The aggressive timeline shows that much of Europe remains committed to ambitious climate regulations even as other major economies, including the United States, have yet to take binding action. If European nations agree to the 2040 target, it would put the E.U. on track to meet a much bigger goal, in 2050, of “net zero” carbon neutrality.

The E.U. has long touted this transition as an opportunity, not a sacrifice, but it is unclear if it can deliver on it.

Farmers, facing tightened environmental rules and other challenges, have held recent protests in at least a half-dozen E.U. countries. Right-leaning parties skeptical of some climate regulations are poised for a major win in European parliamentary elections later this year. The “greenlash” is building, from France to Ireland.

“We’re being pontificated to from the top down,” said Tommy Lane, a beef farmer in Ireland, where new rules designed to reduce organic nitrogen pollution are forcing farmers to consider culling herds.

The target for 2040 is merely a recommendation from the European Commission, the E.U.’s executive branch, and must be approved by its member nations — an uncertainty, given the political climate. Countries have the right to voice concerns or set a lower target, and will begin debate next month.

Since unveiling its Green Deal in 2019, Europe has positioned itself at the forefront of the global transition, unveiling a flurry of climate-friendly policies, targets and rules. The E.U. now accounts for just seven percent of global emissions, compared to 13 percent two decades ago. The bloc also rapidly built up its wind and solar capacity to offset cutbacks in Russian gas imports.

But even those steps haven’t put the E.U. on track to reach its targets — including the first major marker, for 2030, of a 55 percent reduction in greenhouse gas emissions compared to 1990 levels. The E.U.’s climate advisory board said last month that reductions would need to “increase considerably,” and it noted the need for much more progress in areas, such as agriculture and building efficiency, where changes would likely be politically unpopular. People would need to renovate their homes in massive number to bring them up to standards, for instance.

The European regulatory approach differs substantially from that in the United States, where Congress has declined to endorse carbon taxes and climate restrictions, prompting the Biden administration to prioritize carrots — financial incentives — over sticks to boost clean energy.

Polls show that concern about climate change is higher in most major European countries than it is in the United States. But even Europeans, according to polls, tend to balk at steps that would cause a personal financial hit. According to a YouGov poll conducted last year in seven European countries, including Britain, most of those surveyed expressed opposition to increased fuel duties or higher airfare. There was widespread support, on the other hand, for government subsidies to make homes more energy efficient, or for a ban on single-use plastics.

In the draft document about the target, obtained by The Washington Post, the Commission appeared to acknowledge the backlash, saying it is “aware of the worries that some citizens and industrial actors have and some of the pushback to individual measures.”

“The imperative that this transition has to be just is at the heart of this work,” the document said. “Climate action has to take everybody along.”

While weighing its 2040 target, Europe put out a call for feedback, and it received plenty, from all sides, numbering in the thousands — from think tanks and companies and ordinary citizens. As an example, major German airline Lufthansa wrote to the Commission that it wanted the global playing field to remain “level,” including for aviation, during Europe’s green transition. A citizen from the Netherlands sketched out the opposite vision: Tax airlines, the person suggested, and use the proceeds from more expensive air travel to improve Europe’s train system.

Some people who wrote to the Commission, on the other hand, said the entire Green Deal was taking an undo social toll. One person from the Czech Republic described “bureaucratic Soviet-style interventions” that were hurting Europe while other countries refused to play their part in the climate transition.

That sentiment is helping center-right and far-right parties, who are expected to gain seats after the June vote. The European Council on Foreign Relations, in a recent policy brief, outlined how a more right-leaning parliament would have thwarted a recently-passed measure — opposed by farmers — aimed at protecting biodiversity. The brief said that a “significant shift to the right in the new parliament will mean that an ‘anti-climate policy action’ coalition is likely to dominate.”

“This would significantly undermine the E.U.’s Green Deal framework and the adoption and enforcement of common policies to meet the E.U.’s net zero targets,” the report said.

Susi Dennison, a senior policy fellow and one of the authors of the report, said that early aspects of the Green Deal — like the emissions trading scheme — felt too complicated to register with most Europeans. But more recent steps, such as the planned 2035 ban on traditional gasoline cars, are more concrete, and come at a sensitive time when Europeans are already worried about daily costs and security.

“This is the phase we’re going to: [green measures] having more impact on individual lives,” Dennison said. “That is where you’re starting to see the greenlash.”

The most obvious sign of concern comes from farmers, who have taken to the streets in multiple European countries, blaring tractor sirens in Berlin, or blocking highways outside of Paris. The motives for the protests differ slightly from country to country, but in both France and Germany, farmers were facing cuts to diesel subsidies. France’s union last Thursday called for a halt to the protests after the government made several concessions.

Still, agricultural groups say that farmers feel targeted by environmental regulation, and sense more is likely to come. The E.U. heavily subsidizes the agriculture sector, and emissions — coming from fertilizer use, manure and cow burps — have remained essentially flat for years.

That has made the sector symbolic of the tough steps ahead. Some policymakers have gone so far as to suggest that cow herds need to be reduced, and that Europeans should consume less meat.

The farm sector has pushed back. The farm association in Ireland, where farming contributes to 40 percent of national emissions, says that government policy is trying to “regulate farmers out of business.” At an event last year, the then-association president, Tim Cullinan, said that farmers wanted to play their role in dealing with climate change, but that “we will not allow farming to become the sacrificial lamb where cutting out a cultural activity is seen as a fast-track solution to reduce overall national emissions.”

Lane, the Irish farmer, and a local association leader, described in an interview how Ireland, for years, had been given an exemption from European rules on organic nitrate levels. But that exemption is now expiring, and because organic nitrogen comes from manure, the only way to deal with the declining threshold — measured in kilograms per hectare — is to obtain more land or reduce the number of animals.

“The next generation, do they want to put up with the level of uncertainty? The level of regulation?” Lane said. “To go into a career that cannot guarantee that you will remain viable for the lifetime of your career?”

Others across Europe have made the case that sticking with green policies is essential, and ultimately profitable, helping E.U. industries become global leaders in the energy transition. In addition, many multinational corporations operate in Europe, and by changing their practices to comply with E.U. emissions targets, such corporations would be more likely to clean up their operations in the United States and other countries.

Europe has also experienced a wave of severe climate disasters, including heat waves and wildfires. Sticking to most ambitions of the Paris agreement means “markedly fewer economic losses compared to grappling with the fallout of climate impacts,” said a recent report from the Climate Action Network Europe.

“We tried to stress the benefits of climate action, which are not mentioned enough,” said Olivier Vardakoulias, a CAN Europe finance and subsidies policy coordinator. “I think some things are quite disregarded in the public discourse.”