No longer an abstract future threat, rising sea levels caused by global warming are now a harsh reality that all of us must face — including those concerned with the future of San Francisco Bay and those only concerned with developing the land around it.

Over the last century, sea levels rose about seven inches at the Golden Gate and could rise another two to three feet by 2100, threatening shoreline cities with flooding. The alarming rise in sea level due to global warming threatens the health of the San Francisco Bay Area — our fish, wildlife and Bay Area communities.

The Wisdom of Re-establishing Wetlands
One practical and natural response to the projected rise in sea level is to re-establish 100,000 acres of healthy wetlands all around the Bay. This number is the goal of the San Francisco Bay Habitat Goals Report, a decade-old consensus scientific blueprint for a healthy Bay.

Wetlands play a critical role in the health of the Bay. Wetlands filter water, provide habitat and recreation, and improve the economy and our quality of life. Because tidal salt marshes provide natural flood control, significant wetland restoration is a cost-effective way to help reduce the impact on developed shoreline areas when sea levels rise due to global warming.

The good news is that tidal wetlands can help us both fight and adapt to climate change. They buffer floods by absorbing water, allowing the construction of lower levees, and they capture and hold carbon in massive amounts. In fact, scientists from the UN’s Intergovernmental Panel on Climate Change and the White House agree that wetland restoration is an important strategy for fighting global warming. A single acre of tidal wetland captures and converts around 2000 pounds of carbon dioxide into plant material each year, equivalent to the emissions from driving a car some 2280 miles.

Re-thinking Shoreline Development Recent scientific studies about rapid ice melt from Greenland to Antarctica create fear that the seas could rise even further. Scenarios like these are frankly “scaring the hell out of a lot of people,” as San Mateo County Supervisor Rich Gordon has observed. Rather than being paralyzed, we must act intelligently to protect and preserve our precious Bay shoreline. And we must make smart decisions about where to put new infrastructure, such as housing, as the Bay Area continues to grow. New development on the Bay shoreline, in particular, should be examined under the microscope.

Rising sea levels will of course threaten extensive high-value infrastructure all around the Bay, including ports and airports, housing and office parks. Decisions will have to be made about where to defend existing infrastructure, and in some cases where it may make sense to retreat to higher ground rather than commit to paying the long-term high cost of building and maintaining higher, hardened levees. The Peninsula faces perhaps more than its share of such decisions, with SFO, Foster City, Redwood Shores and other areas all in need of protection behind reinforced levees.

In the face of that reality, plans to put high value development in areas not already protected by levees should be viewed with a high degree of skepticism. As San Francisco Bay Conservation and Development Commission Executive Director Will Travis told the San Mateo County Board of Supervisors late last year “It may be better to abandon plans than to allow development and face the costs of protecting it from flooding….”

Of course, one such large development is being considered on the Peninsula — Cargill’s plans to develop its 1433-acre salt pond property in Redwood City. The proposal would be highly controversial even if it didn’t involve destruction of restorable tidal wetlands.

In fact, Cargill’s development proposal will likely propose to restore a portion of the property to wetlands. But wetlands too need to adapt to rising sea levels. Current projections suggest that South Bay tidal marshes will be able to keep up with sea level rise, capturing sediment to maintain their elevation. But as highlighted in a recent New York Times article, wetlands that are hemmed in by levees may well end up being destroyed.

Steps We Can Take That Will Make a Difference
Global warming is indeed a daunting international policy dilemma. But individuals should not feel paralyzed. The problem of sea level rise is a consequence of countless decisions aggravating a global problem — a problem that we can all mitigate through countless small actions. Local and regional policy land use decisions favoring smart growth over destruction of open space and wetlands are a very good place to start as well.

— Stephen Knight is Political Director with Save The Bay

Save The Bay works to counter global warming threats and educate the general public through volunteer programs, advocacy and public education campaigns

Published Spring 2008 in Green Footnotes.

Page last updated May 26, 2008.