Pope Francis, who has a strong belief in the science of climate change, called upon world leaders on Wednesday to "listen to the cry of the Earth and the cry of the poor, who suffer most because of the unbalanced ecology."

Francis and Patriarch Bartholomew I, the head of the Orthodox Christian Church, will issue a joint message to commemorate the annual "World Day of Prayer for the Care of Creation" on Friday, the Associated Press reported.

In 2015, the Pope designated Sept. 1 as "a precious opportunity to renew our personal participation in this vocation as custodians of creation," framing the preservation of the environment as a moral responsibility.

Similarly, Bartholomew—who backed Francis' 2015 encyclical on the environment, Laudato Si—once said:

"There has never been so much turmoil on our planet, but there has never been greater opportunity for communication, cooperation and dialogue. Basic human rights such as access to water, clean air and sufficient food should be available to everyone without distinction or discrimination. We are convinced that we cannot separate our concern for human dignity, human rights or social justice from the concern for ecological preservation and sustainability."

Pope Francis has long pressed for strong climate action. In May, during their meeting at the Vatican, the pontiff gifted President Trump a copy of the climate encyclical right as POTUS considered whether the U.S. should exit from the Paris climate agreement. Trump, a notorious climate skeptic who does not agree with Francis about the global phenomenon, apparently didn't take the Pope's message to heart—he controversially withdrew the U.S. from the Paris accord just a month later.