From the beginning of the climate change debate, advocates claiming that activities such as heating homes, operating factories and driving cars are causing global warming based their claim on an asserted scientific consensus. The foundation for their claim was the Intergovernmental Panel on Climate Change (IPCC) process, which involves scientists from around the world and the conclusion of its leadership that human activities were the cause of global warming and would cause serious future climate change unless action was taken to reduce greenhouse gas emissions. These conclusions were found in the Summary for Policy Makers, which is a political document which has been criticized for downplaying scientific uncertainties.
In fact, while the IPCC process does involve many leading scientists, it is a stretch to claim that they all agree with the conclusions about human impacts or represent a scientific consensus. The IPCC is controlled by a group of scientists appointed by their governments and the larger group of participating scientists are only involved in the chapters to which they are contributing authors. And, that does not include a role in approving or endorsing the Summary for Policy Makers which is the document that is most widely read and referenced by the media