Forty percent of our land is farmed or ranched, which is to say, the soil is basically conscripted as a food factory. The food system is already pervasively shaped by the Farm Bill, which spends nearly $15 billion per year on subsidies and $10 billion on conservation measures, deeply shaping what farmers grow and where, and tending to benefit large, industrially oriented operations. Food production can be much less carbon-intensive with changed practices in cropping, fertilizing, irrigation and waste management, many of them well suited to small farming. Moving in that direction, though, would require rattling the cage of big American agriculture.

As with energy, getting lawmaking involved wouldn’t be new. It has taken years of agricultural policy to get us into this mess. Getting out of it is a question not of whether lawmaking also produces economic policy and jobs, but of what kind.

The Green New Deal isn’t the only approach, of course, but its broad ambitions mark out the ground where future climate fights will happen. Because reshaping our environmental impact means reworking our economy, there will inevitably be competing visions about who deserves to benefit and what kind of economy we should build. Centrist proposals will concentrate on promoting investment in new technologies, with profits going, pharma-style, to private researchers and manufacturers.

If Trumpist nationalism outgrows its climate denialism but survives to fight again, it will double down on supporting national energy industries and denying the ethical responsibilities of global interdependence by building border walls against climate refugees. To the left of the Green New Deal, there will be louder calls to nationalize fossil fuels in order to leave them in the ground. (A carbon tax would be compatible with any of these visions, depending on who paid it and how the revenues were spent.)

Curiously, the idea that environmental policy could ever be separated from the larger economic order, or from fights over fairness, is recent, a product of an unusually technocratic period in American politics. Arguing for the Clean Air Act on Earth Day 1970, Senator Edmund Muskie, Democrat of Maine and the law’s lead drafter, insisted that “man’s environment” included “the shape of the communities in which he lives” and that “the only kind of society that has a chance” was “a society that will not tolerate slums for some and decent houses for others, rats for some and playgrounds for others, clean air for some and filth for others.”

For Senator Muskie, environmentalism meant that no neighborhood or job should be toxic. In the three years that followed, the country adopted the most ambitious and effective environmental legislation in its history, including Mr. Muskie’s Clean Air Act, the Clean Water Act and the Endangered Species Act. Mr. Muskie’s approach remains a model of visionary environmental lawmaking. Like much new radicalism, the Green New Deal is good sense rediscovered.

Jedediah Britton-Purdy (@JedediahSPurdy) is a professor of law at Columbia and is the author, most recently, of “After Nature: A Politics for the Anthropocene.”

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