The encyclical letter Laudato Si is available here on the Vatican website. Pope Francis mentions the gathering on his native continent:
167. The 1992 Earth Summit in Rio de Janeiro is worth mentioning. It proclaimed that “human beings are at the center of concerns for sustainable development”.[Rio Declaration on Environment and Development (14 June 1992), Principle 1] Echoing the 1972 Stockholm Declaration, it enshrined international cooperation to care for the ecosystem of the entire earth, the obligation of those who cause pollution to assume its costs, and the duty to assess the environmental impact of given projects and works. It set the goal of limiting greenhouse gas concentration in the atmosphere, in an effort to reverse the trend of global warming. It also drew up an agenda with an action plan and a convention on biodiversity, and stated principles regarding forests. Although the summit was a real step forward, and prophetic for its time, its accords have been poorly implemented, due to the lack of suitable mechanisms for oversight, periodic review and penalties in cases of non-compliance. The principles which it proclaimed still await an efficient and flexible means of practical implementation.
Good ideas emerged, but political leaders have been slow to act, with the occasional local exceptions.