In “;The One Percent Doctrine,”; Ron Suskind writes that Vice President Dick Cheney announced in 2001 that if there was even “;a 1 percent chance”; that a threat was real, “;we have to treat it as a certainty in terms of our response. ... It's not about our analysis or finding a preponderance of evidence.”;

Cheney was speaking about national security and not about climate change. But many who refute climate change would agree that acting on little evidence is the right thing to do if the issue is serious enough.

Is the threat of catastrophic climate change serious enough? How would we know?

Science is a process that grows knowledge by consensus. Scientists read, listen, observe and experiment. They hash and rehash until the best tentative interpretation of the facts is reached by consensus.

The key word is “;tentative.”; Historically most of the scientific knowledge that we take for granted was hotly debated and gained acceptance by slow consensus.

The actual process of science has become opaque in a postmodern culture of sound bites and factoids.

We have become accustomed to science being a collection of facts and well-defined solutions, rather than a cauldron of uncertainty in which understanding ferments for decades or centuries before being refined into those neat diagrams in textbooks.

To aid policy decisions, compilations of data are used in watered-down grammar school presentations designed for policymakers. They avoid the painful (and boring) details but then are publicized only to be misunderstood and used by dissenters who believe they represent the whole picture.

What should we do with complex problems that have catastrophic potential when both sides present data that support their case, and neither side can be proved or disproved beyond a reasonable doubt?

There are several separate issues in the larger picture:

Is heat actually building up in the atmosphere and oceans? The data suggests yes, but not with absolute certainty.

If so, is the heat buildup significant, is it part of a natural cycle, how much can the system endure?

What effects would the buildup of heat have on arable land, human activities, habitats, etc.?

Is the change due to carbon dioxide, some other greenhouse gas such as methane, a combination of factors or something else entirely?

How much of the change is anthropomorphic, and is it reversible before it becomes catastrophic?

More important than whether the sky is falling is the question of which course of action has the worst possible outcomes.

Do nothing and risk catastrophic and irreversible change. Take the wrong actions and risk making things worse.

The policy decisions involve politics more than science, and I am glad I do not have to make them.