UN chief Ban Ki-moon has pressed world leaders attending next week's UN climate summit to publicly commit to reaching a global climate change deal in Copenhagen in December. Addressing a news confernce ahead of UN General Assembly session he said no issue better demonstrates the need for global solidarity. <br/>Ban said the current slow pace of the climate change negotiations is a matter of deep concern. Ban also said that world leaders should publicly commit to sealing a deal in Copenhagen. <br/>Europe and the US administration continue to have differences over how to cut emissions and tackle global warming.