Associated Press: The next U.S. president must show greater leadership than previous administrations in tackling climate change, the head of the United Nations said Sunday. “All the countries in the international community are looking for more and greater leadership from the United States,” U.N. Secretary-General Ban Ki-moon said after a celebration to mark the 20th anniversary of the founding of the Intergovernmental Panel on Climate Change. Ban praised the administration of U.S. President …