The Heartland Institute

From their website:

The Nongovernmental International Panel on Climate Change (NIPCC) is an international panel of nongovernment scientists and scholars who have come together to present a comprehensive, authoritative, and realistic assessment of the science and economics of global warming. Because it is not a government agency, and because its members are not predisposed to believe climate change is caused by human greenhouse gas emissions, NIPCC is able to offer an independent “second opinion” of the evidence reviewed – or not reviewed – by the Intergovernmental Panel on Climate Change (IPCC) on the issue of global warming.