Pope Francis has prayed for the success of the United Nations' COP21 climate change summit that is currently underway in Paris. The Pope was speaking on Sunday following the recitation of the Angelus in St Peter’s Square on Sunday. According to Vatican Radio, the Pontiff said he was following the conference closely and it reminded him of a question he posed in his encyclical Laudato Si': “What kind of world do we want to pass on to those who come after us, to the children who are growing up?" He went on to say, "For the sake of the common home we share and for future generations, every effort should be made, in Paris to mitigate the impact of climate change and, at the same time, to tackle poverty and to let human dignity flourish." The Pope added: "Let us pray that the Holy Spirit will enlighten all who are called to take such important decisions and give them the courage to always use as their criterion of choice the greater good of the human family." Pope Francis also made reference to the 50th anniversary of a joint declaration between Pope Paul VI and Ecumenical Patriarch Athenagoras, which took place signed on the eve of the conclusion of the Second Vatican Council, on December 7, 1965. He said the timing of the anniversary was important, coming just before the Year of Mercy gets underway on Tuesday. The Pope also paid tribute to three priests killed in hatred of the faith, who were beatified in Chimbote, Peru, on Sunday.