If you want to know why so much legislation, both in California and in Washington, has an “eat your vegetables” feel to it, you only have to look at the Public Policy Institute of California poll released this week.

The poll found that 85 percent of California adults are convinced that global warming has either begun to happen or will happen in the future. Seventy-seven percent feel it’s at least a somewhat serious threat to the future quality of life in California and 75 percent believe that steps need to be taken immediately to counter the effects of global warming.

But later on in the poll, two-thirds of employed Californians say they usually drive to work alone.

That’s even though 62 percent of adults in the state believe air pollution is a problem where they live.

Anyone catch the disconnect here?

Polls like this cause cynics to throw up their hands and complain that people can’t be trusted to know what’s best for themselves, with the unspoken suggestion that those important decisions should be left to the politicians.

That attitude misses the point. People typically know – and do – what’s best for themselves. The trouble lies in convincing them that what’s good for the neighborhood/city/state/country/world is also in their own best interests.

It ain’t easy.

Let’s take the Bay Area, which long has been the most bicycle-friendly region of the state. In San Francisco, the city has spent millions to add bicycle lanes to almost every thoroughfare, along with passing laws requiring bike racks on the streets and in new developments and even making traffic improvements that disgruntled motorists complain favor bikes over cars.

Statewide, the PPIC poll shows that 3 percent of Californians now bike to work. In the Bay Area, the percentage jumps to 5 percent, but that’s still far below the 70 percent who commute by car.

Even though the Bay Area leads the state with16 percent of adults taking public transit to work, a number that will plummet if BART goes out on strike next week, it’s clear that even in California’s greenest bastion, people love their cars.

Driving is simple, convenient, familiar and not that expensive. For many people, there’s just no reason to change to a commute method that’s not only different, but also likely to be a bit of a personal hassle.

But in a state where people constantly profess to worry about air pollution, global warming and future environmental problems, there ought to be some way to get people out of their cars.

There already are plenty of negative incentives. But soaring gas prices, increasingly crowded roads and ever-lengthier commutes haven’t been enough to convince people to give up their vehicles.

Cities like San Francisco, for example, already are looking at more drastic measures. Some new condominium and apartment developments provide little or no off-street parking, private cars are being banned from some city streets and there’s serious talk about congestion pricing, which would charge motorists who venture into the city’s downtown during weekday business hours.

So far, though, nothing has worked. According to the PPIC, solo driving reached a low of 62 percent in 2008, but has been 65 percent or higher since 2011, despite gas prices that have climbed above $4 a gallon. There’s been plenty of grumbling from drivers, but little change in their habits.

But if the stick doesn’t work, what about the carrot? That’s the idea behind Plan Bay Area, a blueprint for regional development approved earlier this month by Northern California transportation and government groups.

The plan would channel future population growth into relatively dense developments within walking distance of mass transit, such as BART stations and railroad terminals.

Putting more than three-quarters of the 2 million new residents expected in the area by 2040 near transit would make it easier for them to either give up their cars or at least use them a lot less.

There are plenty of complaints about the plan, especially from suburban residents upset about what they say is the future “urbanization” of their quiet enclaves. But politicians from cities like Oakland, San Francisco and San Jose are just as adamant that the suburbs need to take a fair share of the projected new residents.

But is a state that’s reeling under the growing burden of traffic and pollution, the beauty of Plan Bay Area is that it offers a chance to ease the crush of cars.

By making mass transit a more convenient and efficient commuting option, the hope is that people can choose what’s best for them and still do what’s right for everyone else.

John Wildermuth is a longtime writer on California politics.