Just how scarce was climate-change coverage in 2011? It’s hard to get a fix on the details, but the broad conclusion that it was even scarcer than in the year before seems to hold up.

Last week, I wrote a post about an analysis by The Daily Climate—a website that produces and tracks news about climate change—which found that the number of articles, blog posts, editorials, and op-eds “declined roughly 20 percent from 2010’s levels and nearly 42 percent from 2009’s peak,” based on a review of its own archives of aggregated climate stories.

The conclusion about the downward trend “felt right” to journalists that sent me e-mails responding to the piece. But they were miffed at my decision to report The Daily Climate’s rankings of specific outlets’ year-to-year productivity. I did point out—by way of update that should’ve been included from the outset—that The Daily Climate’s analysis was based on a review of its archives, which are “meant to provide broad sampling of the day’s coverage, not a comprehensive list,” according to its editor, Douglas Fischer. Therefore, the rankings did not reflect the various outlets’ actual productivity.

I could have stressed the uncertainty in the rankings more strongly than I did, however (an explanation of The Daily Climate’s aggregation strategy, which relies on automated and manual searches, can be found here; the strategy is methodical, but obviously subject to random variations in what the website’s researchers are following, what they catch, and what they miss).

In fact, it’s very difficult to tease out the finer details about outlets’ absolute and relative productivity. Take Environment & Energy Publishing (E&E), which produces Greenwire, ClimateWire, and four other news services. In The Daily Climate’s archives, E&E ranked fifth among all climate news producers in 2011, but the archives contained 29 percent fewer stories from E&E than they did in 2010. A few people at E&E complained, arguing that a lot of their material is kept behind a pay wall and that the figure did not represent the company’s actual output, so I e-mailed Editor-in-Chief Kevin Braun in search of more precise information.

Even the in-house tally would be “a tad rough,” Braun emphasized, but he quickly pulled together some stats. The drop in climate coverage between 2010 and 2011 was more on the order of 13 percent than 29 percent, by his lights. The change would have been larger if Braun had searched for “climate” rather than “climate change,” he said, but the former strategy produced a lot of false positives. “A quick scan indicated I was catching too many congressional stories where someone mentioned ‘climate policy,’ or something similar but climate change was not necessarily the focus of the story,” Braun wrote in an e-mail.

There was “no question” that climate coverage has declined over the past three years, Braun said. By his measurements at E&E, it is down 38 percent from 2009. But he thinks that is “almost entirely due” to the lack of attention to climate change on Capitol Hill. A breakdown of productivity at E&E’s various publications supports that explanation. There’s been relatively little change in the amount of climate content on ClimateWire, a minor decline at Greenwire, and a significant decline at E&E Daily, which focuses on Congressional coverage. Furthermore, Braun said, a 13 percent year-to-year decline may sound big, but in practice, it means that E&E was producing roughly nine stories per business day in 2011 versus ten in 2010.

It’s harder to say how E&E performed relative to other outlets last year. Aside form E&E, The Daily Climate ranked the top five producers of climate stories, from highest to lowest, as Reuters, The New York Times, The Guardian, The Associated Press. My own Factiva search showed a smaller decline at the Times than The Daily Climate had reported and much larger declines at the others than estimated by The Daily Climate. Factiva also showed a decline at The Sydney Morning Herald, which The Daily Climate had noted as a rare case of increased coverage.

My data from Factiva and Braun would also re-order the top five producers—with Reuters still on top, followed by E&E, The Guardian, The Associated Press, and The New York Times.

So, while it would be useful to have the kind of detailed data that would allow critics to tease out nuanced trends in climate coverage (for instance, it seems like the decline at The New York Times has occurred almost exclusively in its news pages, and not at all on its blogs, according to Factiva), any attempt to gather such details is going to be subject to a fair amount of uncertainty.

What’s seems indisputable is that, when it comes to the amount climate coverage overall, all signs point down. “I should note that I completely agree that, in general, there’s been a major decrease in climate policy coverage in the MSM,” Braun wrote in one of his e-mails. “In 2007, I certainly would not have guessed this!”

Indeed, few would have, and the fact that the decrease is evident even at E&E, where it can’t be chalked up to editors and reporters who don’t know or don’t care much about the story, is worrisome. There’s still a lot of really good climate change journalism out there, of course—and quantity does not equal quality—but it’s spread more thinly, and journalists are having tougher time finding solid pegs on which to hang it.

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Curtis Brainard is the editor of The Observatory, CJR's online critique of science and environment reporting. Follow him on Twitter @cbrainard.