How to deal with online polarisation?

Polarisation in society does not only happen offline. Online, too, people debate, groups dig in their heels and discussions sometimes turn hostile. It is therefore not unusual for cities and municipalities to face online polarisation in response to their own communication. As a local government or organisation, you may think it is better not to respond, but is that really the case? You can in fact influence how healthy and constructive your own online environment is. But how do you do that in practice?