SB 375’s Emissions Gap: Explained


Editor’s Note: Many of the points made below were also conveyed recently in comments to the Air Resources Board on the development of the update of the Mobile Source Strategy.  Read our letter


Most of the scrutiny over emissions reductions in the “SB 375 category” (our phase for reductions related to reduced emissions from the use of cars and light trucks) have focused on regional transportation plans and the implementation of Sustainable Communities Strategies (SCSs). But little attention has been given to the additional state strategies called for in the Scoping Plan. This omission is puzzling because the amount of emission reductions from additional state strategies actually exceeds the emission reductions from the current round of SB 375 targets.

Let us explain:

What is the 7 Percent Gap in CARB’s GHG Emission Reduction Framework?

There is a seven percent gap in the California Air Resources Board’s (CARB’s) Scoping Plan framework to achieve reductions in SB 375 category emissions. The gap results from the difference between the 25 percent reduction need identified in the Scoping Plan and the 2018 SB 375 targets that equate to an 18 percent statewide reduction.  As a result, there is 7 percent gap between the SB 375 targets and the Scoping Plan objective.

CARB acknowledges that although the SB 375 targets “make significant progress,” they do not “provide all of the reductions that will be needed” to meet the State’s climate goals.  [See Scoping Plan, page 75; see also Scoping Plan-Identified VMT and State Climate Goals, page 4].  CARB’s Staff Report to Update SB 375 Targets (2018)  identifies the 7 percent gap in GHG emissions as “new State-initiated VMT reduction strategies.”

What are the SB 375 Targets?

The SB 375 targets require Metropolitan Planning Organizations (MPOs) to incorporate a set of GHG reduction strategies (called a Sustainable Communities Strategy or “SCS”) within a Regional Transportation Plan.  The current targets range from 13 to 19 percent per capita and result in an 18 percent reduction in SB 375 Category emissions statewide.  [See Scoping Plan-Identified VMT and State Climate Goals, page 3].

How Do the SB 375 Targets Fit Within the Scoping Plan?

The Scoping Plan describes how to achieve the GHG reduction goals set by SB 32. The statutory goal requires a 40 percent reduction in statewide emissions by 2030 (from the total emissions in 2020). It also lays the groundwork for how the state can achieve an 80 percent reduction by 2050. [See Executive Orders S-03-05 (Schwarzenegger) and B-30-15 (Brown)].

The Scoping Plan calls for “SB 375 emissions” (again, our phrase) to decrease by 25 percent. [See Scoping Plan, page 75.] This figure derives from an assumption that vehicle miles traveled (VMT) should decrease by 15 percent by 2050 (based on the Executive Order goal) in yet another CARB document called the Mobile Source Strategy. [See 2016 Mobile Source Strategy, page 36-37; and model details on page 166].

If you were reading closely, you may have caught that the SB 375 targets and Mobile Source Strategy goal do not align. The SB 375 targets achieve per capita GHG emission reductions by the year 2035 using 2005 as a base year and the Scoping Plan/Mobile Source Strategy assume VMT would decrease in years 2030 and 2050 (by 7.5 and 15 percent respectively), but uses 1990 as a base year.  Then there is the issue that GHG reductions per capita does not correlate perfectly to VMT reduction.  Making matters more complicated, only the “40 percent by 2030” goal is in statute; the “80 percent by 2050”  is in an executive order.

CARB estimates that the SB 375 targets will yield 8 MMT of CO2 reductions in 2035. The estimate for radditional state strategies is 10 MMTs of CO2 reductions

Confusing, we know.

After a lot of math, ARB reconciled the differing authorities, metrics, and target years. It estimated that progress toward a 15 percent VMT reduction in 2050 would be a 7.5 percent reduction by 2035.  CARB then determined that a 7.5 % VMT reduction was the rough equivalent of a statewide SB 375 target average of 25 percent. [See Scoping Plan, page 75; see also: ARB SB 375 Workshop Presentation, slide 19].  That is how the 25 percent goal in the Scoping Plan is derived.

But remember, the actual SB 375 targets only average an 18 percent reduction statewide.

How to the State Emissions Compare to the SB 375 Targets?

CARB calculates that the SB 375 targets will yield 8 million metric tons of CO2 per year in 2035. But the GHG emissions reductions needed from state strategies are 10 million metric tons CO2 per year.  See Staff Report to Update SB 375 Targets (2018) (page 35).

Why Weren’t the SB 375 Targets Set at 25 Percent?

The short answer is that MPOs do not have sufficient authority. CARB explored setting higher targets but concluded that MPOs lacked sufficient resources and authority.  [See Scoping Plan-Identified VMT and State Climate Goals, page 3]. For example, “other factors,” that are outside of MPO control, like gas prices and employment, affect travel behavior. The constant change in external factors requires policymakers to “think through what tools and practices will allow each region to meet its goal.” [See SB 150 Report, page 24].

Is There a Plan to Address the Seven Percent Gap?

No. The Scoping Plan recommends that the gap be addressed by additional VMT measures “mentioned in Appendix C. .” [See Scoping Plan, page 79]. Appendix C lists about 30 high-level policy concepts that the state should “explore.” Many of these policies (like pricing and land use controls) require a heavy political lift. The nine-page document lacks a fiscal analysis or discussion of priorities.  As a result, it is difficult to conclude that the policies in Appendix C are part of a larger integrated plan.

Another place to look is Table 17 of the Scoping Plan (See Scoping Plan, page 103), which provides a list that includes potential statewide strategies. But again, there is no comprehensive plan to achieve reductions beyond the 18 percent assigned to MPOs. One of the state’s most recent actions is to add the SB 743 VMT analysis into the CEQA Guidelines. This new rule will likely affect land use economics in a way that will yield GHG reductions. [See our SB 743 Resource Center]. But it would be aggressive to think it would cover all, or even most, of the seven percent gap.

Table 17 of the Scoping Plan also lists three additional strategies:

  • Pricing.  Policies to support low-GHG transportation (e.g., road user, parking pricing, transit discounts)
  • Performance Measures.  The state will harmonize performance with emission reductions and increase the competitiveness of transit and active transportation modes vial guideline documents, funding programs, and project selection.
  • Electric Cars (ZEVs).  The operation of 1.5 million zero and hybrid electric vehicles on California roads by 2025; and 4.2 million by 2030.  (Note: this goal would reduce GHG emissions, but not necessarily lead to VMT reductions).
[See Scoping Plan, page 103]. Of these, ZEV policy and pricing measures fall clearly outside the authority of MPOs. Harmonizing performance with emission reductions in state grant programs also falls within state authority, although many MPOs apply similar selection criteria to increase the competitiveness of different project types.

What Can Be Done?

The nature of many of the external factors driving how much people elect to drive their cars suggests that we should be forming better partnerships across state, regional, and local levels of government.  On this point, we concur with the language of the SB 150 Report:

“Structural changes and additional work by all levels of government are still needed to implement regional strategies. Staff and elected officials of local, regional, and state government have critical authorities and roles to contribute. … But as a whole, all actors responding rationally to the incentives, political forces, and policy restrictions in front of them have not been able to enact the magnitude of change needed. … The current structure of policies and lack of incentives will continue to produce and exacerbate the insufficient results unless shared responsibility, changes in authority or mandates and incentives, and strong, deliberate, collaborative action is taken to change them. CARB finds that this disconnect impedes progress on attaining the SB 375 targets and their co-benefits.”

[See SB 150 Report, page 56].

In other words, achieving the full reductions in the “SB 375 category” requires cooperation at all levels of government: local, regional, and state:

  • While no single agency or level of government alone bears the responsibility for this work; there is an important opportunity to partner across many agencies on taking collaborative action toward better results. [See SB 150 Report, page 4].
  • More discussion among a broad suite of stakeholders from transportation, the building community, financial institutions, housing advocates, environmental organizations, and community groups are needed to develop the needed set of strategies to achieve necessary VMT reductions. [See Scoping Plan, page 75].
  • California – at the state, regional, and local levels – has not yet gone far enough in making the systemic and structural changes to how we build and invest in communities that are needed to meet state climate goals. To meet the potential of SB 375 will require state, regional, and local agency staff and elected officials to make more significant changes across multiple systems that address the interconnected relationship of land use, housing, economic and workforce development, transportation investments, and travel choices. [See SB 150 Report, page 6].

What’s Our Point?

Better understanding. People give us confused looks every time we say that there is a 7 percent gap in the state strategy to reduce emissions that is impeding the state’s ability to achieve its goal.  We are sympathetic: it’s difficult to sort through all the CARB documents to draw a distinction between the reductions in the SB 375 targets and the Scoping Plan. There is also a lot of room for misinterpretation. That is why we relied so heavily on ARB’s documents here. Our hope is that in distilling all this information it will help build common ground among stakeholders. Hopefully, it helped.

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