More than three million people are without power amid high winds and flooding, as fears grow over storm surges.
“Those who deny it [climate change] should go to the scientists and ask them,” the pontiff said on Monday during an in-flight press conference on the return leg of a five-day Colombia trip. “They speak very clearly.”
As his charter plane flew over some of the recently devastated areas en route to Rome, Francis added: “I am reminded of a phrase from the Old Testament, I think from the Psalm: ‘Man is stupid, he is stubborn and he does not see.'”
The pope’s comments came as Hurricane Irma, one of the most powerful Atlantic storms in a century, caused widespread destruction across the French Caribbean islands, Cuba, Dominican Republic, Puerto Rico, Haiti and the US state of Florida. At least 38 people have been killed so far from the Category 5 superstorm.
Meanwhile, Hurricane Katia bore down on the east coast of Mexico, leaving at least two dead.
Far out in the Atlantic, Hurricane Jose, a Category 2 storm, having brushed past the Caribbean also poses a potential threat to the US east coast.
Last month, Hurricane Harvey, one of the worst storms to hit the US mainland in 12 years, led to unprecedented flooding in the southern US state of Texas.
Francis is one of the world’s most high-profile campaigners on environmental issues, actively supporting efforts to combat climate change and its consequences.
He said individuals and politicians had a “moral responsibility” to act on advice from scientists, who had clearly outlined what must be done to halt the course of “catastrophic” warming.
“These aren’t opinions pulled out of thin air,” he said. “They are very clear. They [world leaders] decide and history will judge those decisions.”
Recalling last month’s news that a ship crossed the Arctic without an icebreaker for the first time, Francis said: “We can see the effects of climate change, and scientists clearly say what path we should follow.”
While regularly criticising politicians, the pope has made caring for the environment a hallmark of his papacy.
He wrote an entire encyclical (a letter from the pope disseminated to the bishops of the Church) about how the poor in particular are most harmed when multinationals move in to exploit natural resources.
During his visit to Colombia, Francis spoke out frequently about the need to preserve the country’s rich biodiversity from overdevelopment and exploitation.
Among world leaders, US President Donald Trump has repeatedly made a case sceptical of the existence of climate change.
In June, Trump pulled the United States out of the Paris Agreement, which binds countries to national pledges to reduce greenhouse gas emissions.