"Get your facts first, and then you can distort them as much as you please." (Mark Twain)

Wednesday, July 13, 2005

Between a (Warm) Rock And a (Toasty) Hard Place 

For those who may be unfamiliar with the geography of my home town, realize that the entire city of Seattle occupies a relatively narrow band of real estate between Lake Washington on the east and Puget Sound on the west. Just two days ago, we learned that Lake Washington is in trouble:
For decades, Lake Washington -- the second-largest natural lake in the state -- was the region's toilet bowl. Billions of gallons of sewage were flushed into it. The foul flow didn't stop until the late 1960s, when local scientists had documented the environmental damage beneath the surface.

Now that same research, which continues today, is helping expose a new threat that isn't so easily averted.

No longer limited to glaciers melting in the Arctic, imperiled islands in the Pacific or even slushy ski slopes in the Cascades, evidence of global warming is turning up in Seattle's back yard.

Scientists from the University of Washington, tribes and state and federal agencies are documenting how the lake is changing in slight but potentially profound ways. The entire ecosystem is at risk: from zooplankton to prized salmon that use the lake as a summer home before heading upstream to spawn.

People can be affected, too. Climate change may be contributing to algal blooms, including a toxic variety that can trigger health warnings and beach closures.

Between late spring and fall, the average temperature in the lake's 30-foot-deep top layer has climbed by more than 2 1/2 degrees Fahrenheit compared with readings taken four decades ago. The lake's overall average temperature has increased by 1 degree.

"It's only 1 degree, but it has huge effects," said UW researcher Monika Winder, who has published research on the warming trend.

And today we learn that the view to the west is just as ominous:
Oceanic plankton have largely disappeared from the waters off Northern California, Oregon and Washington, mystifying scientists, stressing fisheries and causing widespread seabird mortality.

The phenomenon could have long-term implications if it continues: a general decline in near-shore oceanic life, with far fewer fish, birds and marine mammals. No one is certain how long the condition will last. But even a short duration could severely affect seabird populations because of drastically reduced nesting success, scientists say.

The plankton disappearance is caused by a slackening of what is known as "upwelling:" the seasonal movement of cold, nutrient-rich offshore water into areas near shore.

This cold water sustains vast quantities of phytoplankton and zooplankton, which are the basis of the marine food web. During periods of vigorous upwelling and consequent plankton "blooms," everything from salmon to blue whales fattens and thrives on the continental shelf of the West Coast.

The larger fish and baleen whales eat mostly krill: free-floating, shrimp- like crustaceans ranging from one to two inches, the upper size limit of the zooplankton realm.

When the water is cold, krill swarm off the Northern California coast by the tens of thousands of tons. Now that they are largely absent, fisheries and wildlife are feeling the effects.

No wonder I'm feeling a bit hot under the collar.




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