Two officials from the U.S.-based Maryknoll Office of Global Concerns said the position taken by the alliance serves as a call to the world to ensure that developed countries take definitive steps to significantly reduce their greenhouse gas emissions.

"The real debate is over a political versus a legally binding document," Maryknoll Sister Ann Braudis, who co-chairs the UN NGO Committee on Sustainable Development, told Catholic News Service in an e-mail.

She said the United States, during an afternoon news conference, promised to seek meaningful reductions in greenhouse gas emissions while working to make the expected political agreement a legally binding one.

The same day, the U.S. Environmental Protection Agency announced it had determined greenhouse gases are endangering people's lives and must be regulated. The announcement was timed to send a message to the UN conference that the White House was ready to act on global warming even without congressional action.

Braudis's Washington-based colleague, Kathy McNeely, told CNS in a telephone interview that the broad network of faith-based nongovernmental organizations on hand in Copenhagen, including Caritas Internationalis and the Catholic International Co-operation for Development and Solidarity, are taking the opportunity to press the need for a legally binding climate agreement because the future of the world's poorest nations is at stake.

"Our message is a moral message," McNeely said. "The United States has very smart people negotiating for them as do some of the other countries of the North, and they should be able to figure out how to best protect the most vulnerable countries."

More than 100 world leaders were expected at the two-week summit, driving hope that a significant deal could be reached to replace the existing UN Kyoto Protocol that limits carbon-based emissions. The protocol runs through 2012.

Nearly three dozen representatives of Catholic aid and development organizations were in Copenhagen to deliver a common message: action must be taken immediately to ease the impact of global climate change on poor and vulnerable people because they already are being adversely affected by drought, flooding and rising sea levels brought on in part by the high levels of greenhouse gas emissions from more developed countries.

Before the world gathering, religious leaders offered their prayers and called for responsible actions on behalf of the Earth.

Pope Benedict XVI, speaking at his noon blessing at the Vatican Dec. 6, said protection of the environment requires more sober lifestyles and a rediscovery of the "moral dimension" of development. He also said he hoped the Copenhagen conference would identify policies that "respect creation and promote a co-operative development founded on the dignity of the human person and oriented toward the common good."