Another goal, says a statement on a Vatican website, is to highlight "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."
In addition to the keynote speech by Ban, participants will hear from Jeffrey Sachs, a prominent American economist and director of the Earth Institute at Columbia University. Church sources said that leading scientists in the climate-change field will also take part.
Also addressing the conference will be Cardinal Peter Turkson of Ghana, a top Vatican official who is leading the drafting process of Francis' encyclical on the environment, which is expected to come out in June or July.
An encyclical is one of the most authoritative documents a pope can issue, and church sources say this one has been the focus of intense lobbying by Catholics, especially American conservatives who believe that climate change is being overhyped or that human activity is not a factor and that remedies may do more harm than good.
Others simply believe that Francis — who signaled that environmental protection would be a hallmark of his papacy when he took the name of the unofficial patron saint of ecology, Francis of Assisi — should not be weighing in on issues that touch on technical and scientific matters that some contend are still debatable.
Francis "is an ideologue and a meddlesome egoist," Maureen Mullarkey wrote in an especially trenchant column at the conservative journal First Things about what she called the pope's' "premature, intemperate policy endorsements" on the environment.
Other Catholic conservatives have delivered similar critiques, while some, such as author George Weigel and Princeton political philosopher Robert George, have sought to downplay the import of any statements the pope might make on the environment.
The Vatican's Council for Justice and Peace, which is led by Turkson and is spearheading the drafting of the encyclical, has been a special focus of lobbying by climate-change skeptics who hope to influence the final version, church sources say.
Liberals and environmentalists, as well as the Obama administration, have embraced the pontiff's "green" agenda and are hoping Francis will give support to their side.
Francis himself does not appear to have heeded the critics so far.
Though his two immediate predecessors, Pope Emeritus Benedict XVI and St. John Paul II, also spoke out strongly on the Christian duty to protect the environment, Francis has done so more frequently and forcefully, and at a time when climate change has become a hot-button political issue.
"(I)t is man who has slapped nature in the face," Francis told reporters in January. "We have in a sense taken over nature," he said, adding that he believed global warming is "mostly" the result of human activity. In February, he said "a Christian who does not protect creation … is a Christian who does not care about the work of God."
Francis has also expressed disappointment in the last round of international negotiations to reduce greenhouse gases, calling them "nothing much." He has said he wants his encyclical to come out in time to influence the next round, set for Paris in November.
This month's Vatican summit on the environment appears to be another effort to try to press the pope's agenda, and it's a topic that's likely to remain on the front burner as Francis prepares to make his first U.S. visit in September, which will include an address to the U.N. General Assembly in New York.