John Edwards spun through New Orleans like a, well, not like a hurricane. On Saturday he blew in and out of the city where he launched his campaign a year ago without causing much of a stir.


Edwards pegged his visit to the storm-hobbled city to (surprise) a climate-change agenda, calling it “the great moral test of out time.” A nice sentiment, but a bit of a clich√© at this stage of the campaign. Most of the press, meanwhile, was still focused on an opposite corner of the country, and a man who isn’t even running for president.


New York City Mayor Michael Bloomberg had made a much braver proposal the day before, while rubbing elbows with over 100 of his colleagues at a climate-change summit sponsored by the U.S. Conference of Mayors in Seattle, Washington. In a keynote speech on Friday, Bloomberg suggested a national tax on carbon dioxide or other greenhouses gases in order to curb climate-warming emissions.


Taxing carbon is not terribly popular, even among environmentally sympathetic politicians and most of the current presidential candidates (with the exception of Chris Dodd). A cap-and-trade system, which would price emissions using a credits market, is far more popular. Edwards is among those who favor this approach, and next to Bloomberg his moralizing in New Orleans landed as flat as old soda.


Most of the news articles that covered Edwards’ visit, including one from the Associated Press, led with his climatic call to arms, but quickly shifted to long discussions of his criticism of Hillary Clinton. His opinion of her is identical to his opinion of the current government’s attention to global warming: both are plagued by the status quo. But, as the press has it, his critique didn’t get much more specific than that. For talk of real change on the climate front, or at least something really different, most reporters kept to the non-candidate.


“In calling for a carbon tax, Mr. Bloomberg was again speaking out on national issues, as he has on gun control and public health matters like smoking and obesity,” wrote Sewell Chan, on The New York Times City Room blog. The Republican-turned-Independent’s electoral ambitions have been the source of great speculation this campaign season, although the Times reported in October that those ambitions had “fizzled.”


Bloomberg has made bold environmental legislation one of his signature acts. Last spring, he garnered headlines when he unveiled a sweeping, green development plan for New York City, which included a controversial, eight-dollar “congestion pricing” initiative for cars driving into lower Manhattan. But cutting vehicle exhaust at the city level is just the beginning.


When it comes to national, industrial polluters such as the oil, gas, and chemical companies, “Most economists consider a carbon tax a more effective instrument for reducing greenhouse gas emissions than” a cap-and-trade, Chan wrote on the Times blog (which has a full transcript of Bloomberg’s speech). Even the big businesses most likely to be affected by carbon pricing have begun to see the sense in a tax, which many predict would be a more familiar and clear-cut system. As a billionaire entrepreneur who made his fortune off a machine that tracks financial markets, Bloomberg’s endorsement will likely buttress other calls for taxation.


The fact that the mayor’s announcement, and the climate summit in general, received so much media attention is testament to the new significance of energy and environment issues this campaign season. All of the Democratic candidates, as well as John McCain on the Republican side, support some form of anti-warming legislation. It was expected, then, that Bloomberg’s speech in Seattle would prompt reporters to inquire anew about his presidential aspirations. “He didn’t address that directly Friday but said there are already plenty of candidates in the race, and they all need to be pressed to give detailed environmental plans,” The Seattle Times’ David Postman reported from the scene.


Bloomberg wasn’t even entirely specific about what type of tariff he supports, although he did mention that a $15 excise on every ton of greenhouse gases would allow the government to return $500 a year to taxpayers in payroll tax rebates. As of last week, the mayors of 728 cities had signed onto an agreement to cut eighty percent of their municipalities’ greenhouse gas emissions by 2050. In a worthwhile article that adds useful context to the Seattle meeting, the Los Angeles Times reported Sunday that a lot of the cities have already achieved reductions, although many challenges remain if they are to meet the targets recommended by the scientific community.


At any rate, there has been far more action on climate issues among cities than at the national level, so it is little wonder that a would-be presidential candidate managed to steal the spotlight from an actual one this weekend.

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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.