If our planet is going to survive the climate crisis, we need to act rapidly. We cannot wait for national governments to agree on how to reduce greenhouse gas emissions and keep the average temperature rise to within the 1.5 degrees scientists agree is needed to stave off cataclysmic consequences. David Miller argues that cities are taking action on climate change because they can--and because they must. His makes a clear-eyed and compelling case that if replicated at pace and scale, the actions leading global cities have taken to protect their citizens and become more resilient point the way to creating a more sustainable planet.