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West Coast Sea Levels Stable, Scripps Says That May End

Tuesday, May 3, 2011
posted by Bradley J. Fikes

According to global warming climate change theory, sea levels are supposed to be rising at an accelerating rate across the planet. However, measurements in San Diego and other coastal areas of the United States recorded by the National Oceanic and Atmospheric Administration show no such trend. San Diego’s sea level trend has remained stable for a century.

San Diego's sea level is increasing at a rate of 2.06 millimeters a year, or 0.68 feet (8.16 inches) per century, according to the National Oceanic and Atmospheric Administration (NOAA). Click to see NOAA Web page.

San Diego's sea level is increasing at a rate of 2.06 millimeters a year, or 0.68 feet (8.16 inches) per century, according to the National Oceanic and Atmospheric Administration (NOAA). Click to see NOAA Web page.

That news doesn’t appear to have reached politicians and other policymakers yet, who generally accept the catastrophic scenarios of accelerating sea level rise. Policymakers are reluctant to challenge the statements of renowned scientists and other experts. However, unlike air temperature trends and tree ring proxies, sea level observations are relatively easy to understand.

Now, scientists from Scripps Institution of Oceanography have addressed the discrepancy with a study that gives an explanation and suggests that the acceleration in sea level rise is impending. This post below, which I originally wrote on my North County Times blog, explains the high-stakes implications for global warming theory.

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San Diego and other areas of the West Coast may soon experience rising sea levels, which have remained steady for the last three decades, according to a new study from Scripps Institution of Oceanography.

The study’s lead author is Peter Bromirski, an SIO associate project scientist.

The study addresses a conundrum: Global warming theory predicts that as temperatures rise, the global sea level will rise at an accelerating rate. However, this has not been observed to take place on the West Coast (and many other parts of the globe, I might add).

Scripps researcher Bromirski, the lead author of a study now in press in the Journal of Geophysical Research-Oceans, has an explanation for the discrepancy between global warming theory of sea level rise and the observed data on the West Coast. Bromirski says the Pacific Decadal Oscillation is responsible.

The PDO has brought colder water to the surface in the eastern Pacific near the coast of North America, inhibiting a rise in sea level, Bromirski says. But there’s signs of a change in the current to a negative or “cold” phase, in which the upwelling of colder water changes to sinking, warmer water. With more warm water on the surface, Bromirski says, the sea level will rise faster.

Dire projections for San Diego took a full page in the report's glossy executive summary

Dire projections for San Diego took a full page in the report's glossy executive summary

Scenarios of accelerating sea level rise in San Diego are part of an alarming 2008 report prepared by scientists working with the San Diego Foundation. The report, which gave climate scenarios out to 2050, predicted more disasters and damage as sea levels rose. The report’s glossy executive summary included a graph indicating the sea level would rise faster beginning in 2000.

The San Diego Foundation report is supposed to be an authoritative guide by scientists to help politicians and other policymakers understand the threat of man-made global warming to San Diego, and what to do about it. The chart below, from the report’s glossy executive summary (meant for politicians and reporters who don’t read the full report), looks unambiguous.

Chart published on Page 6 (Page 8 of the PDF) showing a projected sea level rise of 12 to 18 inches off the coast of San Diego by 2050 because of global warming.

However, a decade’s worth of observational data since 2000 then fails to show any trend toward any acceleration in sea level rise in San Diego.

There’s a couple of anomalies in the San Diego Foundation chart above that policymakers should examine. One is that the observed sea level trend appears to curve slightly upwards. Place a ruler or other straight edge across the blue line and you’ll see the curve. This upward curve subtly makes it easier for the eye to interpret the projected data as the intensification of an already existing curve.

The other anomaly is that the chart, if taken as being true to scale, indicates that sea level off of San Diego has risen by 6 inches between 1900 and 2000. But the NOAA rate of increase is 8.16 inches. Assuming the NOAA numbers are correct, the San Diego Foundation report’s chart has been truncated by more than 2 inches, with a slower rise in the earlier years.

The details of projected sea level rises are laid out in the 2008 report itself, beginning on Page 27 in Chapter 3: Climate Change Scenarios. On Page 28 is a more detailed map of these trends as they relate to global sea levels, showing observed trends and six scenarios with projected data from 2000 to 2050.

Back to the NOAA numbers of a 2.06 millimeter sea level rise off of San Diego . If current trends continue, San Diego sea level will rise from 2000 to 2050 by 103 millimeters, about 4.08 inches. The San Diego Foundation report’s scenario of a 12- to 18-inch rise by 2050 is at least three times as fast as the observed data indicates for the 2000-2010 decade.

The question for policymakers who rely on the San Diego Foundation report is whether they can continue to trust its scenario for sea level rises, when 20 percent of the period it covers fails to meet the observed data. Or to put it another way, how many years does this discrepancy have to go on before policymakers and scientists decide the scenario is not reliable?

If the Scripps study is correct and a change in the PDO coincides with an accelerating rise of sea levels off the West Coast, it will be a significant advancement in ocean science. If not, an essential assumption of global warming theory may be invalidated.

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(DISCLAIMER: This is my view, and not necessarily that of my employer, the North County Times).

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