Like his predecessors Pope Benedict XVI and Pope John Paul II, Pope Francis is concerned with what some evangelical Christians call “creation care.” The following encyclical, or teaching document, is to date the most extensive and systematic statement of Catholic teaching on the natural environment. Here Pope Francis expresses his grave concern about the adverse effects of climate change on the earth’s ecosystems and on human beings, particularly poor people residing in the Third World. Addressing and attempting to mitigate these adverse effects is not only a scientific issue, Francis contends, but a moral matter.