The Roiling Sea

Moon over the WPH Lagoon  |  photo by Ric Miller  |  post by Richard Pavek

Sea level is not level at all. Just as the surface of the earth is not flat, the surface of the ocean is not flat. Because the earth rotates to the east and because the ocean responds slowly to the rotation* and the surface of the sea piles up along the continent’s Eastern Seaboard. Therefore, absolute sea level is lower along the West Coast of North America than the East Coast! Sea Level at the Atlantic end of the Panama Canal is about 8 inches higher than at the Pacific end.

Superimposed on this unlevel sea are the moon-driven tides. These tides are long, slow moving waves that move across the oceans in response to the pull of the moon and sun; they progress toward the coastlines where we are aware of them as the regular rise and fall of the sea—the tides. These long tidal waves can be minimal or occasionally immense, as are the huge swells of Mavericks at Pillar Point, near Half Moon Bay.

The great swirls of weather-driven wind moving across the ocean’s surface create hills and valleys in the sea, all the while lifting huge masses of water high into the atmosphere, later dropping them on the sea or land in the form of rain or snow. These hills and valleys in the sea are augmented by the submerged mountains and canyons far below the surface.

El Nino Effects in Northern California

El Nino is a part of a routine climate pattern that occurs when surface temperatures in the tropical Pacific Ocean rise to above-normal levels for an extended period. El Ninos develop in the central and east-central equatorial Pacific. Severe El Ninos develop when high pressure jet streams build up in the western South Pacific and then bring significantly wetter winters to northwest Mexico and the southwest United States, including central and Southern California. The strongest of these develop a chain of storm centers that slowly move to California. When the jet stream in the upper atmosphere swings northward it affects both El Nino’s landfall and persistence.

Climate Change, Melting Ice Caps and the Rising Sea

The frozen North is warming up. On December 30, 2015 the temperature at the North Pole rose above freezing for the first time in recorded history—50 degrees above normal!

Whether or not our current global warming is man-made, the seas—and our tides—are rising several inches a year because the massive Greenland and Antarctic ice sheets are melting at an accelerating rate; the storms produced by the warming oceans have shifted southward and no longer deliver sufficient snow to replace the melted ice.

By 2008 San Francisco Bay’s waters had risen 8 inches since the mid-80s when measurements were first taken. The recent ice melts have added to that.

* The Earth’s speed of rotation is approximately 1037 mph at the Equator. That’s about 518 mph at North Richardson Bay. Fortunately, our atmosphere moves also!