A comment letter to the California Air Resources Board, by the Near Zero team and Stanford Law School professor Michael Wara, was quoted in a ClimateWire article on California’s proposed scoping plan update for 2030:

Academics warned that if the Trump administration interferes with the state’s waiver to enforce its tailpipe standards under the Clean Air Act, it could cost the state 52 million metric tons of CO2 emissions through 2030.

The state is also banking on about 111 million metric tons of reductions from the destruction of hydrofluorocarbons (HFCs) under its plan to address short-lived climate pollutants. About half of those reductions could be in jeopardy if the Trump administration abandons last year’s Kigali Amendment to the Montreal Protocol for ozone-depleting chemicals, the academics said, for a total of about 15 percent of the cumulative reductions the state needs to achieve by 2030.

“[T]he prospects for the Trump Administration following through on this international agreement are dim,” wrote Mason Inman, Michael Mastrandrea and Danny Cullenward of the Carnegie Institution for Science and Stanford University law professor Michael Wara. The administration recently defended a 2015 rule from U.S. EPA that eliminated some uses for HFCs in recognizance of the international agreement, however (Greenwire, Feb. 17).

Read the full article, “Industry groups stump for cap and trade” by Debra Kahn, on the ClimateWire website (subscription required).

In a follow-up after the article was published, Near Zero’s Danny Cullenward points out:

Debra is absolutely right to note that the Department of Justice recently defended EPA’s authority to regulate low-global warming potential HFCs under the SNAP program in response to an industry challenge (Mexichem Fluor, Inc. v. EPA).

Given DOJ’s recent reversals in other energy- and climate-related lawsuits, DOJ’s consistent arguments in favor of EPA in this case may reflect the administration’s support for (or indifference to) current SNAP policy. A few of the major companies that manufacture chemicals in this area support the SNAP regulations, so perhaps the administration has received mixed messages from the business community. Or perhaps this is just a low-profile case that didn’t rise to the level of political attention so soon after President Trump’s inauguration.

In any event, we didn’t cover this legal risk in our comment letter. Going forward, however, we’ll keep a close eye on what the D.C. Circuit decides, since a loss for EPA in this case could undercut California’s broader effort to control HFC emissions.

Meanwhile, the 51 MMtCO2e in planned HFC reductions we identified as at risk are a separate matter. With low odds that the U.S. Senate will ratify the Kigali Amendment to the Montreal Protocol, these reductions are in question even if the D.C. Circuit finds in favor of EPA in Mexichem Fluor.