The California Air Resources Board (CARB) approved a regulation that will have public transit agencies in the state transition to zero-emission bus fleets by 2040.
According to CARB, the transportation sector accounts for 40 percent of “climate changing gas emission” and 80 to 90 percent of “smog-forming pollutants.” The uncertainty in how much of the latter—the difference between 80 percent and 90 percent is non-trivial—is a bit concerning.

The organization reckons that as the transition starts to zero-emissions public buses starts and goes beyond the point of fulfillment there will be 19-million metric tons of greenhouse gas emissions not emitted into the atmosphere between 2020 and 2050, which is said to be “the equivalent of taking 4 million cars off the road.”

BYD bus for Fresno

According to the California Department of Motor Vehicles, there were 25,467,663 automobiles registered in the state as of December 2017, so there is still a whole lot of stuff going into the atmosphere.
A few other numbers need to be taken into account.
There are 200 public transit agencies in the state. Of the agencies, eight out of the top ten are operating zero-emission buses.
However, there are 153 of them, fewer than the number of transit agencies. And there are approximately 12,000 buses being operated in California.
CARB projects that based on orders or those that are “otherwise planned for purchase,” there will be 1,000 zero-emission buses in the state by 2020.
That means only 11,000 more over the next 20 years. Which certainly doesn’t seem insurmountable.
And reaching it will be a good thing for all who like to breathe.