The Wall Street Journal’s “Numbers Guy,” Carl Bialik, has an intriguing story in today’s edition. Bialik’s piece includes a complex environmental problem and a communications challenge.

The environmental problem: There’s a big batch of plastic floating in a concentrated area of the Pacific Ocean (pieces of it pictured at right). It may be the size of Quebec – or it may be twice the size of the United States. It’s probably, on balance, not good for the ocean or marine life, but it actually does have some beneficial side effects.

The communications challenge: How do you portray the situation accurately, raising public awareness about the blob without overhyping it?

Bialik describes efforts to quantify the floating plastic and says that the most exaggerated measures of its size get used most often in press reports.

As it turns out, the person who discovered the plastic and has spent the most time with it is sort of guesstimating: “’I just did a very crude estimate, by getting a globe and placing my hand over the area defined by this current, and placing my hand over the continent of Africa’ to see how the two compared, he says.”

But that hasn’t stopped some environmental activists and journalists from presenting the largest size estimate as a fact – in an effort to stoke public interest.

This is a common practice among activists of all stripes. And it’s just as likely to be employed by politicians selling public policy or corporations pitching a product – pick the most extravagant claim (positive or negative) and make it stick.

Translation is also part of the problem. Scientists have to explain an issue to journalists, who typically have less expertise than the scientists. The journalists then have to translate the issue for readers or listeners, who typically have even less expertise than the journalists.

The scenario holds true for public policy responses to the financial crisis. Even many people who worked inside the financial industry don’t fully understand what happened. Members of Congress know less than the pros. And when Members have to explain it to constituents…. That’s when you get “Just blame X.”

On the road from reality to communications, complexity gets lost. The pros and cons become simply one or the other. The factoid or statistic that is most easily remembered gets the most play.

This can erode the effectiveness of the message. On the ocean plastic issue, Bialik quotes a Greenpeace scientist: “The problem with superlative statements that this is somehow a huge floating mass of plastic is that they inevitably lead to desensitizing people when they learn the truth of it.”

In the long run, the easiest hook may undermine a message if it can’t be backed up by strong evidence. Audiences tune out sources they don’t think they can trust – or messages that seem overwrought.

It’s very difficult to communicate a complex message to a lay audience. But maintaining message clarity and credibility requires zeroing in on details that are both punchy and solidly accurate, eschewing claims that may have some support but don’t hold up to closer scrutiny.

As professionals in the financial sector are learning, trust is valuable and, when lost, hard to rebuild.