Members of environmental groups hold up banners calling for renewable energy at the United Nations climate talks that took place in Bonn, Germany, in 2015. Bonn was the site of the last United Nations Climate Change Conference in November 2017, in which countries attempted to hammer out the specifics of the Paris Agreement of 2015. Many of the issues went unresolved in Bonn, leaving plenty of questions heading into the next conference in Poland in December.