PARIS — A pastry maker from northern France, Vincent Picard describes himself as a “militant ecologist” — one who also joined the so-called Yellow Vest protests a movement set off by a planned increase in France’s gasoline tax.
Mr. Picard, 32, acknowledges that a gas tax might encourage conservation. But he has to drive to work every day. The nearest train station is 35 minutes away. The trains run only once an hour, and soon perhaps even more infrequently as the government looks to save costs on rural routes.
“I am conscious that we have reached the end of fossil fuels and that we have to modify our habits,” he said. “They are asking us to to be mobile, to adapt, but this cannot be done from one day to the next. You have to continue to live.”
The gas tax is part of a continuing effort by France, starting in 2014, to raise the taxes on fuel in order to encourage conservation and the use of alternative energy sources to fight global climate change.
But the Yellow Vest protests have become the biggest obstacle yet to putting it in place and point to the difficulties not just for France, but for nearly all industrialized countries committed to pulling the world back from the cliff’s edge of catastrophic climate change.
France’s cancellation of a fuel tax increase this week in the wake of increasingly violent protests signaled the perils and political headwinds governments in wealthier countries may face when that transition is ill-conceived.
There is little doubt among scientists and economists that putting a price on carbon — and a high one at that — is essential in the effort to reduce fossil fuel dependence. The question is how to design a carbon tax — and how to cushion the blow for the most vulnerable.
Many analysts point out that President Emmanuel Macron’s government succeeded in crafting a tax that wasn’t all that environmentally smart or politically deft.
The French have been far more tolerant than most societies in accepting high taxes on gasoline and diesel fuels already. The cost of a gallon of gas in France is about $6 or more — taxes accounting for about 60 percent of that — compared with about $3 on average in the United States, where high fuel taxes have been a nonstarter.
The government’s tax, which was written into the law before Mr. Macron was elected, was the tipping point for hard-pressed families already laboring under some of Europe’s highest tax burdens, and not just for fuel.
Rather than spurring the effort to cut fossil fuel use, the misstep now threatens to set it back.
It angered those who can least afford to pay more to get to work and drop off their children at school. Fossil fuel champions — including President Trump — jumped on it. And it landed with a thud during the critical United Nations climate change negotiations underway in Poland, which Édouard Philippe, France’s prime minister, was forced to skip because of bubbling unrest at home.
More than that, the decision this week to put a moratorium on the tax increase came after protests nationwide turned violent, causing four deaths and millions of dollars in damage and injuring more than 250 people.
If nothing else, the maelstrom in France showed that the political challenge of how to create incentives for people to conserve energy and convert to cleaner sources requires much more than raising a tax on gas at the pump or subsidizing solar panels.
The violent blowback by the Yellow Vest movement — named for the roadside vest adopted by the protesters that signals drivers in despair — exposed many failures.
Of the 34 billion euros, or $39 million, that Mr. Macron hoped to raise from the fuel tax, less than a fourth was earmarked for environmental measures, said Daniel M. Kammen, a professor at the University of California, Berkeley who specializes in energy policy.
Much more of the fuel tax proceeds, Mr. Kammen said, could have been used to lower the prices of electric vehicles, including taxis, to help make it more affordable for people to commute from areas with no public transportation links. Or it could have been used to develop more charging stations or subsidize big batteries to enable taxis to do long trips.
“So while President Macron has highlighted the need for funds to invest in clean energy, that is not actually what was planned,” Mr. Kammen said.
Politically, the backlash came from those who could least afford to give up their cars — small-town and suburban residents priced out of big cities and unhappy with Mr. Macron on a host of other issues already. It did not help that Mr. Macron had lowered taxes on the rich in one of his earliest tax code changes.
Like most policy measures, a tax on fossil fuels can be painful if badly constructed.
“This situation illustrates how equity and fairness considerations have to be built into the design of such policies,” Alden Meyer, policy director at the Union of Concerned Scientists, said by email from Katowice, Poland, where United Nations climate talks are underway.
Others agreed. “There is a consensus among economists who have said that to fight against the warming climate, there must be a price put on carbon, but they underestimated the social repercussions that could have,” said Jean-Marie Chevalier, a French economist and professor emeritus at the University Paris-Dauphine.
“The people in the street do not give a damn about the energy transition,” said Mr. Chevalier, who worked for many years with Cambridge Energy Research Associates, whose clients include business and governments worldwide.
In Canada, conservatives have pledged to undo Prime Minister Justin Trudeau’s plans for a national carbon tax. Only six of 10 provinces are going along with his plan.
In Australia, when Malcolm Turnbull tried to advance a law that would have reined in greenhouse gas emissions this year, he was ousted as prime minister.
Similarly, in the United States, where the car is king, public transportation lags and the automobile and energy industries maintain powerful lobbies, politicians toy with low fuel prices at their own risk.
What France’s experience has made clear is that fuel taxes work best as part of a more comprehensive and holistic plan that also tries to offset the disproportionate pain felt by lower-income workers who can least afford the changes.
Mr. Picard, the pastry chef, for instance, earns €1,280 a month, or about $1,450, after payroll taxes. For him, the planned tax increase of 6 or 7 cents per liter of gas “is enormous,” he said.
“Imagine how violent this tax is for those people who earn less than me and who are not conscious of environmental needs,” added Mr. Picard, who lives in Woincourt, a village of 500 people about 45 miles from Amiens, Mr. Macron’s hometown.
But if those struggles are unfamiliar to Mr. Macron, a millionaire and former investment banker, many who study climate change goals sympathize with the Yellow Vests and support making relief part of the package.
“Everybody loves to talk about climate goals and preserving the environment, but nobody is talking about the now,” said Vonda Brunsting, a researcher at Harvard’s Kennedy School who works on environmentally responsible investment policy.
“Some governments are intent on having ambitious plans for meeting the Paris climate conference goals, but they have to survive politically long enough to put them in place,” she added. “Macron and the French government have skipped over the part involving the workers and the community.”
Among the forms of help that economists point to are offering subsidies to encourage people to use less-polluting forms of energy, and expanding transit networks rather than closing them. Flexibility is a virtue, too, like reducing the fuel tax level if oil prices raise the cost too high.
Another element, especially in France, is increasing workers’ disposable income by pushing for higher wages and indexing fixed incomes for the elderly so that they can better afford energy-efficient technology.
“We are in the transition period and the government has run into political economic problems,” said Philippe Aghion, an economist at the prestigious College de France who advised Mr. Macron during his presidential campaign. “So you need to smooth out this period. You need to reach out a hand to help people across the bridge.”
He believes a number of countries may have to to violate the European Union’s 3 percent cap on annual deficits so that they can borrow more to fund their energy transitions.
The cap “was not designed for countries undergoing structural reforms,” he said, adding that the bloc should be willing to do so since it will eventually lead to more long-term wealth.
Camilla Born, who analyzes energy policy at the research and advocacy group E3G, said that while Mr. Macron could be faulted for not putting in social measures that would allow French citizens to “ride out the challenges of change,” the price of inaction was ultimately far more costly.
“The reason we need to take action,” she said, “is because the social and economic costs of climate impacts are far worse.”