U.N. Secretary General Antonio Guterres is warning the world is "in deep trouble with climate change."
Speaking on the first full day of two weeks of climate talks in Poland Monday, Guterres said it is "the most important gathering on climate change since the Paris Agreement was signed."
He called on the nearly 200 countries represented in Katowice to take the issue seriously and commit to the course of action agreed to in Paris in 2015.
Signatories to the landmark 2015 Paris Accord pledged to cut greenhouse gas emissions and limit the rise in global temperatures to less than two degrees Celsius by 2030.
"I remind all Parties that this is a deadline you set for yourselves and it is vital you meet it," Guterres added.
Citing bleak recent reports, including one from the U.N. expert climate panel in October, Guterres noted devastation from hurricanes in Barbuda and Dominica, which he called "heart-breaking," but also "preventable."
President Donald Trump is pulling the U.S. out of the Paris agreement because of what he says is the economic damage the treaty's provisions would cause.
Trump is a promoter of fossil fuels and nuclear power and has proposed renegotiating the Paris Accord — an idea many dismiss as impractical.
Host country Poland is expected to propose what it calls a "just transition" for the oil, gas and coal industries to ease the financial blow from the move away from such polluting sources of energy.
But nations more immediately threatened by climate change, including Fiji, whose prime minister, Frank Bainimarama, served as president of last year's climate conference, urged developed nations to act now to save the planet.
"Or, God forbid, (we) ignore the irrefutable evidence and become the generation that betrayed humanity," Bainimarama said.
Meanwhile, oil giant Royal Dutch Shell announced Monday it is setting a series of short-term goals for cutting carbon emissions.
Shell had been facing criticism from investors and others for only establishing what they say were long-term plans to cut emissions by 2035 and 2050.
The company says meeting the goals sooner will be tied to Shell executive pay.
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Details are to be announced but are likely to include a reformulation of Shell gasoline.
"When it comes to meeting the demands of the Paris Agreement on climate change, we believe it is necessary to strengthen partnerships between investors and their investee companies to accelerate progress toward reaching such an ambitious common goal," Shell's Chief Investment Officer Peter Ferket said.