California’s Global Warming Solutions Act of 2006 (AB 32, Nunez) requires the California Air Resources Board (ARB) “to adopt a statewide greenhouse gas emissions limit equivalent to the statewide greenhouse gas emissions levels in 1990 to be achieved by 2020.” In other words, the Act requires the state of California to ensure that its greenhouse gas (GHG) emissions in 2020 must be no higher than they were in 1990.
Subsequent legislation has emphasized the role that policymakers expect transportation and land use policies to play in reducing GHG emissions. SB 375 (Steinberg, 2008) said: “Without improved land use and transportation policy, California will not be able to achieve the goals of AB 32.” Accordingly, SB 375 assigned responsibility for achieving its emission-reduction objectives primarily to the respective metropolitan planning organizations (MPOs) for each major region in the state.
But how significantly do GHG emissions need to be cut to meet the targets set in the Global Warming Solutions Act? And what role might transportation and land use policies really play in reducing emissions?
How significantly do GHG emissions need to be reduced?
The Association of Bay Area Governments (ABAG) and the Metropolitan Transportation Commission (MTC) are currently well along in the preparation and adoption of the state-required regional transportation plan (RTP), titled Plan Bay Area. The plan is currently out for review in draft form, along with an accompanying Draft Environmental Impact Report (DEIR).
The Bay Area’s previous RTP—Change in Motion – Transportation 2035 Plan for the San Francisco Bay Area (2009)—claimed that emissions needed to be cut by 15% by 2020 to hit the 1990-level target. The 2013 update goes even further, suggesting that a 25 to 35% reduction in GHG emissions is now needed from current levels.
Plan Bay Area uses this as justification to shift surface transportation expenditures from roads to transit, impose restrictions and new costs designed to reduce driving, limit construction of single-family detached homes in the Bay Area and require that the majority of new residential construction be multifamily in designated areas around transit centers. Indeed, the Plan anticipates that in 2040 multifamily and attached/townhouse residences will be so popular that prices of existing single family detached homes will drop.
Yet data from the California ARB and the U.S. Environmental Protection Agency (EPA) paints a very different picture of California’s GHG emissions than ABAG and MTC’s Plan:
Based on the most recent ARB report, GHG emissions in 2010 were 447.87 million metric tonnes. This would only require a reduction of 4.7% to meet the 1990 target level—427 million metric tonnes of carbon dioxide equivalents (MMTCO2E).
That is a significantly smaller reduction than policymakers in the Bay Area are calling for. Yet for various reasons, even this 4.7% may still overstate the actual remaining GHG emission reduction requirement.
For starters, notice that the red line on the graph above (which covers 2000–2010) sits slightly higher than the blue line (which covers 1990–2004) for the period they both comprehend. The more recent report is 1.84%, 2.12%, 3.11%, 2.86% and 1.78% higher than the earlier for the five years, respectively, for a simple average of 2.34% higher.
The reason for this disparity is that ARB has adjusted its current GHG inventory method to conform to new Intergovernmental Panel on Climate Change (IPCC) protocols and other change factors. This means that a given amount of GHG emissions will be recorded as higher in the report covering 2000–2010 than in the report covering 1990–2004.
Crucially, however, ARB has not revised the 1990 GHG emissions figure upwards to reflect the new methodology. The effect of this is to increase the amount of GHG emission reduction required to meet the statutory target.
 Legislative Counsel’s Digest, page 1, paragraph 3, accessed May 12, 2013: http://www.leginfo.ca.gov/pub/05-06/bill/asm/ab_0001-0050/ab_32_bill_20060927_chaptered.pdf
The specific statutory requirement added may be found in HSC §38550: “By January 1, 2008, the state board shall, after one or more public workshops, with public notice, and an opportunity for all interested parties to comment, determine what the statewide greenhouse gas emissions level was in 1990, and approve in a public hearing, a statewide greenhouse gas emissions limit that is equivalent to that level, to be achieved by 2020. In order to ensure the most accurate determination feasible, the state board shall evaluate the best available scientific, technological and economic information on greenhouse gas emissions to determine the 1990 level of greenhouse gas emissions.”
 Accessed May 12, 2013: http://www.leginfo.ca.gov/pub/07-08/bill/sen/sb_0351-0400/sb_375_bill_20080930_chaptered.pdf
 ABAG/MTC, press release, ” Draft Plan Bay Area Released: Public Invited to Comment Online or at Public Hearings,” March 22, 2013, accessed March 24, 2013: http://www.onebayarea.org/regional-initiatives/plan-bay-area/draft-plan-bay-area.html
 ABAG/MTC, Plan Bay Area Draft Environmental Impact Report, April 2013, page 2.5-24, accessed April 25, 2013: http://onebayarea.org/pdf/Draft_Plan_Bay_Area/Draft_EIR.pdf
 MTC, Change in Motion – Transportation 2035 Plan for the San Francisco Bay Area, Final, April 2009, page 7, accessed May 13, 2013: http://www.mtc.ca.gov/planning/2035_plan/FINAL/T2035_Plan-Final.pdf
 DEIR, page 2.5-24.
 ABAG/MTC, Draft Plan Bay Area, March 2013, Table 1, “Draft Plan Investments by Function,” page 65, shows 62% of total transit plus road funding going for transit. (It should be noted that 5% of the total funding is “anticipated”—in other words, there is no current approved source for such funds— but these are “expected to become available within the plan horizon” (Plan, pp. 62-63).
DEIR, Table 2.1-13: Typical Weekday Daily Person Trips, By Mode, page 2.1-9, shows the percentage of all trips taken by transit increasing from 5% to 7% from 2010 to 2040. While this increase is questionable for a variety of reasons, this still leaves 80% of trips taken on roads—along with a substantial portion of the transit trips—and almost all local and many longer-distance freight movements.
 “The Plan Bay Area climate policy initiatives emphasize clean vehicles and smart driving. The proposed Plan includes a suite of programs including incentives to: promote a switch to clean and electric vehicles, extend electric vehicle ranges, increase car sharing and van pools and implement a smart driving strategy with in-vehicle fuel economy meters plus an education campaign. The initiatives also include funding to invest more in the most successful Climate Initiatives Grants funded under Transportation 2035. These grants are testing innovative and creative ways to reduce transportation emissions.” (DEIR, page 1.2-51).
Among other elements, this program includes a “Clean Fuels Feebate Program,” which would impose a fee on low fuel mileage vehicles to subsidize the purchase of higher fuel mileage vehicles (Plan, page 85); a proposed congestion pricing fee for San Francisco (Plan, page 82); and, for various Plan alternatives, a proposed “Transit Priority Focus” that would impose a development fee in high VMT areas (Plan, page 114), and a higher peak period toll on the Bay Bridge (DEIR, pp. ES-7 and 1.1-10), and a VMT pricing proposal (Plan, page 114).
 DEIS, page 2.3-5, “By 2040 it is expected that the share of housing demand will decrease for single-family homes …;” Table 2.3-2:Net Housing Supply and Demand by Building Type, 2010-2040, same page, shows demand for Detached/Single Family homes in 2040 to be 169,100—11%—lower than the supply of such homes in 2010.
 The Plan and DEIR focus on what they define as Priority Development Areas (PDA), and “PDAs are expected to accommodate 80 percent (or over 525,570 units) of new housing and 66 percent (or 744,230) of new jobs.” (Plan, page 55).
 DEIR, page 2.3-5, “The projected oversupply of single-family homes is expected to reduce demand for other housing types by almost 170,000 as some households that would otherwise choose multifamily units instead opt for single family homes made more affordable due to excess supply.” In other words, while the Plan projects that demand for multifamily homes and attached/townhouse homes will be far higher in 2040 than in 2010 (up 68% and 75%, respectively), the lack of demand for single-family detached homes (11% under 2010 supply of such residences—Table 2.3-2 for all data) will cause the price of single-family detached homes to drop compared to the price of multifamily and attached/townhouse homes, so that many households that would otherwise prefer multifamily or attached/townhouse homes will settle for the less desirable single-family detached homes. (We will leave it to the reader to make their own judgments about these projections of demand for, and prices of, homes in the Bay Area. However, it is worth noting that we know of no place in the U.S. where such changes have occurred. Moreover, we know of many areas where attempts to encourage non-single-family detached home usage by restricting additions to the single-family detached inventory has produced significantly higher prices for single-family detached residences.)
 ARB uses the term, “inventory,” in this context, to refer to the total GHG emissions for a year, which is different than the common financial accounting utilization of the term, which would refer to the measurement of the emissions in the air at a point in time, such as year-end. In accounting terms, the ARB concept would be similar to “cost of goods sold.”
ARB, “California Greenhouse Gas Inventory for 2000-2010 – by IPCC Category” (IPCC is the Intergovernmental Panel on Climate Change, an United Nations-sponsored organization) (summary report), accessed May 8, 2013: http://www.arb.ca.gov/cc/inventory/data/tables/ghg_inventory_ipcc_00-10_sum_2013-02-19.pdf
 ARB, Resolution 07-55, December 6, 2007, accessed June 9, 2013: http://www.arb.ca.gov/cc/inventory/1990level/arb_res07-55_1990_ghg_level.pdf
 ARB, “California Greenhouse Gas Inventory – by IPCC Category” (summary report), accessed May 8, 2013: http://www.arb.ca.gov/cc/inventory/archive/tables/ghg_inventory_ipcc_
 ARB, California’s 2000-2009 Greenhouse Gas Emissions Inventory Technical Support Document, page 1, accessed June 4, 2013: http://www.arb.ca.gov/cc/inventory/doc/methods_00-09/ghg_inventory_00-09_technical_support_document.pdf
 ARB has changed its methodology for an important reason, namely to comply with the accepted IPCC international standard methodology for GHG reporting. However, attempting to perform a detailed revision of the results for the years reported solely under the previous methodology, 1990-1999, was not done and is not likely to be done because “… the ‘gap’ in the overlapping years is primarily driven by revisions to activity data (e.g., gallons of fuel consumed, number of cattle used is [sic] estimating enteric fermentation emissions, etc.) and occasional revisions to methodologies (e.g., updates to emission models). Note also that the percent change for a given year between the overlapping years is only about 2 to 3%, not enough to suggest that the earlier data and methods vastly over- or underestimated emissions.” Source: Telephone conversation and e-mail exchanges with Webster Tasat, Manager, Emission Inventory Analysis Section, California Air Resources Board, May 22-24, 2013.
 EPA, Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2011 (EPA-430-R-13-001), April 12, 2013, “Figure 2-1: U.S. Greenhouse Gas Emissions by Gas,” page 2-1, accessed May 8, 2013: http://www.epa.gov/climatechange/Downloads/ghgemissions/US-GHG-Inventory-2013-Main-Text.pdf
 U.S. Bureau of the Census, California State & County QuickFacts, accessed June 16, 2013: http://quickfacts.census.gov/qfd/states/06000.html
 EPA, Table ES-2, “Recent Trends in U.S. Greenhouse Gas Emissions and Sinks,” pp. ES-5 to ES-7, shows CO2 as 83.7% of total gross GHG emissions for the 2011 reporting year.
ARB, Staff Report – California 1990 Greenhouse Gas Emission Level and 2020 Emissions Limit, November 16, 2007, Figure 1., “1990 Gross Emissions by Greenhouse Gas,” shows CO2 as 89% of total gross emissions, accessed May 8, 2013: http://www.arb.ca.gov/cc/inventory/pubs/reports/staff_report_1990_level.pdf
 U.S. Department of Energy, Energy Information Administration, Monthly Energy Review, May 2013, Table 12.1, “Carbon Dioxide Emissions from Energy Consumption by Source,” page 159: http://www.eia.gov/totalenergy/data/monthly/
 “Light-duty vehicle (truck) means any motor vehicle rated at 8,500 pounds GVWR or less which as a vehicle curb weight of 6,000 pounds or less and which has a basic vehicle frontal area of 45 square feet or less, which is:
(1) Designed primarily for purposes of transportation of property or is a derivation of such a vehicle, or
(2) Designed primarily for transportation of persons and has a capacity of more than 12 persons, or
(3) Available with special features enabling off-street or off-highway operation and use.
“Light-duty vehicle means a passenger car or passenger car derivative capable of seating 12 passengers or less.” 40 CFR 86.082-2, accessed June 19, 2013.
 Transit data is from American Public Transportation Association (APTA), 2013 Transit Fact Book: Appendix A: Historical Tables, Tabs 3 (Passenger Miles), 38 (Electric Power Consumption), and 39 (Fossil Fuel Consumption), accessed May 11, 2013: http://www.apta.com/resources/statistics/Pages/transitstats.aspx
All fossil fuel consumption is reported to the National Transit Database (the source of the APTA Fact Books) in diesel gallon equivalents by British Thermal Unit (Btu); electric kilowatt hours are converted to diesel gallon equivalents using a factor of 1 KWHr = 10.339 Btu (Stacy C. Davis and Susan W. Diegel (Oak Ridge National Laboratory) and Robert G. Boundry (Roltek, Inc.), Transportation Energy Data Book: Edition 31 (TEDB), July 2012, Oak Ridge National Laboratory for Vehicle Technology Program, Office of Energy Efficiency and Renewal Energy, U.S. Department of Energy, Table B.6, “Energy Unit Conversion,” page B-7.
Light Duty Vehicles (passenger car and light trucks, which includes vans, minivans, SUVs, and four-wheel pickup trucks) data starts with TEDB, Table 4.21, “Car Corporate Average Fuel Economy (CAFÉ) – Standards versus Sales-Weighted Fuel Economy Estimates, 1978–2011, Cars and Light Trucks Combined, pp. 4-22. It is assumed that the all data is for gasoline motor fuel, which is converted to diesel equivalents using data from TEDB, Table B.4, “Heat Content for Various Fuels,” page B-5, of 115,400 Btu/gal (net) for conventional gasoline and 128.700 Btu/gal (net) for diesel motor fuel, for a conversion factor of .8967 (this slightly understates actual light duty vehicle fuel economy, as there is a relatively small number of diesel-powered LDVs).
VMT was converted to passenger-miles traveled by the factors in National Household Travel Survey 2009, Table 16, “Average Vehicle Occupancy for Selected Trip Purposes.” (Values are given for 1995, 2001 and 2009, of 1.59, 1.63 and 1.67, respectively; for intermediate years, evenly separated intermediate values were utilized, 2009 value was used for 2010.)
 One potential way to reduce GHG emissions through expanded transit would be to emphasize service to marginally transit-dependent riders, particularly to reduce the utilization of older, less fuel-efficient, often poorly maintained and tuned vehicles. However, most of the major transit programs in California and nationwide are directed at high cost fixed guideway transit lines, which are very expensive—and generate very significant GHG emissions to build. (See Randal O’Toole, Does Rail Transit Save Energy or Reduce CO2 Emissions? accessed June 14, 2013: http://americandreamcoalition.org/pollution/RailEnergy&GHGs.pdf; and Todd Myers, Light Rail on I-90 Will Do Little to Reduce CO2, October 2007, accessed June 14, 2013: http://www.washingtonpolicy.org/sites/default/files/I-90%20Full.pdf). Indeed, most transit plans are aimed at building ridership among the more affluent, who generally drive newer, cleaner and more fuel-efficient vehicles, which further undermines transit’s effectiveness in reducing GHG emissions.
 Intergovernmental Panel on Climate Change, “Mitigation from a cross-sectoral perspective,”2007, http://www.ipcc.ch/pdf/assessment-report/ar4/wg3/ar4-wg3-chapter11.pdf p. 660 (20–50 US$/tCO2-eq is $20 to $50 per GHG ton).
 Benjamin Davis and Tony Dutzik, Frontier Group and Phineas Baxandall, U.S. PIRG Education Fund, for Public Interest Research Group, Transportation and the New Generation – Why Young People Are Driving Less and What It Means for Transportation Policy, April 2012, accessed June 14, 2013: http://www.uspirg.org/sites/pirg/files/reports/Transportation%20%26%20
 David Pace and Don Pickrell, National Transportation Systems Center, U.S. DOT, Driven to Extremes – Has Growth in Automotive Use Ended?, May 23, 2013.
Alan E. Pisarski, Have the Younger Population Lost Interest in Cars? – An Interim Report, Fall 2012.
 National Highway Traffic Safety Administration, “President Obama Announces Historic 54.5 MPG Fuel Efficiency Standard,” July 29, 2011, accessed July 2, 2-13: http://www.nhtsa.gov/About+NHTSA/Press+Releases/2011/President+
 National Highway Traffic Safety Administration, “Obama Administration Finalizes Historic 54.5 mpg Fuel Efficiency,” August 2012, accessed June 20, 2013: http://www.nhtsa.gov/About+NHTSA/Press+Releases/2012/Obama+
 This schedule does not identify where the remaining 1,082,000 MTCO2E of reductions from Alternative 1 to Alternative 2 come from. These are all from the “MTC Climate Policy Initiative”: “The Plan Bay Area climate policy initiatives emphasize clean vehicles and smart driving. The proposed Plan includes a suite of programs including incentives to: promote a switch to clean and electric vehicles, extend electric vehicle ranges, increase car sharing and van pools, and implement a smart driving strategy with in-vehicle fuel economy meters plus an education campaign. The initiatives also include funding to invest more in the most successful Climate Initiatives Grants funded under Transportation 2035. These grants are testing innovative and creative ways to reduce transportation emissions.” (DEIR, page 1.2-51) These “Climate Change Policy Initiative” changes have no direct connection with land use and can be implemented with or without land use changes. It is also questionable whether these proposals would prove successful in achieving the quantitative outcomes specified.
 ABAG Administrative Committee, March 9th, 2012, accessed May 29, 2013: http://mtcmedia.s3.amazonaws.com/audio/pc_2012-03-09.mp3
 DEIR, page 2.4-8.
 Driving and the Built Environment: The Effects of Compact Development on Motorized Travel, Energy Use and CO2 Emissions, a National Research Council report requested by the United States Congress, http://www.nap.edu/catalog/12747.html.