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Reducing Greenhouse Gas Emissions from Vehicle Miles Traveled

The California Global Warming Solutions Act of 2006 (AB 32) commits California to reduce its greenhouse gas (GHG) emissions to 1990 levels by 2020. The transportation sector is the top GHG emitter in California, contributing roughly 40 percent of all California emissions. Poor fuel efficiency and high vehicle miles traveled (VMT) are primary contributors to transportation sector GHG emissions. Meeting California’s GHG emissions reduction goals requires reductions in both per-mile emissions and vehicle miles traveled. Fuel efficiency has been addressed historically by federal Corporate Average Fuel Economy (CAFE) standards, and California has passed its own legislation regulating GHG emissions from vehicles.

Vehicle miles traveled, however, have historically not received legislative attention, and have been growing at a much faster rate than population or the economy. There is consequently a “VMT gap” in the current regulatory structure for GHG emissions reductions envisioned under AB 32. This Article addresses how AB 32’s developing market-based GHG emissions reduction policy, allowing for carbon offsets, could interact with implementation of the California Environmental Quality Act (CEQA) to support emissions reductions from transportation-related land use projects. Allowing carbon offsets for CEQA land use projects requires the California Air Resources Board (CARB) to acknowledge that the degree of GHG mitigation required for transportationrelated land use projects is discretionary under the CEQA process; otherwise, CARB would face the legal conundrum of allowing industry to claim offset credits for mitigation considered compulsory under a separate legal statute.

Carbon offsets for CEQA mitigation should be recognized as being additional to emissions reductions that would otherwise take place without offset investment dollars. This is because significant land use changes are necessary to meet California’s long-term GHG reduction goals and it should be a legal priority to facilitate these changes. This outcome would be most consistent with the existing CEQA regime and would increase incentives and funding available to implement GHG emissions reductions from land use-related projects.

Further, we recommend that a regional transportation authority (also known as a Metropolitan Planning Organization or MPO)—the same agency charged with modeling the impacts of future development plans on GHG emissions under recent legislation designed to address vehicle miles traveled (under SB 375)— facilitate quality offset projects and coordinate offset investment dollars for CEQA mitigation. We argue that such a carbon offset program under AB 32 will prove to be more significant than SB 375 in addressing vehicle miles traveled by promoting increased investments in transportation-related land use projects.