In his speech announcing that the US would be withdrawing from the Paris climate agreement, President Trump framed the action as an act of solidarity with the Rust Belt voters who helped deliver him the presidency. "I was elected to represent the citizens of Pittsburgh, not Paris," he said.

To which Pittsburgh’s mayor promptly responded: Actually, we’re with Paris on this one.

Bill Peduto, the Democratic mayor of Pittsburgh, fired off a tweetstorm almost immediately, trolling Trump for his Pittsburgh line. It’s both entertaining and a serious reminder of the pivotal role cities will play in the fight against climate change in the wake of the Paris withdrawal:

There are a few quick points to make here:

1) The fact that Trump decided to invoke the name of a city that voted overwhelmingly for Clinton is a good distillation of how careless and politically opportunistic Trump’s withdrawal from the Paris agreement is. He surely could’ve chosen the name of another iconic Rust Belt town where he actually bested Clinton, but a speechwriter with a short attention span probably just liked the alliteration between the two cities.

2) Pittsburgh is a major metropolitan city, so it’s not surprising that its population would skew toward Clinton or support for the Paris agreement. But even if you’re charitable and extend your lens wider than Pittsburgh, the area is not filled with climate change deniers or Paris haters. A strong majority of the state believes in the existence of global warming, and about two-thirds of the state supports the Paris agreement. In fact, a majority of every state in the entire country does.

Yale Program on Climate Change Communication

3) Good climate policy might be dead on a federal level, but local policy matters — a lot. Cities produce about three-quarters of global energy-related CO2 emissions. In the US in the coming years, they’re going to be the primary battleground for the most important and ambitious energy policy in the US.

In a typically optimistic take on dire circumstances, Barack Obama said in his statement on Trump’s decision that “even in the absence of American leadership; even as this administration joins a handful of nations that reject the future; I’m confident that our states cities and businesses will step up and do even more to lead the way.” In other words, you go to war with the army you have.