GOOD POLICY should seem more convincing as it becomes more detailed. The Green New Deal championed by Alexandria Ocasio-Cortez, the newly minted Democratic superstar in Congress, has the opposite effect. For months the plan existed as little more than a slogan and a catch-all for progressive hopes and dreams. It would not just be a bracing proposal to confront climate change by reducing carbon-dioxide emissions to zero within ten years. It would also provide universal health care, a universal basic income, insulation from globalisation for workers, a jobs guarantee and other assorted goodies.

Critics of the proposal were derided by Ms Ocasio-Cortez’s millions of admirers and Twitter followers as anti-environmental and, possibly worse, anti-progressive. The counter-revolutionaries were told to wait for the details. On February 6th those details arrived in blueprint form, as a House resolution. It is a document with monumental ambitions and minimal detail. The most prominent Democratic contenders for their party’s presidential nomination—including Cory Booker, Kirsten Gillibrand, Kamala Harris and Elizabeth Warren—had all signed on even before the skeletal sketch was issued. They may come to regret it.

Unless governments can come up with policies to slow global warming, climate change will make life extremely unpleasant for mankind. To prevent a 1.5°C increase temperature relative to pre-industrial times, greenhouse-gas emissions would probably need to be halved by 2030 and brought to zero by 2050. There are sensible policies that America has not yet enacted that would bend its current trajectory on carbon emissions: a carbon tax, subsidies for nuclear-power generation, an increase in research funding for carbon-capture and carbon-storage, to name a few.

Yet the Green New Deal leapfrogs these ideas, which its creators deem too piddling and also too market-based to meet the proposal’s second objective: eliminating the excesses of late capitalism. At times the seemingly futuristic proposal sounds a bit Jeffersonian. The authors support “low-tech” carbon capture and storage for example—ie, planting trees—rather than developing more efficient technology. Pollution from agriculture would be eliminated by supporting family farming. Never mind that planting enough trees to make a globally significant dent in atmospheric carbon would require reforesting all 50 states, or that family farms are more resource-intensive than industrial operations.

Substituting high-carbon energy sources like coal for cleaner ones like natural gas, nuclear and bioenergy would do a great deal to push America towards decarbonisation. But insisting on decarbonisation within a decade—with renewable capacity still limited—would push up electricity costs rapidly. What would be the cumulative effects of mandatory, wholesale decarbonisation of the power-generation sector within ten years? Or of the mandated retrofitting of every single building in the country? Of the requirement for electric-only vehicles, and the removal of every single dirty internal combustion engine? Would it really provide “millions of good, high-wage jobs” and “provide unprecedented levels of prosperity and economic security” for the impoverished—as the resolution promises—or simply make them poorer?

In a single sub-paragraph, the American people are promised “high-quality health care; affordable, safe and adequate housing; economic security; and clean water, clean air, healthy and affordable food, and access to nature.” There is no further elaboration. Along with the previous guarantee of “a job with a family-sustaining wage, adequate family and medical leave, paid vacations, and retirement security,” this vision of American society is beautifully utopian. It quite literally promises the world. Yet each component of this paradise would require massive upheavals. Voters deserve a bit more explanation on how to get from here to there.

Such objections are thought unsportsmanlike by the proposal’s backers. The Green New Deal has people excited in ways think-tank white papers on cap-and-trade schemes never did. Boosters argue that it moves the “Overton window” of political dialogue: towards taking serious action on climate change. The little details, like how to pay for universal health care and a federal jobs guarantee can be dealt with later. Perhaps the Green New Deal will galvanise the youth vote, or help elect environmentally minded Democrats. Perhaps it is good politics to yoke environmentalism to other economic policies that could be popular.

Yet it seems rather more likely that the politics of the Green New Deal will backfire for Democrats. Republican strategists have stymied progress on climate change by caricaturing Democratic ideas as pie-in-the-sky efforts that would result in massive tax increases. Their parody now seems reality. The next Democratic nominee may well be someone who has endorsed the idea of the Green New Deal.

There is little wonder that Nancy Pelosi, who cares about climate change but also retains shrewd political instincts, has been so public in her doubting of the proposal. “The ‘green dream’ or whatever they call it, nobody knows what it is but they’re for it, right?” she told Politico. The bold plan could make the party unelectable in conservative-leaning states, ensuring that Republicans retain control over one chamber of Congress or even the White House and then stymie all climate legislation—whether sensible or not—for years to come.

There is a way to resuscitate the Green New Deal, and to harness the energy behind it. Its vagueness could be a virtue. Ms Ocasio-Cortez could retain the enthusiasm while rewriting the underlying policy so that it addresses a single issue—climate change. She and fellow progressives could make their enthusiastic pitches for universal health care, affordable housing, and boosting unions separately. Until then, the Green New Deal is unlikely to do anything to slow climate change. It may even get in the way of that goal.