VATICAN CITY (Reuters) - Denying climate change or being indifferent to its effects are “perverse attitudes” that block research and dialogue aimed at protecting the future of the planet, Pope Francis said on Thursday.

Pope Francis arrives to welcome Austrian President Alexander Van der Bellen before a private audience at the Vatican, November 16, 2017. REUTERS/Aberto Pizzoli/Pool

Francis, a strong defender of environmental protection, made his comments in a message to ministers meeting in Bonn to work out a rule book for implementing the 2015 Paris Agreement, which

aims to move the world economy off fossil fuels.

“We have to avoid falling into these four perverse attitudes, which certainly do not help honest research and sincere and productive dialogue on building the future of our planet: negation, indifference, resignation and trust in inadequate solutions,” he said.

Francis called climate change “one of the worst phenomena that our humanity is witnessing”.

He praised the Paris accord, which U.S. President Donald Trump said the United States planned to leave, for indicating what he called a “clear path of transition towards a model of economic development with little or no carbon consumption”.

The United States is the only country out of 195 signatories to have announced its intention to withdraw from the accord, which aims to cut emissions blamed for the rise in temperatures.

Trump announced the decision in June shortly after visiting the pope. At the time, a Vatican official said the move was a “slap in the face” for the pope and the Vatican.

Before his election, Trump labeled climate change a “hoax”.

The pope has sided with those who believe global warming is at least partly man-made and has praised scientists who are working to keep the earth’s temperature under control.

Last September, he said the spate of hurricanes at the time 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.