The world wide fund for nature sponsors an ad showing a person morphing into a fish with the caption, "stop climate change before it changes you." this is an example of which type of appeal?

This is an example of "fear appeal".

Fear appeals recommend to the purchaser that he or she can maintain a strategic distance from some negative understanding and effect through the buy and utilization of an item or service, an alteration in conduct, or a diminishment in the utilization of an item or benefit, or the reception of a thought - for this situation, the idea of the reality of environmental change.