U.N. Secretary-General Ban Ki-moon on Friday appointed former New York City Mayor Michael Bloomberg as his special envoy for cities and climate change, in a bid to build momentum ahead of a planned U.N. conference in September. Ban said Bloomberg will assist him in "consultations with mayors and related key stakeholders, in order to raise political will and mobilize action among cities as part of his long-term strategy to advance efforts on climate change." Ban is seeking to re-energize the global climate change debate and boost the United Nations' role. The new U.N. role for Bloomberg - a billionaire philanthropist who left office last month - was reported by Reuters on Thursday. Samantha Power, U.S. ambassador to the United Nations, was quick to welcome Bloomberg's appointment, posting on Twitter: "Mayor @MikeBloomberg knows how to get things done. We need more leaders like him here @UN." Bloomberg made combating climate change a key focus during his 12 years leading the United States' most populous city. He also advocated for national climate change legislation. He has played a leading role in the C40 Cities Climate Leadership Group, an international group of mayors created in 2005 and dedicated to reducing greenhouse gas emissions. The C40 group, of which Bloomberg is president of the board, is to meet in Johannesburg next week. Bloomberg announced last month that New York City's greenhouse gas emissions have dropped by 19 percent since 2005, putting the city nearly two-thirds of the way to meeting the goal he set five years ago. In the blueprint he launched in 2007, called PlaNYC 2030, Bloomberg set a goal to slash citywide emissions 30 percent by 2030 through a number of initiatives, such as requiring hybrid taxi cabs, building bike lanes and retrofitting municipal buildings to make them more energy efficient. The United Nations will host a one-day climate change summit in New York on Sept. 23, 2014. Many developing nations want that to be a deadline for rich countries to outline planned cuts in greenhouse gases beyond 2020 as a key step towards a global climate deal in 2015. Last month, Ban appointed former Ghana President John Kufuor and former Norwegian Prime Minister Jens Stoltenberg as special envoys on climate change to help drum up support for the September conference. http://english.ahram.org.eg/News/93152.aspx