Last week, Ceres, a coalition of investors that pushes companies to reduce emissions, and the National Resources Defense Council, released a little-noticed report that specifically compared the financial impacts, on power companies and consumers, of the Climate Security and Low Carbon Economy Acts. According to Ceres’ chief press officer, Peyton Fleming, the group based its calculations on a carbon emission price of $10 per ton, an admittedly low value, in part because of the safety valve clauses in the two bills. “We recognize that the cost of emissions is likely to be higher,” he said in an interview, “but we didn’t want to use that immediately and have [the bills’ sponsors] turn around and complain that safety valve will keep prices down.”

Keith Johnson at The Wall Street Journal’s Environmental Capital blog picked up the Ceres/NRDC report, making him one of the few journalists to base an article (or blog post as it were) on a comparison of the two climate bills. Still, because the report did not explicitly mention the safety valve or how it factored into the equations, the Journal entry didn’t either. “The gas tax is something that will affect people within the next four months,” Fleming said when asked about the dearth of coverage, “The safety valve is a complicated issue that won’t come into play until at least 2012.”

An article in E&E Publishing’s recently launched ClimateWire news service seems to be one of only two media accounts to dedicate their entire length to the subject (the other came from the Marketplace radio show last October). It is a long and fascinating account of the thirty-year history of the safety valve concept. It didn’t start with climate, but has evolved over the last decade to fit the mold. In 1997, the Clinton administration considered adding a safety-valve clause to the U.S. position at the U.N. climate negotiations that led to the Kyoto Protocol. It was dropped, however, after the idea met strong criticism from environmentalists. Bush thought about including a safety valve after his campaign pledge to regulate carbon dioxide, but he eventually abandoned regulation entirely.

McCain rejected a proposal to include a safety valve in the 2003 Climate Stewardship Act he sponsored with Lieberman. A year later, however, the National Commission on Energy Policy, a bipartisan coalition of industry, environmental, and political representatives, recommended that one be added to any cap-and-trade scheme in order to make it politically feasible (i.e. acceptable to industry and consumers). Apparently heeding that advice, Bingaman did exactly that when he pitched his draft legislation to Republican senators, including Specter, in 2005. Since then, debate has raged, pitting environmentalists, who think safety valves cripple climate legislation, against industry, which thinks having the failsafe is the only way to make cap-and-trade work.

It’s unclear what Obama and Clinton think. Yesterday, Grist’s David Roberts had an interesting Q&A with Jason Grumet, a climate and energy adviser to the Obama campaign who is also executive director of the National Commission on Energy Policy, which authored the 2004 report promoting the safety valve. Roberts notes as much in his introduction, but then, somehow, the safety valve doesn’t come up in the ensuing conversation. The interview is still well worth a read, but it’s too bad that contentious, but central element of the cap-and-trade legislation was once more overlooked, especially given the intense national interest in the gas-tax holiday.

Last month, Grumet sat on a panel in Washington, D.C., sponsored by the Society of Environmental Journalists, with representatives from the Clinton and McCain camps to “debate” the candidates’ green credentials. According to Darren Samuelsohn, who authored ClimateWire’s notable piece on the safety valve and attended the event, the subject of a mechanism to check runaway emissions prices did not come up. “It’s not been a factor in the presidential race,” Samuelsohn wrote in an e-mail. “Maybe when we get to the general, but it’s down in the weeds for the candidates for sure.”

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