REDWOOD CITY, Calif.—A 1,400-acre swath of salt flats along the western edge of San Francisco Bay has become the latest site for a development dispute that promises to become increasingly common in coastal U.S. cities: Whether new waterside growth makes sense when sea levels are rising.

Agribusiness giant Cargill, which owns the Redwood City site, has made salt in San Francisco Bay for decades. Cargill has downsized in recent years, selling 16,500 acres of salt ponds in the area–60 percent of its local operations–to the state and federal government in 2002 for $243 million in cash and tax credits. But it held on to the 1,400-acre site near Redwood City that the company believes is suitable for building.

Several years ago Cargill hired Arizona development company DMB to identify future uses for the site, which is separated from downtown Redwood City by busy Highway 101. DMB has proposed Redwood City Saltworks, a planned community with 8,000 to 12,000 low-rise housing units. It includes new schools and retail stores, sports parks and open space along the bay and mass transit links connecting the development with regional bus, train and ferry lines. "This project is the poster child for an integrated, walkable community" said DMB vice president David Smith.

Opponents have other priorities. A long list of conservation groups, neighboring cities, and local government agencies has endorsed restoring the salt flats to their original state: tidal marshes, which filter bay water, provide habitat for fish and birds, and buffer shoreline communities against flooding by soaking up storm surges.

Redwood City is proceeding with a state-mandated environmental impact review, which could produce a decision sometime in 2011. The study will tackle issues including impacts on traffic, air quality, and water supplies. But a longer-term question that will be unavoidable in the official review is whether building the project would reduce climate change impacts or make them worse.

These choices aren't unique to San Francisco. Officials in New York, Boston, Seattle, and other coastal cities are brainstorming ideas for flood-proofing urban areas, from raising roads to building giant sea gates. So far, however, Orrin Pilkey, professor emeritus of geology at Duke University, sees little action to limit new waterside growth.

"Historically coastal states haven't been serious about limiting shoreline development," said Pilkey, a longtime critic of building in flood-prone areas. Given current projections for sea-level rise, he supports barring construction of high-rise buildings and major infrastructure in vulnerable areas.

"Why increase the cost of preserving cities in the future when we know what's going to happen in less than a century? Our barrier islands [in North Carolina] are going to be un-developable within 40 to 60 years, dikes or no dikes," Pilkey argued.

Timothy Beatley, a professor at the University of Virginia's School of Architecture and author of Planning for Coastal Resilience (Island Press, 2009), has identified a few small cities and counties across the country that are actively steering growth out of flood plains, but says that larger cities are just starting to consider that idea.

In San Francisco the Bay Conservation and Development Commission, known as BCDC, regulates dredging and filling in the Bay and all development within 100 feet of the shoreline; BCDC has proposed identifying low-lying areas where abandoning new development may be more cost-effective than protecting it, but doesn't have jurisdiction to enforce such a policy now.

"Building in vulnerable locations will involve significant public costs in the not-too distant future," Beatley said. "It may make sense to protect some places, but we're going to have to gracefully retreat from others."

Making salt is a simple process: Water flows through a series of shallow ponds, thickening into increasingly saline brine, until salt solidifies and falls out of solution. Fully-saturated brine moves from "pickle ponds" to crystallizer beds, where it dries and is scraped up by giant harvesting machines. Other ponds hold bittern, a highly saline waste solution colored red by salt-loving bacteria. Cargill's Redwood City tract includes crystallizer beds, pickle ponds, and bittern storage ponds.

20 Comments

1. 1. sparcboy 10:06 AM 9/21/10

   Interesting article in light of all the money being spent rebuilding New Orleans, which is built on river delta deposits that are resulting in subsidence that cannot be stopped.
   
   Humans really are an interesting species.

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2. 2. Sisko 11:17 AM 9/21/10

   This article is yet another example of Scientific American inappropriately attempting to keep the frenzy going over the issue of global warming. The core of the actual discussion was whether land formally used as salt flats should be converted to be used for marsh lands or housing and shopping. Scientific American brings up the issue of sea level rise when it had nothing to do with the decision being made.
   
   Yes, sea levels will rise. Over a 500 M year basis, sea levels are currently very near their all time lows. Does anyone believe that sea levels will not rise over time???? If you do, you are not looking at history, or are mentally challenged.

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3. 3. ruspert 12:28 PM 9/21/10

   The salt flats should not be developed as the sea will reclaim it. and who with any intelligence would purchase land that is so low lying anyhow, and those that would would look for taxpayer money to save their investments, not very look ahead thinking. New Orleans,La is an example.

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4. 4. Chris G 01:40 PM 9/21/10

   Sisko,
   It's pretty straight forward that in a warming world, the balance point of ice on land will shift downward, and less ice on land means more water in the sea.
   
   Once again, here is a primer on sea level and how it is changing.
   
   http://en.wikipedia.org/wiki/Current_sea_level_rise
   
   Besides, it sounds like you are saying that sea levels will rise regardless of climate change; so, we shouldn't consider rising sea levels when deciding how to use low lying coast land. What?
   
   

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5. 5. Ralf123 in reply to Sisko 01:42 PM 9/21/10

   The problem is not sea level rise over millions of years, it is sea level rise over decades.
   But hey, what are 5 orders of magnitude between friends?

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6. 6. vendicar9 02:04 PM 9/21/10

   "sea levels are currently very near their all time lows." Capt. Sisko
   
   
   Isn't it amazing, the non stop stream of lies that emanate from the lips of warming denialists.
   
   The following graphic illustrates Sisko's latest deceit quite nicely.
   
   http://oceanexplorer.noaa.gov/explorations/09newworld/background/occupation/media/post_glacial.html

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7. 7. Sisko 02:33 PM 9/21/10

   Chris G & vendicar. I have not lied. What I have done is honestly reviewed the data. When you review the earth's sea levels over 500m years, we are currently at near the all time lows for sea level.....That is simply a fact that you try to hide by looking at questionable short term data.
   Read the chart for yourself.
   http://en.wikipedia.org/wiki/Sea-level_curve Isn't looking at 500 m years of data more honest than what you are doing???
   
   The choice to build or not build on a property is an economic one. The cost of propecting a piece of property from rising tides/sea level is pretty easy to estimate.

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8. 8. Chris G 03:14 PM 9/21/10

   Honest? How honest is it to pretend that the sea levels hundreds of millions of years ago, when the solar output was different, the composition of the atmosphere was different, and the layout of the continents was different, are in any way a good indication of what we should expect for sea levels in the present day?

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9. 9. Chris G 03:23 PM 9/21/10

   "...questionable short term data."
   
   Well, we are talking about human land use, and I am talking about sea levels over the last several thousand years. Considering how quickly the human use of land changes, I believe that thousands of years is probably not too "short term" of a context. Nor are changes that take place over decades too 'long term' to worry about.

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10. 10. Sisko 03:58 PM 9/21/10

    Chris-- But you do agree that for 95% of earth's history that sea levels have been substantially higher than they are today??? Since we agree on that, doesn't it seem pretty logical that today's sea level is unlikely to be maintained regardless of human actions???

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11. 11. Chris G 04:35 PM 9/21/10

    Sisko,
    Let's say my period of concern is from now and extends about seven generations into the future. Within that time period, there is no reason to believe that anything other than human influences will cause sea level to change in any significant way.

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12. 12. Trent1492 04:39 PM 9/21/10

    " Since we agree on that, doesn't it seem pretty logical that today's sea level is unlikely to be maintained regardless of human actions???"
    
    No. This is like saying that since natural forest fires have occurred in the past and will in the future that we should have no concern about human induced forest fires. That is deeply stupid.
    
    You make no distinction between the actions of blind nature and sentient beings. Having a rock roll of a cliff and killing someone is a tragedy. Having a rock being thrown off a cliff with carelessness and the disregard of its tragic consequences is criminal. That you can not distinguish between the two is itself sad.
    
    That you think that because sea level has been higher in the past and will be higher in the distant future means that we have nothing to worry about over the next century is class A idiocy.
    

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13. 13. vendicar9 in reply to Sisko 05:32 PM 9/21/10

    "I have not lied. What I have done is honestly reviewed the data." - Captian Sisko
    
    And now you have lied twice in this thread as the following link clearly shows.
    
    http://oceanexplorer.noaa.gov/explorations/09newworld/background/occupation/media/post_glacial.html
    
    We have all noted that you are a chronic liar.

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14. 14. karrijean in reply to Sisko 05:49 PM 9/21/10

    I agree with the logic, that sea levels will rise. To save time and money do the proposed salt ponds and marshes. Practical and smart.

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15. 15. karrijean in reply to Chris G 05:56 PM 9/21/10

    Sea levels will rise do you understand me now!!!

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16. 16. jtdwyer 07:05 PM 9/21/10

    Well done, all! San Franciscans should simply argue incessantly until the land in question is under water, diluting future arguments.

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17. 17. Sisko 07:21 PM 9/21/10

    LOL @ vendicar-- she/he is really a fool generally worth addressing. She put out stupid comments and ignores facts.
    
    @trent--so you would spend lots of resources to attempt to maintain the oceans at their current levels although 500 million years of history has demonstrated that the seas will rise regardless of man's actions. You propose to implement these actions in one country (the United States) knowing that CO2 emission growth in the rest of the world will make a marginal reduction in the US meaningless to the total amount of CO2 released worlwide. You would propose to do this even knowing that naturally released CO2 from soils do vary over time and the data does not support the conclusion that all CO2 growth is due to humans? Certainly seems like bad economics for the USA- but that seems typical of you logic.

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18. 18. Trent1492 in reply to Sisko 08:04 PM 9/21/10

    @Sisko,
    
    "trent--so you would spend lots of resources to attempt to maintain the oceans at their current levels although 500 million years of history has demonstrated that the seas will rise regardless of man's actions."
    
    Logic Fail:Because the ocean has risen in the past without human action does not mean that human actions can not make the ocean rise now.
    
    This is like saying that since forest fires have occurred in the past before humans discovered fire that arson is impossible.
    Most adults realize that the same phenomena can have different causes. Why can't you?
    
    "You propose to implement these actions in one country (the United States) knowing that CO2 emission growth in the rest of the world will make a marginal reduction in the US meaningless to the total amount of CO2 released worlwide."
    
    Keep on flailing at those false targets I am sure you will convince some gullible rube. Just be careful not to get straw in your eye.
    
    "You would propose to do this even knowing that naturally released CO2 from soils do vary over time and the data does not support the conclusion that all CO2 growth is due to humans?"
    
    Oh? Do tell. Since we know that how to distinguish between the two and you just explicitly acknowledged that ability. Can you reconcile that ability of making the distinction of emission source with your denial that humanity has not increased CO2 levels by 40%?
    
    What I want to know is how do you know?
    
    
    

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19. 19. jonryker 12:29 AM 9/24/10

    They shouldn't....it isn't going to happen until after the next glaciation ends....

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20. 20. Trent1492 02:33 AM 9/24/10

    "They shouldn't....it isn't going to happen until after the next glaciation ends...."
    
    It already is.
    
    

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