In his much anticipated speech at the United Nations headquarters to be delivered Friday, Pope Francis will likely call on the countries of the world not to abandon those who are, in any sense, in the peripheries. A source familiar with the United Nations has told CNA the Pope intends to speak on behalf of the marginalized, but also the elderly and — indirectly — the children at risk of being aborted. The Sept. 25 speech falls during the week of celebration of the 70th anniversary of the United Nations. The occasion will be the largest gathering of heads of state in the history of the U.N., with representatives of 170 countries present. For this reason, CNA’s source does not anticipate that the Pope will tackle the issue of abortion in harsh terms. Rather, he will allude to it by speaking of the idea that “no one must be left alone.”   This choice is part of the Holy See’s longstanding diplomatic effort to counter the introduction of the right to abortion in the charters and declarations of the United Nations. The source said “a direct mention could exacerbate tempers in the ongoing discussion,” while an allusion “might achieve the goal without generating any opposition to the teaching of the Church.”   However, Pope Francis’ speech will be complex and will deal with a variety of issues.   According to CNA’s source, Pope Francis will begin with praise for the United Nations’ work during the past 70 years and will deliver his congratulations for the institution’s anniversary, reminding the United Nations of its first goal of achieving peace and security. Among the issues the Pope will likely address is nuclear non-proliferation. The Holy See is a founding member of the International Atomic Energy Agency, and historically the Holy See has worked to foster the peaceful use of the nuclear energy, but has always opposed the production of nuclear weapons. Recently, the Holy See has pushed an agreement among nations that focuses on the use of nuclear energy for positive social development.   Pope Francis’ U.N. speech will likely also address environmental issues, following up on his 2015 encyclical Laudato si'.   Another source at the United Nations told CNA that the encyclical has had “an enormous impact.” “I see people who cite the encyclical, and not just the first lines, but the more profound lines, carefully chosen,” the source added.   The Pope will urge the nations to find an agreement at the upcoming 2015 United Nations Climate Change Conference in Paris, which will include the 21st Conference of the Parties to the U.N. Framework Convention on Climate Change.