Papal encyclicals have been an engine for social change since Pope Leo XII wrote the encyclical, Rerum Novarum, in 1891.  

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Pope Leo XIII was responding to injustices created by the Industrial Revolution. This tradition continued with Pope Pius XI's Quadragesimo Anno in 1931 as the Holy Father challenged systemic inequalities underlying the Great Depression. In the mid-twentieth century, St. John XXIII modernized Catholic Social Teaching with Mater et Magistra in 1961 and then, under the threat of nuclear war, St. John XXIII released Pacem in Terris in 1963.

 

These documents highlighted core aspects of Catholic Social Thought, which includes the dignity of the human person, right to private property, the common good, subsidiarity, solidarity and the universal destination of goods. Blessed Paul VI applied these values to questions of authentic social and economic development in Populorem Progressio in 1967.  

 

Pope Francis, as did his predecessors in their own times and facing challenges of their day, has responded to today's environmental crisis by placing questions of "care for our common home" squarely within the tradition of Catholic Social Teaching, adding magisterial authority and imperative to sound ecological stewardship.