Fear, culpability, humour ?

I choose some examples of sensibilisation campaign from Greenpeace and WWF. As we can see, they use choquing images to make people react. Actually I don't know which attitude is better to convice people to react (fear, culpability or humour). But I think it can be great to mix humour and informations in campaign. In this way, people won't feel bad and will enjoy the image and maybe this solution will help them to become volunteer in associations.

Examples of campaign: