Veerabhadran Ramanathan is a distinguished professor of atmospheric and climate sciences at the Scripps Institution of Oceanography at the University of California, San Diego, and an “ordinary academician” at the Pontifical Academy of Sciences in Rome. His work is expected to have contributed to Pope Francis’ encyclical.

Riccardo Cascioli is the author of Lies of the Environmentalists and has criticized Pope Francis’ involvement in climate change, which Cascioli sees as a wedge into changing Catholic doctrine about the sanctity of life. He is also the editor of La nuova Bussola Quotidiana, an Italian Catholic news and opinion site.

Marc Morano is executive director of ClimateDepot.com and communications director at Committee for a Constructive Tomorrow, a conservative think tank in Washington that is skeptical of man-made climate change. He has been critical of Pope Francis’ involvement in climate change issues and his reliance on United Nations climate change data.

Catholic Climate Covenant is an umbrella environmental and climate change advocacy organization that includes multiple Catholic organizations, such as the U.S. Conference of Catholic Bishops. It organizes public letters to policymakers on environmental topics and provides training on lobbying.

The Franciscan Action Network is a Washington, D.C.-based grassroots network of Franciscan clergy and “Franciscan-hearted” laypeople who focus on peacemaking, climate care, social justice and poverty, among other issues. Patrick Carolan is executive director.

Thomas Peters started and runs the American Papist blog and works with Catholic Vote. He speaks about Catholicism and politics, pro-life issues and pro-family activism, the future of social media and youth activism.

Karen Armstrong, a former Catholic nun, is an authority on the Abrahamic religions and author of many books on the subject. Her most recent book is Fields of Blood: Religion and the History of Violence.

Tina Beattie is a professor of Catholic studies at the University of Roehampton in London. She focuses her research on the relationship between the Catholic tradition and contemporary culture with an emphasis on gender, sexuality, and reproductive ethics. She also studies Catholic social teaching and women’s rights, and theology and the visual arts.

Charles E. Curran is a professor of human values at Southern Methodist University. Curran teaches fundamental moral theology, social ethics, role of the Church as a moral and political actor in society, and Catholic moral theology.