SAN FRANCISCO The California Current system has experienced significant changes during the past decade, resulting in dramatic variations in the ecosystem characterized by shifts in phytoplankton production, expanding hypoxic zones, and the collapse of marine food webs off the western coast of the United States. These changes, driven by new wind patterns, are consistent with predictive models of global climate change, scientists said this week at the annual meeting of the American Association for the Advancement of Science.
But the researchers stopped short of saying that climate change was the definitive cause.
"This coming year will be important," said Jack Barth, a professor of oceanic and atmospheric sciences at Oregon State University. "If the persistent wind patterns of the last few years continue through 2007, it might be enough to tip the scales in favor of climate change as a cause for these extreme variations in our West Coast marine environment.
"Our research has shown there is a 'wobble' in the Jet Stream that in some years has tended to overpower the more historic day-to-day variations in climate in favor of these two- to three-week wind patterns that influence upwelling and ultimately, ocean production."
Eight scientists, including five with ties to Oregon State University, are part of a AAAS symposium, "Predicting the Unpredictable: Marine Die-Offs along the West Coast." This week, they outlined how marine ecosystems are responding to widely different climate-driven variables, beginning in 1997-98 with one of the most powerful El Nino episodes on record.
During that El Nio, ocean waters off the West Coast grew warmer, nutrients decreased, biological production was reduced, and species from zooplankton to salmon disappeared, were drastically reduced or moved from their typical habitats. The El Nio capped what had been a series of years through the 1990s characterized by warm waters and weak upwelling.