Editorial

We are told that we must look to the "best science" when deciding questions of public policy. That's the only way, the reasoning goes, that the needs of the many, the greater good, can overcome political or economic considerations that favor the narrow interests of a few.

We find no fault in the logic that science should play a role when we consider solutions to the problems facing society. There's no substitute for hard facts. But what happens when the science is wrong, or its results are fashioned to favor a political agenda?

In 2006, the California Legislature passed the Global Warming Solutions Act. It was a sweeping measure designed to reduce carbon emissions to 1990 levels by 2020. Towards that goal, the state's Air Quality Board adopted tough new regulations in 2007 on off-road diesel emissions. To meet the standards, thousands of construction and other businesses will have to buy new equipment or perform costly retrofits on their existing equipment.

Last week the San Francisco Chronicle reported that in making its case to justify its harsh regulations, the Air Quality Board overestimated emissions from off-road diesel engines by 340 percent. The board has yet to explain the miscalculation.

Critics have suggested, however, that the board's "best science" was influenced by the political agenda of the environmental movement. Accurate estimates would prove inconvenient to those who desired sweeping regulations. Fudging the numbers by a factor of nearly three and a half provided a problem tailor-made for a radical solution.

Of course, mistakes happen. It appears no one knows that better than the staff of the Air Quality Board. The Chronicle also reported that board scientists last year said that 18,000 Californians die prematurely each year because of diesel emissions. The board later said that number was a bit high -- double, in fact, the number of deaths that could actually be attributed to the emissions.

Mary Nichols, chairwoman of the board, told the paper that these revelations don't cause her to question other calculations made by board scientists.

We should think not. Science, after all, evolves. Today's scientific fact is tomorrow's discredited theory.

Australian biologists at the University of Queensland studied 180 species that had been declared extinct by other scientists. Their findings, released last month, found that a third of the species were still alive and unaware that scientific study had rendered them unequivocally dead.

When making important decisions, elected officials, bureaucrats and the public should use the "best science" available. It's important, however, that we understand its limitations. At its best, science is only as good as the data used to reach a conclusion. It is a snapshot of what is now known, subject to change as new data is discovered.

When the data is conjured to reach a preconceived conclusion, it really isn't science. And of that we should all be wary.