United Nations — "We must break the addiction to coal," U.N. Secretary General Antonio Guterres said at U.N. Headquarters in New York on Monday, on the day that two lawmakers in Sweden nominated teen climate activist Greta Thunberg for the 2020 Nobel Peace Prize.

The U.N. chief has called for a reduction of coal before, but it was clearer than ever that the top world diplomat is sharpening his message and calling for action, several diplomats at the meeting told CBS News.

Guterres spoke to a coalition of nations called the U.N. Group of Friends on Climate and Security, initiated by Germany along with the Pacific state of Nauru in Micronesia, which formed the group in 2018 to move the climate agenda forward. Monday's meeting was co-chaired by France and Morocco.

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France, the driver behind 2015 Paris climate agreement — from which the Trump administration began its withdrawal process — will also host a world conservation congress in June.

At the event on Monday, France's U.N. Ambassador Nicolas de Riviere said: "In 2019, we witnessed the ravages of climate inaction: tropical cyclones, wildfires, cities asphyxiating under clouds of smoke and heat waves and we know that what 2019 is only the weakest version of what is yet to come if we do not choose to act now."

Guterres said 70 nations have committed to becoming carbon neutral by 2050, including the European Union, but he noted that these countries represent less than one-fourth of global emissions.

"Yet at a time when we should be phasing out fossil fuels, we are still seeing too many national energy plans dependent on coal and new coal plants being planned," he said.

U.N. Secretary General Antonio Guterres CBS News

More stern than in past talks, Guterres said that the world has not begun to "gain traction on ending subsidies for fossil fuels," adding that subsidies increased last year.

"COP25 was a disappointment," Guterres said, referring to the U.N. climate conference that ended in with little progress last December.

"The biggest emitters have a responsibility to lead the way — yet the political signals are worrisome," he said, "we are still clearly lagging behind in putting a price on carbon in most of the world."

As part of a shift to a more aggressive climate stance, Guterres announced a new Special Envoy for Climate Action and Finance, Mark Carney, the former Bank of England governor, who will begin work next month to engage business leaders to disclose climate risk.

"We must do everything we can to increase the number of private banks that align with net-zero emission commitments by 2050, and incorporate climate risk and carbon pricing in their investments, Guterres added.

His point was further underscored, he said, because the World Meteorological Organization reported that 2019 was the second hottest year on record, and that ocean heat content is at a record level.

The U.N. will be sponsoring a May conference on sustainable transport and a June oceans conference in order to the strengthen U.N. push on climate, with the hope that the next major U.N. climate summit, in Glasgow in November, is more successful than the last one.

The U.N. chief concluded: "I count on you not only to recognize our predicament, but to lead our way out of it with steps that can point the way to clean, green growth, a just transition, and prosperity and stability for all."