Theology and ethics connected with climate change have grown in the past decade and Catholic leaders have been endorsing the changes. In 1996, Pope John Paul II spoke to the European Bureau for the Environment saying:
We face a fundamental question … both ethical and ecological … How can one prevent disasters that destroy the environment and threaten all forms of life?
Pope Benedict XVI, used these words in his 2007 World Day of Peace Message:
humanity … must be increasingly conscious of the links between natural ecology, or respect for nature, and human ecology.
Cardinal Martino said in his closing address to the 2007 Roman Seminar on Climate Change and Development:
This seminar deepens doctrinal reflection as Gospel meets life in society … the Gospel is always new, adapting as historical conditions change.
But beyond that were the statements and actions of Pope Benedict himself. He mentioned environmental concerns no less than seven times in connection with World Youth Day.  Speaking on his arrival at Barangaroo, he said:
Perhaps reluctantly we come to acknowledge that there are also scars which mark the surface of our earth: erosion, deforestation, the squandering of the world’s mineral and ocean resources in order to fuel an insatiable consumption. Some of you come from island nations whose very existence is threatened by rising water levels; others from nations suffering the effects of devastating drought. 
The Australian bishops’ 2005 Position Paper specifically presented a set of principles for judging climate change both locally and globally. 
 See John L Allen Jr at http://www.ncrcafe.org/node/2023.
 Australian Catholic Bishops’ Climate Change Conference Nov 2005 www.catholicearthcareoz.net. Catechism of the Catholic Church, Nos. 2422–23, 198I, 2403, 2415; Compendium Nos. 26, 170, 454.
The greatest mark of respect for climate scientists, climate change economists and political decision makers, and for the development of the Catholic faith itself, is to learn the language of climate change and the ways of scientific argument.
Jesus condemned the Pharisees for neglecting the weightier matters of the Law. The modern church must address matters of substance, and climate change is the paramount issue that the human family must act on now to secure its future in God’s creation.
Christian beliefs can help people to identify the central values they bring to the climate change issue. Faith can be a source of courage to help people to confront the changes needed in their individual and community lifestyles, and the urgency of the need for change. Faith-based learning and motivation can help Christians, and Catholics in particular, make a four-part response to climate change:
• to be truth-tellers
• to be spiritual visionaries
• to be just and compassionate
• to be social activists.
Catholics can choose to challenge – both to be assertive and to make judgments regarding climate change. They can assert the positive role of Earth in the Christian story – salvation, revelation, incarnation, sacramental signs, mysticism and the promise of life to the full and fulfilment for all creation.
Scripture presents the language of prophecy as the voice of God. In our times, Earth has shown itself as loudly prophetic. In devastating New Orleans, Hurricane Katrina was prophetic in showing the consequences of human arrogance – local arrogance in clearing the mangroves and cutting canals, which opened the city to disaster; global arrogance in increasing greenhouse gases that heat shallow waters like the Gulf of Mexicoand increase the intensity of hurricanes. Other voices of prophet Earth are the melting of heat-reflecting ice in the Arctic waters; the rapid decline of glaciers in the Himalayas and Andes, which feed rivers that support billions of people; the melting of land-based ice sheets in the Antarctic; and droughts in Australia. Earth’s prophetic messages are a constant source of prayerful reflection.
A strong Catholic moral position linking climate change and holistic sustainable development was presented in 2007 by Archbishop Migliore, speaking at the UN as theVatican’s official representative:
While the duty to protect the environment should not be considered in opposition to development, it must not be sacrificed on the altar of economic development. My delegation believes that, at its core, the environmental crisis is a moral challenge … It is not hard to see how issues of environmental protection, models of development, social equity and each one’s share of the responsibility to care for the environment are inextricably intertwined.
 Archbishop Celestino Migliore, address at the 15th session of the United Nations Commission on Sustainable Development, 10 May 2007.