"The decision now, to pull out, this for us is something we hoped would not have happened," Cardinal Peter Turkson, president of the Pontifical Council for Justice and Peace, told reporters on Wednesday.
"It's a global public good that needs to be taken care of," he continued, speaking at a media briefing before he addressed an audience Wednesday evening at Georgetown University in Washington, D.C. on "Vatican Perspectives on Care for Creation, Economic Injustice, the Refugee Crisis, and Peace."
Also in advance of President Trump's announcement on Thursday afternoon, a U.S. bishop pressed the government to honor its commitment to the Paris climate agreement.
The Paris Agreement was an international climate accord reached in 2015 after representatives of over 150 countries met for COP 21, or the United Nations Climate Change Conference.
Countries pledged on various levels to help reduce global carbon emissions and aim to keep global temperatures from rising more than two degrees Celsius, as compared to average temperatures from the pre-industrial age, by the end of the 21st century.
Pope Francis had written his ecology encyclical Laudato Si in advance of the climate agreement, noted Bishop Oscar Cantu of Las Cruces, chair of the U.S. bishops' International Justice and Peace Committee.
It "was timed in order to urge the nations of the world to work together in Paris for an agreement that protects our people and our planet," he said. "Our Conference of Bishops has vigorously promoted the teaching of our Holy Father, Pope Francis, on care for our common home."
When the agreement was reached in 2015, Pope Francis hailed it as "historic" and said that it would require "a concerted and generous commitment" from members of the international community. Over 190 countries have signed on to the agreement.
On Thursday afternoon in the White House Rose Garden, President Trump announced that the U.S. was pulling out of the agreement, citing its detrimental effects on U.S. energy and American businesses.
"In order to fulfill my solemn duty to protect America and its citizens, the United States will withdraw from the Paris climate accord," he stated, adding that the U.S. would "begin negotiations to re-enter either the Paris accord" or conduct an "entirely new transaction on terms that are fair to the United States, its businesses, its people, its taxpayers."
The 2015 agreement was "simply the latest example of Washington entering into an agreement that disadvantages the United States to the exclusive benefit of other countries," he stated, criticizing its "draconian financial and economic burdens" including the Green Climate Fund and the "nationally determined contribution" of the U.S.
Nevertheless, Catholic leaders insisted that as a world leader, the U.S. must lead by example in taking measures to curb its pollution and carbon emissions. On Thursday, Bishop Cantu called Trump's decision "deeply troubling."
"The Scriptures affirm the value of caring for creation and caring for each other in solidarity. The Paris agreement is an international accord that promotes these values," he said.
"The impacts of climate change are already being experienced in sea level rise, glacial melts, intensified storms, and more frequent droughts. I can only hope that the President will propose concrete ways to address global climate change and promote environmental stewardship."
Catholic Relief Services, a global Catholic aid agency, said that the decision of a world power to renege on promises to cut carbon emissions and pollution could result in higher temperatures and ultimately hurt the world's poor who are the most vulnerable to climate change.
"As an international humanitarian organization, we are confronted with the realities of climate change every day and see the devastating impact on the lives of the people we serve," Bill O'Keefe, vice president for advocacy and government relations for CRS, stated on Thursday.
For instance, CRS noted, "in Bangladesh, rising sea levels are encroaching on water tables and swallowing coastal homes. In Central America, coffee farmers are losing their crops due to more frequent drought and because warmer temperatures help pests thrive."
Cardinal Turkson said on Wednesday that he respected Trump's decision but hopes for future dialogue and a change of policy.
"We will still respect the sovereign decision of any sovereign state," he said. "We just hope in this regard that even this decision will not be the last."
In February, Bishop Cantu had joined Bishop Frank Dewane of Venice, chair of the U.S. bishops' domestic justice and human development committee, and the president and CEO of Catholic Relief Services Sean Callahan in writing a letter to new Secretary of State Rex Tillerson, exhorting him to honor the U.S. commitment to the Paris agreement.
"In 2015, the United States Conference of Catholic Bishops affirmed that funding for climate change related adaptation and mitigation programs as part of the Paris agreement - especially through the GCF - is urgently needed if we are to meet our common and differentiated responsibilities for the effects of climate change," they stated. The U.S. must also effort to reduce its own carbon emissions, they added.
"The Paris agreement is a key step towards both these goals," they said.
In lecture at Boston College in the fall of 2015, Cardinal Turkson explained that, according to the encyclical Laudato Si, developed nations should shoulder a greater burden in fighting climate change than poorer, developing countries.
Pope Francis, he said, "insists that the global north has been a disproportionate consumer of creation's goods and contributor to ecological harm; therefore it must repay its 'ecological debt' to the global south."