In many situations – especially those that can be characterized as a ‘tragedy of the commons’ or ‘free rider’ problem – taking the ethics of the situation seriously often involves ignoring the game theoretical aspects and applying a maxim of moral reasoning like the categorical imperative. If each actor behaves in such a way that their behaviour would be a good model for everyone to follow, then the problem of collective action goes away.
In terms of climate change, this sort of behaviour is important in areas like determining the appropriate policy for fossil fuel extraction. Every individual company and country has more to gain (at least in the short term) from digging up and selling fossil fuels then from restraining themselves. And yet every major fossil fuel producer will need to show restraint if we are to address the problem successfully. Not even Russia, Canada, and Saudi Arabia will benefit if we allow abrupt or runaway climate change to occur. The outcome is best for everyone when individuals ignore the reality that their actions alone will not determine the outcome of collective action, or when they are forced to behave as though they are ignoring that fact.
For those who don’t want the planet to be subjected to the risk of catastrophic climate change (say, warming of over 4˚C, which is where we’re heading now) the practical question is how to get individuals, companies, and states to behave as though they are taking the categorical imperative seriously.
Alternatively, perhaps we should abandon the idea that people will ever voluntarily restrain their pollution for the sake of others. In that case, we need a legal and institutional structure that makes behaving in an antisocial way personally costly (carbon taxes, restrictions on particularly harmful activities, etc).