When it comes to reducing greenhouse gas emissions in California, one size does not even come close to fitting all.

That's all I could conclude after the SB 375 Regional Targets Advisory Committee (RTAC) and metropolitan planning organization (MPO) representatives touched on an amazing array of policy and technical issues during an all-day meeting on Tuesday.

All right, I could also conclude that what has been a highly technical process may be on the verge of becoming very political.

The session provided a way for the state's 18 MPOs and the committee to give final input to Air Resources Board staff before it issues greenhouse gas (GHG) emissions reductions targets to the MPOs in late June. Under SB 375, the MPOs must use the GHG targets to formulate regional sustainable communities strategies that guide transportation and land use decisions. Because passenger vehicles account for more than one-third of GHG emissions in California, the idea behind SB 375 is to employ land use planning and transportation policies that reduce the amount that people drive.

Repeatedly, the MPO representatives and even the RTAC members said that policies which reduce GHG emissions in one region may have little effect in another region. Concepts that are obvious in major metropolitan areas are foreign in more lightly populated regions. Political agendas in San Diego, San Francisco, Stockton and Thousand Oaks are not the same. A moderate transit expansion in Sacramento may produce significant results, while a far more expensive transit expansion in L.A. would have virtually no impact on vehicle miles traveled. "Smart growth" policies that are mainstream in San Luis Obispo County are unknown in Shasta County.

"I've heard some things today that have illustrated some fundamental differences in what regions are going to be able to achieve," said Pete Parkinson, who represents the American Planning Association's California chapter on the RTAC.

Much of the meeting's focus was on defining "achievable." What became clear is that technical achievability and political achievability are not the same.

Just about everyone in the room on Tuesday was on board with transit-oriented development, compact mixed-use communities, highway tolls, building mixed-income housing next to employment sites, reducing the amount of free parking, and vastly expanding transit service. The environmental, economic and social benefits are obvious, right?

Well, no, they're not, at least not to the people who make decisions and to the voters who elect those people. Repeatedly, RTAC members and MPO representatives insisted that whatever comes out of the SB 375 process must contain a large dose of political reality.

"There are clearly local political issues," warned RTAC member Carol Whiteside, a former mayor of Modesto. "I think we underestimate the political difficulties local jurisdictions are going to have with implementing some of the land use recommendations."

Southern California Association of Governments Executive Director Hasan Ikhrata said that MPOs must "attach reality to what we are doing." Preparing a politically unrealistic "fantasy plan" will only cause people to turn away from the larger effort, he said.

Two representatives from the house-building industry provided a measure of that political reality on Tuesday. They argued that the assumptions in MPOs' models for future development – which leaned heavily toward multi-family housing – were faulty.

"Many of the housing type of assumptions and the density type of assumptions …may not pan out in the real world," California Building Industry Association lobbyist Richard Lyon said.

Andy Henderson, Building Industry Association of Southern California general counsel, sounded what may become a familiar theme as SB 375 implementation goes forward: Make someone else do it. Raise parking prices, tax gasoline or provide incentives for people to buy cleaner-burning cars, he suggested.

"You could interfere with the recovery we need to see in building houses," Henderson said. "We can't be putting in place impediments to that recovery."

Those are the type of arguments we'll probably be hearing often in September, when the campaigns for and against repealing AB 32 – the 2006 state law that mandates GHG emissions reductions – grow heated. September is also precisely the time when the Air Resources Board is scheduled to finalize regional GHG emissions reductions targets.

Political reality, indeed.

– Paul Shigley