What would you have to say?
First I would mainly address the people of the rich countries as they are responsible for climate change. I would ask them to really think about the things they could do and why they do not do them. Because everybody knows that travelling much by car is bad for the climate, but they continue to take the car to go shopping, whereas some very few people take the bicycle. But if you ask them why they take the car everybody has his answer ready. I would explain why 95% of these answers are pretexts. It is possible to do it, so do it. It does not matter if you are the only one, then you can be even more proud to be a good example for the others. Who else has the power to change something in this world if not the people who live in it. In all the western countries with democracies the citizen is part of every political decision taken, because he elected the politicians. The rich countries are the ones able to react, if they do not, there is no excuse and they will have to admit that they did not want to react.
Climate change is a serious subject because it concerns the whole world and our future. We all should be aware of the consequences we have caused and we will cause if we immediately don’t stop to reduce the emission of CO2.