TOPSHOTS A carpenter works on cleaning a crucifix in the capitol main Cathedral Notre Dame during preparation and rehearsal for the Pope visit on November 25, 2015 in Bangui, Central African Republic. Pope Francis said the world was facing a "grave environmental crisis" as he arrived in Kenya on Wednesday on a landmark Africa trip just days before a crucial UN summit aimed at curbing climate change. He also warned of the need to tackle poverty as a key driver of conflict and violence as he kicked off a landmark Africa trip fraught with security concerns and urged Kenya's leaders to work with "transparency" to ensure a fair distribution of national resources as criticism grows over runaway graft in this east African country. Pope Francis will visit Central African Republic on the 29 and 30 November. AFP PHOTO / GIANLUIGI GUERCIA