Pope Francis summoned scientists, government officials and religious leaders to a villa in the manicured Vatican Gardens on Tuesday as he stepped into the heated climate-change debate. “Climate change is a defining issue of our time,” United Nations Secretary-General Ban Ki-Moon told attendees at the Vatican conference. “It is a moral issue, it is an issue of social justice, human rights and fundamental ethics.” The conference, which is being held under the auspices of the Pontifical Academy of Sciences, precedes a papal encyclical scheduled for publication in June. The encyclical, a letter to the world’s bishops but with broader resonance because of the pope’s moral and political authority, will aim to influence a UN summit in Paris at the end of the year, at which nations may pledge to […]