ROME — Ahead of a Vatican and UN-sponsored summit on the environment set for Tuesday, some of America’s leading climate change and global warming skeptics assembled in Rome on Monday to press the case that climate change concerns are “non-issues.”

Members of the Heartland Institute, a libertarian public policy think tank based in Chicago, held what they called a “prebuttal” of a Rome conference to be put on by the Vatican and the United Nations on the moral dimensions of climate change and sustainable development, titled “Protect the earth, protect humanity.”

The counter-event also comes ahead of a highly anticipated encyclical letter from Pope Francis on the environment, expected to be released in early summer.

“We’re here to prevent the pope from making the mistake of having the UN as an advisor, because he won’t be getting the whole picture,” said Jim Lakely, a Heartland spokesman, in opening remarks.

Lakely told the gathering that global warming doesn’t have a basis in fact because, he claims, the United Nation’s data on climate change has been inaccurate since 1990.

Instead, he defined global warming as “the combination of abandoning the scientific method to analyze climate change, stacking the deck in favor of climate alarmism, and, frankly, outright corruption.”

Lakely said the pope would be making a great mistake to put his trust in the United Nations because it’s “not credible on the science.” He also charged that the UN advocates policies, particularly in the energy sector, that would keep the poor in even greater misery.

Joseph Bast, director of the Heartland Institute, said there’s no empirical evidence – “the only kind that matters” – that proves that the use of fossil fuel is causing global warming.

“I urge Pope Francis to protect the poor by rejecting the policies that try to undercut the abundant, reliable, affordable energies from fossil fuel,” Bast said.

Elisabeth Yore is an international children’s rights attorney who also participated in Monday’s news conference at the Hotel Columbus, about a block away from St. Peter’s Square. She said she’s “deeply troubled” by recent statements from the Vatican’s Pontifical Academy for Sciences.

When the academy announced the Vatican-UN summit, it said the event’s objective is to produce “a joint statement on the moral and religious imperative of sustainable development, highlighting the intrinsic connection between respect for the environment and respect for people – especially the poor, the excluded, victims of human trafficking and modern slavery, children, and future generations.”

Yore called that “preposterous,” saying there’s no connection between climate change and human trafficking.

“This nexus between human trafficking and climate change is … deceptive and infinitely damaging to the cries of human trafficking victims around the world,” she said.

“This statement places the real human crisis of modern slavery on the same line of the manufactured one of climate change,” Yore said, adding that she has worked with Oprah Winfrey to promote children’s rights and to fight human exploitation.

Yore argued that trafficking is growing for other reasons, such as war and sex-selective abortions.

“Abortion, not climate change, is fueling the industry of human slavery,” she said.

Yore also blasted UN advisor Jeffrey Sachs, who was at the Vatican on April 18 to promote the global body’s Sustainable Development Goals, to be signed by 193 heads of state in September. Predicted to be the largest meeting of its kind for the number of presidents and prime ministers in attendance, the assembly will open with an address by Pope Francis.

According to Yore, Sacks has spent his career sounding the alarm that the world is overpopulated and that fertility rates must be lowered. She charged that his willingness to support abortion, sterilization, and contraception is against Catholic teaching.

“I find it incomprehensible that the Vatican would be misled into thinking that the UN and the Vatican share common solutions,” she said. “The Church welcomes children as a gift from God, when the United Nations and Sachs want to limit the number of children.”

Marc Morano, publisher of an eco-news center called ClimateDepot, said that at the end of the day, “no one cares” what Francis and the Vatican think about climate science.

However, he said, penning an encyclical that endorses a UN treaty such as the sustainable development goals would be “confusing to many Catholics around the world,” who could be led to believe that UN positions on climate change and global warming are now part of Catholic doctrine.

Engineer Harold Doiron, a former NASA scientist, said he’s concerned about Pope Francis’ willingness to accept that carbon dioxide emissions are causing massive environmental damage, a position he claims is not supported by research.

“Houston, we do not have a problem,” Doiron quipped.

A member of the team that developed the Apollo Lunar Module landing software, Doiron said that “using the same scientific method that put the man on the moon,” he and his colleagues have concluded that “there’s no global warming.”

Heartland Institute spokesmen said they’re attempting to schedule a meeting with Vatican officials, or even possibly attending the environmental conference, being held at the Vatican’s Casina Pio IV.

In the meantime, Un secretary general Ban Ki-moon will give the opening remarks alongside Ghana’s Cardinal Peter Turkson, president of the Vatican’s Pontifical Council for Justice and Peace, tapped by Francis to help him draft his encyclical.

Pope Francis is not on the schedule for the conference, and although a private audience between the pontiff and Ki-moon is rumored, it hasn’t been confirmed.