The ability to use metaphor is the sign of a good author — and at the beginning of an essay it can make for a powerful opening. If we wish to communicate with people who do not have a scientific background it helps if we know how to communicate in a way that is readily understandable and meaningful. It helps if we can engage in storytelling, telling people not simply the science but why we got interested in the science, not just the physics behind climate change but how it will affect real individuals. and it helps if we know how to communicate complex concepts in a simpler language.

Storytelling is integral to the human mind. When we give a scientific explanation to ourselves or to others we are still engaged in a form of storytelling, using the very same parts of the brain that Homer and storytellers in the long-forgotten past spoke to thousands and even tens of thousands of years ago. We are trying to lead someone from where they are along a path to where we would like them to be — so that they see things the same way that we have been able to see them.

Rather than focusing too heavily on the science, we need to get back to the roots of scientific explanation in storytelling whenever possible, illustrating what the effects of climate change will be on farmers, villagers and our descendants. Telling the story of how climate science became important to you, or the story of some historical figure such as Arrhenius and how he arrived at his insights.

And yes, it helps to make use of metaphor — because like storytelling metaphor is integral to the human mind.

As I said previously in a somewhat different context:

We are talking about the importance of metaphors to human psychology, and at root they are important psychologically because they are of critical importance to human cognition. We speak of a "tree" of knowledge, but we also speak of "branches" of knowledge or "branches" of a discipline, "viewpoints" or "perspective", the justification or evidence that "supports" a given conclusion, the "foundation" for a belief, "lines" of "investigation" and so on. Metaphors — where we think of something concrete as a means of "grasping" something more abstract.

The more abstract concepts probably begin as metaphors. The word "abstract" has its origins in a concept meaning "to draw away from" or "separate". The word 'metaphor' has its origins in the Greek noun "metaphora" which has its origin in the the verb "metapherein" with "meta-" meaning "over" or "across" and pherein meaning to "carry" or "bear".

We begin with concrete, perceptual awareness and we are able to abstract to higher levels only gradually. And to do so we will often have to rely upon metaphor first - as a means of tacit awareness that only later makes possible an fully articulated form of understanding.
Through metaphor we are able to get back to primordial roots of human thought - and in my view this is what explains their psychological power. Storytelling and metaphor are important - quite possibly as important if not more so than the actual science when it comes to public understanding.

Addendum

Since writing the above, the following has been brought to my attention, and may be of some interest:

Extensive studies and analyses have been done on a broad range of our most basic concepts, such as time, cause, event, mind, thought, memory, self, knowledge, morality, etc. These studies reveal that virtually all of our abstract conceptualization and reasoning is structured by metaphor (Gibbs, 1994; Kovecses, 1990; Lakoff, 1987; Lakoff & Johnson, 1980, 1999; Sweetser, 1990; Turner, 1991; Winter, 1989, 1999).

These metaphors are conceptual in nature, and not merely linguistic (Lakoff, 1993). Technically, a conceptual metaphor consists of a conceptual mapping of entities, properties, relations, and structures from a domain of one kind (the source domain) onto a domain of a different kind (the target domain)....

Fernandez-Duque, Diego; Johnson, Mark L. (January 01, 1999) Attention Metaphors: How Metaphors Guide the Cognitive Psychology of Attention, Cognitive Science, Vol 23 (1), pp. 83-116 (Open Access)