Voice of America: The United Nations is calling for urgent action to halt climate change on the 20th anniversary of the Intergovernmental Panel on Climate Change. The U.N. Secretary General and other eminent personalities were present at the official ceremony, which celebrated this event in Geneva from where Lisa Schlein reports for VOA For much of the past 20 years, studies by the Intergovernmental Panel on Climate Change have been greeted with skepticism and even vilified in some quarters. But, UN …