Last week, the Trump Administration moved to roll back the nation’s auto emission and fuel economy standards.  The current regulations are aimed at cutting tailpipe emissions of carbon dioxide, a major contributor to global warming.  The Trump Administration also demanded that California, which has its own state-based, more stringent auto emission standards, must follow the federal decision or face legal challenge.

California’s authority to regulate auto emissions has been supported by the courts and has allowed 13 other states, including New York, to follow California’s standards.  California, New York, Massachusetts and the other states following the stricter standards comprise more than a third of the national car market.

Introduced in 2012, the current federal rules require automakers to nearly double the average fuel economy of new cars and trucks to 54.5 miles per gallon by 2025.  If fully implemented, they would cut oil consumption by about 12 billion barrels over the lifetime of all the cars affected by the regulations and reduce carbon dioxide pollution by about six billion tons, according to the U.S. E.P.A.

So far, California hasn’t shown any interest in weakening their regulations.  In fact, California Governor Jerry Brown announced plans to have the state mandate that 5 million zero-emission vehicles be operated on its roads by 2030, up from a planned 1.5 million in 2025.  California has a legislative mandate to cut carbon dioxide emissions to 40 percent below 1990 levels by 2030.  California will also propose in the next few months that the state’s transit agencies buy zero-emission buses.

Whether the federal proposal will eventually trigger a legal battle with California is unclear and there have been media reports of negotiations between federal and state regulators.  But let’s hope that California does not buckle under the pressure.

Personal vehicles are a major cause of global warming.  Cars and trucks emit around 24 pounds of carbon dioxide and other global-warming gases for every gallon of gas.  About five pounds comes from the extraction, production, and delivery of the fuel, while the great bulk of heat-trapping emissions—more than 19 pounds per gallon—comes right out of a car’s tailpipe.  Cars, trucks and sport utility vehicles in the U.S. are responsible for about two-thirds of greenhouse gas emissions from the U.S. transportation sector.

For the first time in more than 40 years, the largest source of greenhouse gas pollution in the U.S. isn’t electricity production, but from the transportation sector.  Nationwide, nearly 30 percent of greenhouse gas emissions are generated in the transportation sector.  In New York, transportation is responsible for 41 percent of fuel-combustion greenhouse gas emissions in the State – almost double the emissions of electricity production.

Since cars are increasingly the dominant source of greenhouse gas emissions, countries around the world are racing to phase out gasoline and diesel cars.  China, the world’s largest car market, is working on a plan to ban the production and sale of vehicles powered only by fossil fuels.  In Germany, Chancellor Angela Merkel has hinted that it’s only a matter of time before the country that invented the modern car sets an expiration date of its own.

Norway has set the year 2025 as its goal to ban the sale of fossil fuel powered autos, India by 2030, France and the United Kingdom have set their goals for the year 2040.

As mentioned earlier, federal law allows states to either follow the federal requirements or adopt California’s tougher vehicle emission regulations.  Under the Obama administration, the federal standard was raised to match California rules.

Thus, the federal proposed rollback will increase greenhouse gas emissions – which heat the planet, and will allow higher levels of pollutants to be emitted by cars – which are a health hazard, particularly with regard to asthma.

California’s plans, it seems, are not only to dramatically increase the number of electric cars, but to also prohibit the sale of fossil fuel powered cars.  Last fall, the head of California’s Air Resources Board, suggested the state could move to set a date within the next decade to require the sale of only 100% new electric cars or those running on other renewable energy.  If California acts, New York should follow suit.

New York Attorney General Schneiderman has already promised legal action if the Trump Administration moves forward on its rollback plan.  Governor Cuomo, to his credit, has criticized the rollback plan.  But New York should do more.  New York must pledge to both defend California’s legal authority to protect the environment and, working with California, it should set a target date to move to the state toward banning the sale of fossil fuels cars.

In concert, these two states should act now to set a clear environmental policy goal that illustrates just how far the Trump Administration is putting the public’s – and planet’s – health at risk and to show what leadership looks like in the face of a rapidly heating planet.