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The Difference a Degree Makes

via SFGate:

Chronicle environment writer Jane Kay and photographer Kat Wade traveled from Alaska to Mexico to see how global warming is changing life along the coast of North America.

Sunday: Polar bears signal changing ice cap in the Arctic.
Today: Subtle seaside transformation in California.
Tuesday: A family sees its way of life threatened in Mexico.

E-mail Jane Kay at jkay@sfchronicle.com

Nature out of sync

Sea life depends on the intricate workings of wind and current, driven by temperatures of ocean and air. Animals depend on the natural timing of seasons to find food. In the past 60 years, as ocean temperatures off the California coast warmed by about 3 degrees, the tiny animals at the base of the food chain declined by 70 percent.

A WARMING WORLD: THE DIFFERENCE A DEGREE MAKES
SEASHORE SEA CHANGE

- Jane Kay, Chronicle Environment Writer
Monday, January 16, 2006

 

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 [excerpt]:

Pacific Grove, Monterey County -- On the edge of the California coast, in the tide pools that tourists can see from Cannery Row, delicate anemones and sea stars are helping to tell the story of a warming world.

At low tide in the dawn light, John Pearse, a retired professor of biology at UC Santa Cruz, kneeled in the water in hip-high waders examining sunburst anemones. He found pink barnacles encrusting rocks, and the hard white shells of worm snails.

Those invertebrates normally are more common in warmer southern waters. But over decades, they have increased in numbers here. Invertebrates that do well in colder water, such as giant green sea anemones and porcelain crabs, have declined. Central California has become more like Southern California.

"Animals are responding to changes in temperature, and the change in temperature is very rapid,'' said Pearse, who began studying the low-tide zone as a graduate student nearly 50 years ago.

Unlike in the Arctic, where floating sea ice and land glaciers dramatically melt before Alaskans' eyes, along the California coast the signs of a changing environment are more subtle.

Those who know where to look can see that a few degrees increase in the temperature of the Pacific and a couple of inches rise in sea level have already changed life in Monterey Bay's fragile tide pools.

While some species will prosper, others may die. The question scientists up and down the coast are pursuing is just how the continued warming of the atmosphere and water may disrupt the ocean's intricate web of life.

In the ocean, the whales, seabirds and fish at the top of the hierarchy depend on lower organisms for food. In the last six decades, as sea water temperatures on the Monterey coast increased about 3 degrees Fahrenheit, scientists measured a 70 percent decline in zooplankton, the tiny animals at the base of the food chain.

What does it matter if a warmer world loses some inedible crabs or sea stars?

"It's hard to predict,'' said George Somero, director of the Hopkins Marine Station, the state's oldest marine laboratory, which looks down on the rocky shore here. "If you remove one species from the ecosystem, there could very well be severe perturbations in the system. In many cases, we can't predict what that means.''

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