Pope laments 'meaningless lives' in tying human trafficking to climate change

Pontiff follows encyclical on fossil fuels with environmental summit of mayors and links climate change to migration, slavery and 'uncurtailed growth of cities'

Pope Francis said he had "great hopes" that a fundamental agreement to tackle climate change would be reached in Paris later this year and he believed the United Nations needed to play a central role in the fight against global warming.

"The UN really needs to take a very strong position on this issue, particularly the trafficking of human beings " [a problem] that has been created by climate change," the pope said.