Pacific characteristic of El Niņo shows that there is no connection between it and warm water 3,000 miles away off Southern California.

The reality is that El Niņo is just now barely discernible in the Pacific Sea Surface Temperature, or SST, readings. At this stage, El Niņo may be a contributing factor in drought conditions currently being experienced in Australia, Indonesia and Southeast Asia, but some of that dryness predated the evolution of the current El Niņo. The drought conditions in large parts of the United States have been ongoing for many months and are not a characteristic of El Niņo, except in the Pacific Northwest, which is not particularly dry.

Elsewhere, the effects of the still-developing El Niņo are negligible. If the forecasts of a weak El Niņo are on track, they should remain minimal in what might best be called an ``El Niņo Lite.'' Historically, these weak El Niņo events have not shown a strong signal toward either wetter or drier conditions in Northern and central California. There is a wet signal, however, for Southern California.

For the latest on El Niņo, see

Q From my experience in the Boston area, the worst time of day for Boston's air pollution was about 9 p.m. as the pollution arrived from New York City after rush hour. Yes, the city's pollution after traveling 200-plus miles had a higher level than local Boston vehicular traffic. Does a similar situation occur in the Bay Area due to Sacramento pollution, or our own Bay Area pollution and the incoming fog currents pushing the pollution back inland? Given that the Central Valley's winds push the air out of the Peninsula while the fog is rolling in, it's not clear what the worst time of day is for pollution. Brian Mellea - Los Altos

A In general, Boston is responsible for most of its own pollution as the prevailing winds over New York tend to carry the Big Apple's bad air out over Long Island and the Atlantic. Also, 200 miles is a long way to transport pollution in just a few hours. However, in both the Boston and New York areas, there is a gradual buildup of pollutants in the air through the work week, and this has been tied to an increased frequency of rain on the weekends.

Our prevailing winds tend to carry Bay Area pollution into the adjacent coastal valleys like Livermore Valley and Coyote Valley. These valleys are also warmer and ``cook'' more of their own photochemical smog. The worst air pollution near the bay is in the early afternoon before the sea breeze picks up. Pollution levels are delayed inland until the sea breeze pushes the bad air to those areas.

Q Why are there several areas (called banana belts) that are relatively free of low clouds along the Northern and central California coast? The areas I'm speaking of include south of Cape Mendocino, Point Arena, Pigeon Point and south of Carmel.  Ken Holmes - Sea Ranch

A Banana belts, or warmer parts of the coast, are protected by geography. The thing that these locales have in common is a physical barrier to the north that has two influences. First, these barriers block the prevailing northwest winds and keep some of the coastal low clouds and fog from spreading into these areas. Second, air flowing up and over these barriers warms and dries out as it descends back to sea level. I would also add Santa Cruz, in the lee of the Santa Cruz Mountains, to your list of such areas.