Calif. Dials Up Sea Level Alarm

The graph displays three projections of mean sea level at San Francisco CA. Tihe tidal gauge trend adds 0.2 meters (0.7 feet) by 2100. California Ocean Protection Council (COPC) has issued 2018 guidance on sea level rise along California coastline.  COPC takes IPCC models as gospel truth and projects future sea levels accordingly.  The orange line represents COPC Medium-High risk aversion and produces 1.75 meters (5.7 feet) rise by 2100.  The red line represents COPC Extremely High risk avoidance (worst case) resulting in 3.1 meters (10.2 feet) rise by 2100.

In SF Examiner is this article San Francisco studies impacts of sea level rise as state projections double Excerpts below with my bolds.

In the wake of the city’s losing lawsuit against Big Oil companies, new model projections are going for more scary numbers.

Sea level rise projections from the state Ocean Protection Council were increased earlier this year from a maximum of 66 inches to as high as 122 inches by 2100. That projection includes both sea level rise, which will account for 11 to 24 inches by 2050, and coastal erosion and shoreline flooding.

Planning Department Director John Rahaim said at a Planning Commission hearing Thursday that certain areas of The City will likely see “routine flooding” by 2030.

“Some of the numbers… are in big ranges and there’s this tendency to think of sea level rise as so far in the future that it’s hard to get people’s attention,” Rahaim said. “There are things that are happening in the short term that we really have to start thinking about. It’s not something we can put off to the next generation.”

The commission was briefed Thursday on the progress of efforts to curb the impacts of inundated shorelines since the publication of the 2016 Sea Level Rise Action Plan, which directed city agencies to assess the impacts of sea level rise on San Francisco.

State projections for how high the ocean could rise this century have as much as doubled, giving new urgency to efforts to plan for mitigation efforts, San Francisco planning officials said this week. Sea level rise projections from the state Ocean Protection Council were increased earlier this year from a maximum of 66 inches to as high as 122 inches by 2100. (Kevin N. Hume/S.F. Examiner)

“We have been working with our public infrastructure agencies to really understand, ‘What does this mean for MUNI? What does this mean for our Public Utilities Commission, for our parks?” Maggie Wenger, an adaption planner with the department. “And then what does it mean if those systems face impacts, for the people who live here, work here and come to visit.”

Preliminary findings suggest that between 17 and 84 miles of streets, 242 to 704 acres of open space, 335 acres to 1,203 acres of public land and 2 to 20 schools will be affected by flooding between 2030 and 2100.

The assessment found that roughly 6 percent of land area along San Francisco’s coastal areas is vulnerable to sea level rise.

“Not all areas in this zone are equally vulnerable,” said Wenger, adding that some are likely to see flooding impacts “in the next decades, others in the next century.”

Along with the assessment, The City is currently rolling out a its Port Seawall Earthquake Safety program and has adopted the Islais Creek Southeast/Southeast Mobility Adaptation strategy which focuses on design solutions to strengthening the area and improving the resilience of transportation assets.

A more than $400 million bond proposal to repair San Francisco’s seawall will go before San Francisco voters in November.

Here is the 2018 update document on State of California Sea-Level Rise Guidance

Table 1 is  Projected Sea-Level Rise (in feet) for San Francisco
Probabilistic projections for the height of sea-level rise shown below, along with the H++ scenario
(depicted in blue in the far right column), as seen in the Rising Seas Report. The H++ projection is
a single scenario and does not have an associated likelihood of occurrence as do the probabilistic
projections. Probabilistic projections are with respect to a baseline of the year 2000, or more
specifically the average relative sea level over 1991 – 2009. High emissions represents RCP 8.5;
low emissions represents RCP 2.6. Recommended projections for use in low, medium-high and
extreme risk aversion decisions are outlined in blue boxes below.

Summary

Note that the Medium High projection adds 5 feet on top of the tidal gauge trend of 0.7 feet, a multiple of  8 times greater based upon climate models.  Note also the comment that actual sea level rise may be only on the order of 1 or 2 feet, with erosion on top.

By all means repair the sea wall to resist an additional foot or two.  But the rest of it is coming from Puff the Magic Dragon.

via Science Matters

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July 27, 2018 at 10:05AM

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