John on December 4, 2009 at 11:02 am
Yesterday I noted that the California Energy Commission and Google had collaborated on a new map/video which shows the effect of a 4+ foot sea level rise on San Francisco in the year 2100. I noted that this projection was based on Rahmstorf’s 2007 study and the fact that his study has many detractors.
Today, a tipster sent me a link to this publication by the Army Corps of Engineers. Published July 1, 2009, this paper essentially lays out guidelines for the consideration of Sea Level Rise in the planning for future levies. Here is the Corps’ advice:
Planning studies and engineering designs should consider alternatives that are developed and assessed for the entire range of possible future rates of sea-level change. These alternatives will include structural and nonstructural solutions, or a combination of both. Evaluate alternatives using “low,” “intermediate,” and “high” rates of future sea-level change for both “with” and “without” project conditions. Use the historic rate of sea-level change as the “low” rate. Base “intermediate” and “high” rates on the following:
- Estimate the “intermediate” rate of local mean sea-level change using the modified NRC Curve I and equations 2 and 3 in Appendix B (see Figures B-9 and B-11). Consider both the most recent IPCC projections and modified NRC projections and add those to the local rate of vertical land movement.
- Estimate the “high” rate of local sea-level change using the modified NRC Curve III and equations 2 and 3 in Appendix B (see Figures B-9 and B-11). Consider both the most recent IPCC projections and modified NRC projections and add those to the local rate of vertical land movement. This “high” rate exceeds the upper bounds of IPCC estimates from both 2001 and 2007 to accommodate for the potential rapid loss of ice from Antarctica and Greenland.
Determine how sensitive alternative plans and designs are to these rates of future local mean sea-level change, how this sensitivity affects calculated risk, and what design or operations and maintenance measures should be implemented to minimize adverse consequences while maximizing beneficial effects. Consider sensitivity relative to human health and safety, economic costs and benefits, environmental impacts, and other social effects. Address risks for each alternative and each potential future rate of sea-level change (“low,” “intermediate,” and “high”). For those alternatives sensitive to sea-level change, evaluate the potential timing and cost consequences during the plan formulation process.
Here is a graph from appendix B of the document which shows the low, medium and high sea-level change options out to 2100 (click for full size):
So the Corps notes that the low option (blue line in the graph) is the one that accords with historic sea-level rise data. Both of the other two curves assume that SLR is going to accelerate as a result of global warming.
Now notice that the red line (the “high” option) shows a rise of about 1.5 meters or 4 1/2 feet by 2100. That’s the one that California’s Energy Commission, Google and Governor Schwarzenegger chose to highlight yesterday in the video/map of San Francisco inundated with water.
Schwarzenegger made the unveiling on Treasure Island (in the middle of the San Francisco Bay) precisely because the “high” model shows Treasure Island will be under water by 2100. At the event he said “Within a century, Treasure Island, this place where we are right now, could be totally under water.”
Well, yes, it is “possible.” It’s also possible that one of the other options the “intermediate” or “low” curves will turn out to be the case. If so, Treasure Island will not be under water by 2100. But the Governor didn’t seem interested in presenting those possibilities, even though the Corps of Engineers says they should be considered.
Rather than considering all three possible outcomes and then doing some sort of cost-benefit analysis on them as the Corps recommends, Californians are being presented with only the most extreme possible outcome, one which literally assumes the worst based on some extremely questionable assumptions about global temperatures over the next 100 years.
In short, this was an exercise in hype aimed at the uninformed and those who don’t have time to look into the facts behind the high-tech presentation.
Of course if Google were to graphically illustrate the outcome of the “low” SLR option (the one based on actual historical data instead of climate change computer models) the result would about 18″ of sea-level rise by 2100. I suspect a map of this change would show little if any inundation of San Francisco. But of course no alarming outcome means no carte blanche for government bureaucrats to do things like outlaw television sets based on the harm done to the environment.