[On U.S. subnational climate action] The hardest thing that the cities are finding is transportation is really, really difficult to manage, because a lot of the tools are outside of their scope – the vehicles that are available. California cities are going to have an easier time because they're going to have a state that's leading on zero-emission vehicles.
[On U.S. subnational climate action] For all of the great things that are going on in these cities, it's only a small fraction of national emissions, and so it's really important that those cities that are pioneers, if you like, be much more focused on getting their pioneering to spread, and not just be thrilled with themselves about their pioneering status.
Ultimately, the differences between the two candidates are huge. I think if we have a second Trump Administration we're going to see even more of the [climate] action shift to the state and local level, and if we see a Biden Administration we're going to see action at the state and local level, but hopefully more federal support.
[On U.S. subnational climate action] When you add up all the efforts of the pioneers over the next decade or so, they’re going to be cutting US emission maybe four percent. So that’s a contribution. But we cannot stop the climate problem without much bigger cuts across the nation and ultimately across the whole globe.
Cities make great laboratories for combating climate change because some of the hardest tasks in cutting emissions involve activities such as urban planning and rebuilding transportation infrastructures — areas where cities are on the front lines. What's needed is for these leaders, like San Diego, to make their successes more visible — so that more cities here and abroad follow.
The really big effect of what Trump has done is to send a message to the rest of the world that the United States is not credible on climate change. The rest of the world is not going to know if we’re serious because we keep swinging back and forth. Over the past 50 years, the effectiveness in creating international deals came from U.S. leadership. And now nobody knows if we’re going to do that anymore.