California can’t meet its long-term climate goals without reducing its overall driving miles, per a state analysis of greenhouse gas emissions through 2050. This point was echoed in a recent New York Times article on SB 827, the measure to lift local restrictions on transit-adjacent housing. In the Times piece, bill author State Senator Scott Wiener said:

We can have all the electric vehicles and solar panels in the world, but we won’t meet our climate goals without making it easier for people to live near where they work, and live near transit and drive less.

Wiener isn’t just making that claim up. According to the California Air Resources Board’s staff report on regional greenhouse gas emission reduction targets, the state will need a reduction in vehicle miles traveled (VMT) through 2035 and 2050, even with more zero-emission vehicles sold and renewable energy deployed. They have a simple chart showing the calculations:

Basically, if by 2035 half of all new cars sales are zero emission, with half of all electricity (and thus transportation fuels) coming from renewable sources, we will still need a 7.5% reduction in baseline VMT.

The good news is all that clean technology means there would be slightly less pressure to reduce driving miles. But as the staff report pointed out:

The GHG emissions reduction contribution from VMT is a comparatively smaller in share than the GHG emissions reductions called for by advances in technology and fuels, but necessary for GHG emissions reductions in other sectors such as upstream energy production facilities and natural and working lands, and are also anticipated to lead to important co-benefits such as improved public health.

My one critique of the analysis is that it is conservative on the renewable mix by 2035. California has a statutory requirement to achieve 50% renewables by 2030, and we’re already over 35%. I would guess we’ll be at 60% renewables by 2030 and maybe 65% by 2035, not including greenhouse-gas free hydropower. In addition, bullish estimates of zero-emission vehicles could have the state at 75% battery electric vehicle sales by 2035.

Still, the point remains that VMT reductions are crucial. And worse, these VMT efforts could be badly undermined by autonomous vehicles, which could encourage more driving as people take advantage of having robot chauffeurs for every little errand and trip.

All of this analysis points to the need for much more housing production near transit and jobs — an outcome that SB 827 would directly promote. Because clean technology alone won’t be sufficient when it comes to reducing greenhouse gas emissions.