In a surprise move ahead of this week’s Global Climate Action Summit in San Francisco, Governor Brown issued an executive order directing state agencies to achieve statewide carbon neutrality by 2045, with negative emissions thereafter.

Previous gubernatorial executive orders on long-term emissions goals focused on reducing emissions to 80 percent below 1990 levels by 2050. So the new 2045 target represents a significant acceleration, which will likely require massive deployment of “negative emission technologies” that sequester carbon at a scale most policy makers have not yet contemplated, as well as purchased offsets such as forest projects.

Significantly, the order does not require California to be zero-emission by 2045, which is basically impossible without yet-to-be-deployed carbon capture and storage technologies. So instead the state will continue its path-breaking greenhouse gas reduction efforts, and anything left over will have to be offset.

On one hand, executive orders do not carry the force of legislation and can be overturned by subsequent governors with the stroke of a pen. But on the other hand, executive orders on greenhouse gas emissions in California have tended to precede legislation that codifies them. So Governor Brown’s move today lays down a strong marker for the legislature to follow.

The order also represents a reaction to the growing urgency of climate change, as effects are felt worldwide in ways that are exceeding many scientific projections. And it also signifies optimism that the business community and international leaders (if not federal leaders here in the United States) can muster the investment and innovation necessary to deploy the needed technologies.