Former UN Secretary General Kofi Annan says he supports Pope Francis' calls for swift action to protect the Earth and fight global warming.
Mr Annan said that climate change "could displace tens of millions of people, dwarfing current migration and fuelling further conflicts".
In November, international leaders will gather in Paris to try to seal a deal to reduce carbon emissions.
Mr Annan is Chair of the Africa Progress Panel, which is campaigning for international commitment to reduce the impact of global climate change on Africa.
