For decades, devising a clear solution for California’s suburban sprawl and ensuing car culture has been the Holy Grail for smart-growth advocates. One trip on any of the Golden State’s perpetually clogged roadways during peak hours shows how ineffective most of those efforts have been. But with the state’s historic attempt to reduce greenhouse gas emissions in full swing, this might be changing.

As with Assembly Bill 32, the state’s primary greenhouse gas reduction plan, the impetus for this shift has come via state lawmakers in the form of Senate Bill 375, a measure that requires regional planners to make greenhouse gas reduction part of their overall growth strategy. In theory, the measure, authored by Senate Pro Tem Darrell Steinberg, a former Sacramento councilman, will do a lot more than that. According to the law’s proponents, SB 375 could finally push California developers out of the sprawl business and toward creating more sustainable communities where people live closer to public transit and their jobs.

Although SB 375 is complex, its primary goal is fairly simple: to reduce greenhouse gas emissions by getting people out of their cars. To do that, the law requires each of the state’s 18 metropolitan planning organizations to adopt a “sustainable communities strategy” that aligns land use, transportation and transit to encourage higher density development.

Each of the MPOs was asked to set its own projected reduction targets (one for 2020, another for 2035) for approval by the California Air Resources Board. In September, three of the state’s four largest regions, the Bay Area, San Diego and Sacramento, were approved for their targets of a 7 percent reduction by 2020, and between 13 and 16 percent by 2035. A decision on the fourth major region, Los Angeles, was put off until at least February to hash out fairly significant differences between desired targets: L.A. proposed 6 percent by 2020 and 8 percent by 2035, while the state wants 8 percent by 2020 and 13 percent by 2035. The rest of the MPOs fell somewhere in between, with two of the state’s smallest and least populated regions, Shasta County and Butte County, receiving targets of 0 to 1 percent for both years. Sacramento and San Diego are first up with their initial regional transportation plans to go before the air board in early 2011.

Overall, those plans are expected to reduce greenhouse gas emissions by about 3 million metric tons annually by 2020 and 15 million metric tons a year by 2035.

In exchange, developments that meet the standards will get relief from some of the requirements of the California Environmental Quality Act, or CEQA.

It is a common sense approach, supporters say, given that almost 40 percent of the state’s greenhouse gas emissions come from the vehicles we use to get around on a daily basis. And while AB 32 and other laws require cars to run cleaner than ever, no tailpipe emissions reduction would equal the effects produced by walking or biking instead of driving. The movement toward smaller, more energy efficient living also fits with what Sacramento Area Council of Governments Executive Director Mike McKeever says home buyers want these days.

“We view SB 375 as an implementing mechanism for achieving the blueprint goals we have already set for ourselves,” McKeever says. “If you go back to the 1980s and 1990s, we were building almost exclusively large lot, single-family suburban housing. The market is way more diverse than that now, and many people want a smaller product, smaller lots and a higher percentage of urban infill.”

A number of recent studies support that claim. The November 2009 Urban Land Institute report “Emerging Trends in Real Estate 2010,” which surveyed 900 industry experts from across the development spectrum, predicts smaller, denser projects will dominate in coming years, regardless of if and when the economy picks up.

“Next-generation projects will ori-ent to infill, urbanizing suburbs and transit-oriented develop-ment,” the report says. “Smaller housing units — close to mass transit, work and 24-hour amenities — gain favor over large houses on big lots at the suburban edge.”

And homes are getting smaller. New single-family homes, which had steadily grown bigger for decades, have shrunk almost 10 percent in size since 2007, according to the National Association of Home Builders. Curt Johansen, a longtime Bay Area developer and current president of TerraVerde Ventures Advisory, a Petaluma-based consulting firm that works with clients on sustainable development, says that trend has given home builders a new mantra: “Starter castles are out.”

Although such trends have historically come and gone, McKeever doubts the movement toward smaller is going away any time soon.

“The new housing stock that is being built today is significantly different than what was being built five years ago,” he says. “That was true when we were at the top of the market, and it’s true now that we’re at the bottom. We’ll have to see what happens when we get back to a revised version of normal. But I don’t see any reason that that’s not going to continue.

“Those kinds of projects, those that are 2,500- to 3,000-square-foot lots instead of 10,000-square-foot lots, are now all over this region,” McKeever says. “That’s suburban areas as well as urban areas. They’re already built, and more are in the planning stages. That’s now about 70 percent of what’s getting built. Five years ago those products were only about 20 percent of what was going up.”

With the market trending away from suburban sprawl, SB 375’s supporters say the law could also produce significant benefits for both taxpayers and local governments in the form of drastically reduced utility, fuel and infrastructure costs. A report issued in June by Gov. Arnold Schwarzenegger’s Strategic Growth Council claimed living closer to work will help Californians drive 3.7 trillion fewer miles annually by 2050, saving 140 billion gallons of gas. That would save residents about $6,400 on fuel and transportation costs each year and save the state approximately $194 billion in infrastructure costs.

In a report released in June, the Urban Land Institute notes that California’s expensive housing market has also virtually priced out many potential first-time buyers and renters. A decided increase in compact development “can provide the type of units that appeal to first-time renters and buyers and empty nesters, who are currently underserved.”

While SB 375 enjoys fairly strong support in the Sacramento region — many of the changes that ended up in the final bill were crafted in part by SACOG and the Sacramento-based California Building Industry Association — the law is not without skeptics. Some of the debate has parceled out along the same political lines as the brouhaha over AB 32, but much of the dissent comes from smart-growth advocates who contend that because SB 375 has no real enforcement measures, the law is essentially toothless. In that regard, its ultimate success depends on whether consumers, builders and community planners adhere to the intent and spirit of the law, not just its letter.

Living closer to work will help Californians drive 3.7 trillion fewer miles annually by 2050, saving 140 billion gallons of gas.

It wasn’t always so, however. In its original incarnation the measure would have withheld state and federal transportation funds from projects that didn’t adhere to the new law. But strong objection from both the building industry and local governments — who opposed what they viewed as state interjection into land use — convinced Steinberg to drop that element, making adherence to the statute largely voluntary. Instead, MPOs must develop a regional transportation plan that adheres with SB 375’s Sustainable Communities Strategy requirement, which the state air board must then approve or reject. If the board rejects the plan, the MPO can submit an alternate plan with suggestions for compliance. But even if that plan also fails, there is no penalty for noncompliance, save for the loss of CEQA relief for some projects. While in theory federal and state transportation funding could be redirected to other projects that are compliant, the final decision on how any of those funds are spent still rests with the local planning boards.

That reality frustrates local officials like Enita Elphick, mayor of Wheatland in Yuba County. “If you don’t have to comply with a law, what use is it?” she asks.

Other issues also remain. With money still historically tight, Elphick echoes the question asked by many local governments: “Who is going to pay for the changes to plans they have already adopted that are not in compliance with the MPO plan for their region?”

TerraVerde’s Johansen agrees that many local governments are going to need some kind of financial help if they are expected to come into the fold.

“The more help we can give cities with their climate action plans, the better the chance that SB 375 will be wildly successful,” he says.

The Urban Land Institute, which supports SB 375, suggests the state consider developing a consistent funding stream, such as the vehicle license fee, for just that purpose. But given the volatile political nature of that fee, which Gov. Schwarzenegger squashed when he took office in 2003, odds of that appear unlikely.

There are other interests at work as well. The California Chamber of Commerce is among many who wonder why the CEQA relief carrot applies only to residential housing projects and not to equally critical entities such as hospitals, schools and commercial job centers. In addition, the chamber has also called for giving all projects in an MPO with a state-approved plan safe harbor protection against environmental lawsuits. That same exemption would apply to projects funded by previously approved public funds, such as federal stimulus dollars or voter approved Proposition B bond money.

Johansen also says SB 375 must ultimately be streamlined, but his preference is to see that process tilted in favor of projects that are deemed sustainable. “We need to, once and for all, define what we consider to be sustainable and then to legally protect those projects,” he says.

But hitting the greenhouse gas reduction targets will entail more than giving developers a shield against lawsuits. It needs public support for a whole range of lifestyle changes, from more use of public transportation and carpooling to adapting to telecommuting. Businesses will also have to adapt, curbing all but the most necessary travel and relying more on Internet-based meeting software such as WebEx. Public agencies will also have to step up, finding new ways to reduce their own emissions output in their daily handling of everything from managing wastewater and solid waste to the cars and trucks they use in carrying out their duties.

Utilities are also now on the spot. At the same meeting in which the state air board adopted the MPO standards, it also endorsed regulations requiring both public and investor-owned utilities to secure at least 33 percent of their retail power from renewable resources by 2012. Because the new standard is under the auspices of AB 32, it is in question until voters weigh in on Proposition 23, which would halt the law’s implementation. The incoming governor could also delay it for a year or more.

Critics argue that hitting the SB 375 targets will lead to fuel price hikes that cost drivers unable to walk or take public transit thousands of dollars a year. Others question the logic of a mandated push for more public transportation at a time when budgets for most such agencies are being slashed to the bone.

For Lincoln mayor Tom Cosgrove, a former SACOG board chairman, arguments over the SB 375’s details inspire a sense of déja  vu.

“I’ve been around long enough that I remember when the earth was supposed to be cooling,” he says. “Now everything is supposed to be going the other direction.”

That dichotomy is not lost on him. Like many vested observers, he is both optimistic and guarded about SB 375.

“I just want us to approach all of this with caution,” he says. “I don’t want us to fool ourselves.”

A longtime member of the Placer County Transportation Planning Agency, Cosgrove says when it comes to getting people to truly change their behavior, success usually comes down to small details. Families, for instance, will always have a tougher time using public transit than will single adults. Condensed housing may also present challenges for families. In that regard, he has his own version of the popular mantra: “If you build it, they will come.”

“When it comes to these things, it really is a matter of, ‘If you build it in a way that is convenient and affordable, they will come,’” Cosgrove says.