Home Politics Economics California shows how states can lead on climate change.

California shows how states can lead on climate change.

California, which has long been a pioneer in fighting climate change, renewed its commitment to reducing greenhouse gas emissions last week by extending, to 2030, its cap-and-trade program, which effectively puts a price on emissions. It’s a bold, bipartisan commitment that invites similarly ambitious policies from other states, and it sends a strong signal to the world that millions of Americans regard with utmost seriousness a threat the Trump administration refuses to acknowledge, let alone reckon with.

The cap-and-trade program, which had been set to end in 2020, is the most important component of California’s plan to reduce planet-warming emissions by 40 percent (from 1990 levels) by 2030. The extension, along with a companion bill to reduce local air pollution, was passed by a two-thirds majority of the State Legislature, including eight crucial votes from Republicans. They defied a Republican president who has not only reneged on America’s global climate commitments, but has tried to undo every climate policy put into place by former President Barack Obama.

The hope among those who care about climate is that a combination of market forces, wider use of cleaner fuels and aggressive actions by businesses, states and cities can fill the gap left by Mr. Trump’s disappearance from the battlefield. There are many positive signs. Nearly 30 states require their utilities to seek at least some of their power from renewable sources; cities, prodded by former mayors like Michael Bloomberg, have increasingly been sharing ideas about emissions-cutting practices. More and more businesses are committing themselves to using renewable fuels.

And always, it seems, there is California, ready to take the lead until there are more responsible adults in the White House.

California’s cap-and-trade program requires power plants, natural gas utilities, fuel distributors and industries to buy permits to pollute, which decline in quantity over time. The idea is to put a price on emissions and, thus, discourage businesses and individuals from burning fossil fuels and encourage them to switch to cleaner sources of energy. The California program is linked with a cap-and-trade system in Quebec; Ontario will join next year. (A carbon tax is another way to put a price on greenhouse emissions; British Columbia, Finland and Ireland use this approach.)

Cap and trade is not a new idea; Congress and President George H. W. Bush used it successfully to reduce power plant emissions of sulfur dioxide, a major cause of acid rain. Congress considered a cap-and-trade program to address greenhouse gases; the House approved such a program in 2009, but the Senate did not.

California held its first auction of emission permits in 2012, and the state is well on its way to meeting its goal of reducing emissions to 1990 levels by 2020 with no obvious harm to its economy, which is booming. The state is using some of the money its cap-and-trade system generates to pay for a high-speed rail line connecting Los Angeles and San Francisco, which over time could help significantly reduce emissions from the transportation sector.

While there was broad support for the extension, some environmental groups like the Sierra Club California and a few Democrats opposed the legislative package for what they argued were unnecessary concessions to the oil and gas companies. The legislation is not perfect, but its benefits far outweigh its costs, and the country is better off for having it.

Attention now turns to the Northeast, where nine states, including New York, Connecticut and Massachusetts, are part of what is known as the Regional Greenhouse Gas Initiative, which, like California’s effort, is a market-based cap-and-trade program that goes beyond state boundaries. So far, R.G.G.I., as it known for short, has helped reduce emissions from power plants in the region by 40 percent between 2008 and 2016, according to the Acadia Center, a research and public interest group. States are now negotiating the future of the program beyond 2020.

The time has come to set a much more ambitious emission reduction target than the current rate of 2.5 percent per year. The time has also come for New Jersey to rejoin the group. Gov. Chris Christie took the state out of the agreement a few years ago, apparently because he thought that complying with it would be too expensive. But Mr. Christie is on his way out, and the Democratic and Republican candidates to succeed him want New Jersey to get back in. Virginia might also participate if the Democratic candidate for governor wins there in November — one more sign that Mr. Trump may be going one way, but America is going the other.