The Dutch government on Monday appealed against a landmark 2015 court ruling which ordered it to slash greenhouse gases by a quarter by 2020.
"The current government is already extraordinarily active in terms of climate," lawyer Bert-Jan Houtzagers told the Hague Appeals Court.
Three years ago some 900 Dutch citizens led by environmental rights group Urgenda won a landmark court case as they sought to force a national reduction of emissions blamed for global warming.
Urgenda, which brought the case in April 2015, said it wanted the government to reduce greenhouse gas emissions by 40 percent over 1990 levels by 2020.
The court found in favour of the rights group exhorting the government to do more in a ruling handed down a few months ahead of the Paris Climate Agreement.
The global Paris deal sets out measures to reduce greenhouse gas emissions to prevent temperatures rising by more than two degrees Celsius.
The Dutch government's appeal of the 2015 court ruling, questions in particular the "extent of judges' control over the future policies of the state".
Activists said Monday the Dutch state "must do more" to reduce greenhouse gas levels.
"It is its duty to protect its citizens," Urgenda's lawyer Koos van den Berg told the judges.
"Global warming is a fact, not a fable," Van den Berg added, saying there were major risks for citizens if the Netherlands does not start preserving the climate at "top speed".
A ruling in the case is expected in the coming months.
The Dutch government this month said it intended to close two of its oldest coal-fire plants by 2025.
Three remaining coal plants will have to close by 2030, with the Netherlands being committed to reduce its carbon dioxide emissions by 49 percent by then.
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