Pope Francis said on Monday that he was writing a follow-up to his landmark 2015 encyclical on the protection of the environment and the dangers of climate change "to bring it up to date".
He made the surprise announcement in a brief, unprepared addition in a speech to a group of lawyers from Council of Europe countries.
In 2015, Francis wrote Laudato Si (Praised Be), a major document on the need to protect the environment, face the dangers and challenges of climate change and reduce the use of fossil fuels. An encyclical is the highest form of papal writing.
"I am writing a second part to Laudato Si to bring it up to date with current problems," Francis told the group, without elaborating.
The encyclical, which made Francis a hero to many climate activists, was seen to have influenced the decisions taken later that year at the Paris climate conference that set goals to limit global warming.
At the time it was issued, some conservative Catholics allied with conservative political movements and corporate interests fiercely criticised the pope for backing the opinion of a majority of scientists who said global warming was at least partly due to human activity.
U.S. climate envoy and former secretary of state John Kerry told Reuters in an interview in June after meeting the pope that the encyclical had a "profound impact" on the Paris conference.
In his comments on Monday, Francis did not specify what form the second part of Laudato Si would take, when it would be released or how it would elaborate on the original.
In the eight years since the document was published, the world has seen an increase in extreme weather events such as more intense and prolonged heat waves, more frequent wildfires and more severe hurricanes.
Last year, a senior Vatican official whose brief includes the environment said such events had become the "new normal" and had shown that the time for climate change denial and scepticism was over.
