US website The Daily Caller has reported that Al Gore is impressed with the Pope's stance on the environment.
Speaking at an event at the University of California, he said: "I think Pope Francis is quite an inspiring figure really."
"A phenomena. I've been startled with the clarity of the moral force that he embodies."
"Well I've said publicly in the last year, I was raised in the Southern Baptist tradition, I could become a Catholic because of this Pope. He is that inspiring to me.
"And I know the vast majority of my Catholic friends are just thrilled to the marrow of their bones that he is providing this kind of spiritual leadership."
The comments come as the Holy Father prepares to issue a letter on global warming, where he is expected to say the burning of fossil fuels for energy is wrong and praise decarbonising the world's economies.
It has been reported that a document from a meeting Pope Francis had with academics and world leaders spoke of how fossil fuels have taken a toll on human life.
"Market forces alone, bereft of ethical values, cannot solve the intertwined crises of poverty, exclusion, and the environment," the Vatican document read.
"The move to a sustainable world will not be cost-free for all: the options we face are not 'win-win'."
The United Nations (UN) has joined forces with the Vatican to encourage countries to agree a global climate change treaty when delegates meet in December in Paris.
The UN Secretary General Ban Ki-Moon has called this "an urgent moral imperative."
"Science tells us we are far off track from reducing global emissions sufficient to keep global temperature rises below 2°C. We are currently on course for a rise of 4-5° C.
"That would alter life on Earth as we know it."
