A bruised Pope Francis smiles during his visit to the Sanctuary of St. Peter Claver, in Cartagena, Colombia on Sunday. Picture: Alessandro Di Meo/Pool via AP

Rome - A passage from the Bible's Old Testament that dismisses men as "stupid" is the best way to describe deniers of climate change, according to Pope Francis.

"Why are we waiting to acknowledge the effects of climate change?" Francis asked reporters on his flight back from Colombia. "I am reminded of a phrase from the Old Testament, from the Psalm: 'Man is stupid.'"

Quotes from the pope's in-flight press conference, which wrapped up his September 6-11 trip to the Latin American country, were published by Italy's ANSA news agency and several other media outlets.

"Those who deny [climate change] should go to scientists and ask them," Francis said. "They speak very clearly, scientists are precise. We can see the effects of climate change and scientists clearly say what path we should follow."

Calling on "everybody [...] from politicians downwards" to take responsibility and act, the pope said climate change "is something we cannot play with, it is very serious."

Pope Francis said the recent spate of hurricanes should prompt people to understand that humanity will "go down" if it does not address climate change and history will judge those who deny the science on its causes.

"If we don't turn back, we will go down," Francis told reporters. 

Francis strongly backed the 2015 Paris agreement on reducing global warming, from which the United States withdrew this year.

Francis spoke as hurricane Irma pounded central Florida as it carved through the state with high winds, storm surges and torrential rains that left millions without power, ripped roofs off homes and flooded city streets.

Francis was asked about recent hurricanes, including Irma and Harvey, and if political leaders who do not want to work with other countries to stem global warming should be held morally responsible for future effects on the planet.

"All of us have a responsibility, all of us, small or large, a moral responsibility. We have to take it seriously. We can't joke about it," he said. "Each person has their own. Even politicians have their own."

Ahead of the Paris summit in 2015, Francis wrote a major encyclical, or papal letter, on the care of the environment which backed the gradual elimination of fossil fuels to stem global warming.

The accord, agreed on by nearly 200 countries, aims to cut emissions blamed for global warming. The United States committed to reducing its own by 26 to 28 percent, compared with 2005 levels, by 2025. 

US President Donald Trump withdrew from the Paris agreement shortly after visiting the Vatican in May. The Vatican had urged him to stay in the accord.

A Vatican official said at the time that the US move was a "slap in the face" for the pope and the Vatican. 

Reuters and dpa