OSAKA, Japan — Japanese Prime Minister Shinzo Abe opened deliberations at the Group of 20 summit Friday by expressing his hope of achieving “beautiful harmony” among the world leaders gathered in the city of Osaka.

But with his close ally President Trump in town, that goal may prove to be elusive. 

Behind the scenes, divisions are as deep as ever over the environmental crises facing the planet — from climate change to the deluge of plastic litter choking the world’s oceans — and frustrations are mounting that Abe is merely trying to paper over the cracks. 

The stakes were raised in the run-up to the meeting when French President Emmanuel Macron said he would refuse to sign any joint statement coming out of Osaka that failed to tackle climate change, calling it a “red line.” 

On Friday night, officials were still negotiating a text that could satisfy the Europeans on one side and the United States on the other, with no guarantee of success. 

Chairing the G-20 was always going to be a tough task for the Japanese leader. With Trump determined to keep the United States out of the Paris climate accord and his administration opposing efforts to phase out production of single-use plastics, the United States has few friends in Osaka when it comes to the environment. 

Abe has the unenviable task of trying to keep Japan’s most important ally happy while delivering on a promise to provide leadership at the G-20 on climate change and ocean plastics. The success of his efforts was hanging in the balance Friday. 

At the end of the first day of talks, Foreign Ministry spokesman Takeshi Osuga briefed the press for more than half an hour without mentioning climate change. 

Then, when pressed on whether world leaders had even raised the issue during Friday’s discussions, he said simply, “Some leaders touched upon climate change, but I will refrain from getting into details about who said what.” 

Osuga later said other leaders had not mentioned climate change but did not acknowledge any “dissent” over the issue. 

Behind the scenes, officials from participating countries known as sherpas were “working hard to achieve a positive outcome document,” he added. 

Osuga said the issue of marine plastics litter, billed before the summit as a major thrust of Abe’s presidency of the group, had not been mentioned by any of the gathered leaders Friday. 

At the past two G-20 summits, Trump refused to endorse a joint plan to combat climate change, but the other 19 leaders remained united. 

Reflecting this impasse, the G-20’s energy and environment ministers managed only a passing reference to the Paris climate accord when they met in the Japanese town of Karuizawa earlier this month, noting simply that countries that had chosen to implement the pact reaffirmed their commitment to do just that. 

The Intergovernmental Panel on Climate Change report on the effects of global warming of 1.5 degrees Celsius was likewise merely “noted” in their communique. 

On Friday afternoon, European leaders were discussing how defiantly to confront Trump on climate change, with some undecided about whether they would sign a joint statement if it didn’t include a pledge to take action. 

A top Brazilian negotiator said talks remained in flux Friday evening, adding that all sides were still working toward an agreement but not definitively predicting that a consensus could be reached. 

Speaking to reporters Friday morning, Jean-Claude Juncker, president of the European Commission, said he saw the need for “a strong statement on climate change” and couldn’t accept “a watering down” of what had been said at the last G-20 meeting, in Buenos Aires last year.

Asked whether he had a “red line,” like Macron, Juncker said, “My lines don’t have colors.”

Japanese officials believe it is better to have some kind of consensus, even if it is relatively mild, than another document that sets 19 parties on one side and the United States on the other.

But environmental groups fear that Abe and the G-20 could produce an anodyne communique that fails to grasp the seriousness of the crisis facing the planet. 

They accused Japan of showing “no ambition, no sense of urgency and a lack of political will.” 

“It is not only unacceptable, but it also undermines global efforts to fight this pressing issue,” said Kimiko Hirata, international director of Kiko Network, a Japanese nonprofit working to prevent climate change, speaking on behalf of a coalition of such groups. 

Abe has stressed the role of innovation in tackling climate change and marine plastic litter in ways that do not undermine economic growth. When it comes to energy, he has focused on developing hydrogen as a fuel and on carbon capture, utilization and storage.

But environmental groups say that such technologies are unlikely to be economically viable in the near future and that this strategy lacks the urgency required to reduce greenhouse gas emissions. 

G-20 countries committed in 2009 to phase out subsidies for fossil fuels, but a report this month showed that subsidies have actually increased in recent years; subsidies to coal plants, for instance, have doubled in the past three years. 

Meanwhile the United States, backed by the U.S. plastics industry, has blocked efforts to phase out production and consumption of single-use plastics and to draw up a legally binding treaty to tackle the marine plastic litter problem, environmental groups say. Accordingly, in Karuizawa, ministers agreed only that countries would take “voluntary” action on the issue.

“Japan is again hiding behind Trump,” Hirata said. “It was trying to get a stronger agreement at the G-20 on marine plastic. But Japan sees the Trump administration as an important ally, and that puts an agreement in danger.”

In his opening remarks, Abe was referring to the new imperial era, called Reiwa, or “beautiful harmony,” which began with the coronation of Emperor Naruhito this year.