Pope Francis on Tuesday met United Nations secretary general Ban Ki-moon at the Vatican, where Ban was due to address an ecology summit centred on the issue of climate change.
Francis and Ban's 30-minute meeting took place in the Vatican gardens. Later, Ban was due to open the 'Protecting the Earth' conference organised by the Pontifical Academy of Sciences.
Italy's president Sergio Matarella and various non-government organisations were also due to take part in the summit. Its agenda also includes forced migration and human trafficking, a scourge exacerbated by desertification.
Francis will this summer publish his widely anticipated encyclical on the global environment and man's relationship to nature.
The Paris summit on climate change in December is widely seen as the last opportunity for a global deal to manage carbon emissions and set some limit to rising temperatures.
