I had to spend a couple hours this morning footnoting my next column for Discover so that it can be fact-checked. I had to assemble the papers I read, the web sites I visited, and the contact information for scientists who helped me understand the subject. One of Discover's intrepid fact-checkers will then spend many hours following in my footsteps and discovering where I tripped. He or she will have no compunction about writing up a detailed report of my mistakes. I'm sure some mistakes will turn up, and I won't be angry to see them in a fact-checking report. I'll be grateful that my column won't inadvertently misrepresent someone's research. And I'll be personally glad to have any misunderstanding of mine put straight. Fact-checking is an underappreciated art. As John McPhee explains in his recent essay, even a legendary fact-monger like himself benefits from the relentless skepticism of the New Yorker's fact-checkers. I got my own start as a fact-checker, and it was the best training I could imagine for science writing. Even when I don't have the luxury of fact-checkers vetting my own writing, I have an inner skeptic that drives me to double-check whatever I feel unsure about. One of the things I like most about blogging is the after-the-fact fact-checking that comes from commenters who catch mistakes. While accuracy is important for any kind of factual writing, it's particularly important in science writing, because there are just so many ways to get a story wrong. (Trust me, I know.) This old fact-checker gets rankled fairly often when I read about science on op-ed pages, because there doesn't seem to be much fact-checking going on there. It's not necessary for anyone to fact-check subjective statements like, "We must unleash the inventive genius of America," or "Harry Potter is boring." But imagine that someone writing a column about global warming (or the supposed lack thereof) wrote the following:

According to the University of Illinois' Arctic Climate Research Center, global sea ice levels now equal those of 1979.

Surely somebody should actually check with the people at the center to make sure that statement is true. If not the writer, then somebody whose job it is to make sure that paid columnists do not just make stuff up. Wouldn't the columns be better? Wouldn't the publication be better for such standards? Unfortunately, this is not just an imaginary scenario. George Will delivered this bit of information in his most recent column. And, as Talking Points Memo reports, the research center felt the need to post this statement on their own web site:

In an opinion piece by George Will published on February 15, 2009 in the Washington Post, George Will states "According to the University of Illinois' Arctic Climate Research Center, global sea ice levels now equal those of 1979." We do not know where George Will is getting his information, but our data shows that on February 15, 1979, global sea ice area was 16.79 million sq. km and on February 15, 2009, global sea ice area was 15.45 million sq. km. Therefore, global sea ice levels are 1.34 million sq. km less in February 2009 than in February 1979. This decrease in sea ice area is roughly equal to the area of Texas, California, and Oklahoma combined. It is disturbing that the Washington Post would publish such information without first checking the facts.

This is not a matter of the complex choices between cap-and-trade, carbon taxes, or other responses to global warming. This is a matter of exquisitely simple facts. 16.79 does not equal 15.45. Of course, this glaring error helps George Will make his case that global warming is nothing to worry about. But it is not true, and two seconds of fact-checking by the Post could have discovered that. It's fine for op-eds to be a place for opinions. But that doesn't mean they should be a vacation from facts. Update, 4/7: In fact, there is no such thing as the University of Illinois Arctic Climate Research Center. Details here.