Motorists in the famously lefty city of Berkeley, Calif., could one day be confronted with a “CO2 ALERT” when they fill up their tanks.

Berkeley’s Community Environmental Advisory Commission has approved a proposal to mandate climate warning labels on gas pumps. It would require the approval of the city council before it could take affect; a council vote is expected in the coming months.

The idea is to mimic warning labels on cigarettes. It’s being pushed by Beyond The Pump, a group of San Francisco Bay Area activists associated with 350 Bay Area. If approved by the council, Berkeley would become the first American city to impose such a requirement. (Similar, but more specific, labeling proposals have been floating around Europe for years.) The tentative label design is shown on the right.

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“I’d like to see this become a statewide policy for transportation emissions,” campaign manager Jamie Brooks told Grist. “We’d like to see it as a systematic point-of-sale ordinance, like the cigarette packs. We want to connect cause and effect for consumers.”

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Perhaps unsurprisingly, the oil industry is freaking out at the idea that its customers could be confronted with reminders about the climatic effects of their gas-guzzling practices. In a letter sent to Berkeley’s planning department last week, Western States Petroleum Association President Catherine Reheis-Boyd argued that such a rule would be unconstitutional, setting the stage for a possible lawsuit. “Far less restrictive means exist to disseminate this information to the general public without imposing onerous restrictions on businesses and forcing unwanted speech in violation of the First Amendment,” wrote Reheis-Boyd.

Berkeley climate change warning label

Raymond PajekAlternative label suggestion

She then compared the petroleum industry’s nascent struggle against climate warning labels with the historic free-speech movement at U.C. Berkeley in the 1960s. “Perhaps no city in our nation has as rich a tradition in the exercise of the First Amendment right to freedom of speech as the City of Berkeley,” Reheis-Boyd wrote. “Throughout times of tremendous civil upheaval in this country, citizens of this City have exercised great courage in resisting efforts by those at all levels of state and federal government to force them to agree with or advance government opinions.”

OK, thanks for the disingenuous lecture. Now, about all that global warming?