Well, it seems to me to be a rule of thumb in biology: if something has significant costs then it has significant function. Usually function is fairly obvious in our bodies but not with consciousness.
Some options are:
- It has no function whatsoever. It can safely be ignored and is not necessary for our thoughts and action to be understood. Just relax, enjoy the show but dont take it seriously.
- It is a product of the process of forming memories. Memory has a function but consciousness by itself does not.
- It is a method of different parts/modules/processes in the brain to communicate with each other. This assumes that our brains are so compartmentalized that without consciousness there would be not unity in our actions.
- It is a model of the world created from our senses, memories, knowledge and in-born a priori concepts. We live and act within this model and have no naive direct knowledge of the world.
- It is a model of the world created as above but projected into the near future. We live and act within this model but it is not time lagged and can be used to monitor actions by comparing the error between previous projection and current perception.
I am tentatively working on the assumption that consciousness is a model of the world that is the raw material for our memory and also a way to live in the present through projection for the near past into the near future and furthermore a global view that all parts of the brain can access if they require a global view.