Singer set up the Nongovernmental International Panel on Climate Change (NIPCC) in 2004 after the 2003 United Nations Climate Change Conference in Milan. NIPCC organized an international climate workshop in Vienna in April 2007, to provide what they called an independent examination of the evidence for climate change. Singer prepared an NIPCC report called "Nature, Not Human Activity, Rules the Climate," published in March 2008 by the Heartland Institute, a conservative think tank. ABC News said the same month that unnamed climate scientists from NASA, Stanford, and Princeton who spoke to ABC about the report dismissed it as "fabricated nonsense". In a letter of complaint to ABC News, Singer said their piece used "prejudicial language, distorted facts, libelous insinuations, and anonymous smears".