Initial estimates for an ambitious Bay Area GHG target

The “Big Four” among California’s metropolitan planning organizations — SCAG (Los Angeles/Southern California), MTC/ABAG (San Francisco Bay Area), SANDAG (San Diego), and SACOG (Sacramento) — govern regions that feature urban population densities and relatively mature transit networks.  Abundant opportunities exist in the urban cores of all four regions to ratchet up the intensity of land use in locations that are well-served by both existing and planned transit.  These MPOs also share skills and expertise that will be valuable while implementing Senate Bill 375, including blueprint planning, congestion management, pricing mechanisms, and funding incentives.  Despite possessing these relative advantages over other MPOs in California, there are still challenges, as well as myriad unique local distinctions that could conceivably be taken into account by the Air Resources Board (ARB) when it issues draft regional targets in June.

One particular characteristic of the Bay Area is its expensive real estate market.  This creates an imbalance of housing and jobs at the regional scale, thereby generating interregional commutes from Central Valley cities like Tracy and Manteca, where upwards of 70% of residents commute to Bay Area jobs.  Higher relative household incomes in the Bay Area also diminish sensitivity to user fees and other changes in price — though we shouldn’t forget that in the Bay Area, as elsewhere, higher gas prices in 2008 noticeably increased transit ridership.

In order to get a sense of what an ambitious GHG target would be for the Bay Area, MTC has relied primarily on aggressive pricing and land use assumptions.  In light of the region’s comparably higher household income level, MTC modeled a pricing assumption much more ambitious than those employed by its peers in the “Big Four”: a 460% increase in the cost of automobile use.  This translates to an automobile usage cost of over $1.15 (2009 dollars) per mile driven in 2035.  That cost increase incorporates new revenue sources, particularly congestion pricing, increased parking charges, and a carbon tax.  It can be difficult to gather political support for these types of measures, particularly in the current economic downturn — but it also seems clear that we will need to turn to these revenue sources in the future.  Their inclusion in this model is therefore appropriate.

MTC also modeled land use assumptions that are much more aggressive than current projections.  These assumptions decrease the population at the fringe of the Bay Area (particularly in Solano and Contra Costa counties), and they correspondingly increase the population of the urban core — including a 22% increase in San Francisco’s population above existing, already optimistic projections.

These assumptions translate into the following per capita GHG reductions (compared to 2005):

• Implementing the Bay Area’s most recent Regional Transportation Plan yields GHG reductions of 5% by 2020 and 3% by 2035.
• Adding either land use or pricing assumptions to the RTP yields GHG reductions of 7% by 2020 and 10% by 2035.
  
• Adding both land use and pricing assumptions to the RTP yields GHG reductions of 10% by 2020 and 12% by 2035.

Other scenarios were considered as well, but the bottom line is that the 12% figure represents the current ambitious target for Bay Area GHG reduction by the year 2035.  It is questionable whether this target is achievable in light of its aggressive underlying assumptions.  Nonetheless, inputting less aggressive assumptions into more robust models could potentially yield more reduction than anticipated.  This preliminary analysis suggests that there is room for the Bay Area to achieve a more ambitious target that goes beyond business as usual.  An ambitious GHG target presents an excellent opportunity for the Bay Area to develop a Sustainable Communities Strategy that demonstrates the benefits of coupling infrastructure investments with creative land use and pricing strategies.