Global warming or freak year?
2005-08-02 13:34
San Francisco - Marine biologists are seeing mysterious and disturbing things along the Pacific Coast this year: higher water temperatures, plummeting catches of fish, lots of dead birds and very little plankton.
Is this just one freak year? Or is this global warming?
Few scientists are willing to blame global warming, yet few are willing to rule it out.
"There are strange things happening, but we don't really understand how all the pieces fit together," said Jane Lubchenco, a zoologist and climate change expert at Oregon State University.
"It's hard to say whether any single event is just an anomaly or a real indication of something serious happening."
Scientists say things could very well swing back to normal next year. But if the phenomenon proves to be long-lasting, the consequences could be serious.
This much is known: From California to British Columbia, unusual weather patterns have disrupted the marine ecosystem.
Normally, in the spring and summer, winds blow south along the Pacific Coast and push warmer surface waters away from shore. That allows colder, nutrient-rich water to well up from the bottom of the sea and feed microscopic plants called phytoplankton.
Phytoplankton are then eaten by zooplankton, tiny marine animals that include shrimp-like crustaceans called krill. Zooplankton, in turn, are eaten by seabirds and by fish and marine mammals ranging from sardines to whales.
'Relatively sudden'
But this year, the winds have been unusually weak, failing to generate much upwelling and reducing the amount of phytoplankton.
Off Oregon, for example, the waters near the shore are 3 to 4 Celsius warmer than normal and have yielded about one-fourth the usual amount of phytoplankton, said Bill Peterson, an oceanographer.
"The bottom has fallen out of the coastal food chain, and there's just not enough food out there," said Julia Parrish, a seabird ecologist at the University of Washington in Seattle.
Seabirds are clearly distressed. On the Farallon Islands west of San Francisco, researchers noted a steep decrease in nesting cormorants and a 90% drop in Cassin's auklets.
On Washington state's Tatoosh Island, common murres - a species so sensitive to disruptions that scientists consider it a harbinger of ecological change - started breeding nearly a month late.
Researchers have also reported a sharp increase in dead birds washing up in California, Oregon and Washington.
Fish appear to be feeling the effects, too. NOAA found a 20% to 30% drop in juvenile salmon off the coasts of Oregon, Washington and British Columbia.
Scientists have seen some of these strange happenings before, during El Nino years, but the West Coast has not had El Nino conditions this year.
As for the possibility that this is being caused by global warming, scientists are not so sure, since climate change is believed to be a gradual process, and what is happening this year is relatively sudden.
- AP