A neutral body of the United Nations who provides the most influential assessments on climate change. The IPCC elaborates different kinds of reports: a) The Assessment reports in which the state of scientific, technical and socio-economic knowledge on climate change is presented and the implications, the risks, the adaptation and mitigation options are discussed. b) The Special reports which deal with topics agreed by its member governments. c) The Methodology reports with guidelines for the elaboration of greenhouse gasses inventories. Three working groups are involved in the elaboration of reports: the first addresses the Physical Science Basis, the second deals with Impacts, Adaptation and Vulnerability and the last focuses on Mitigations. The IPCC reports are policy-relevant but not policy-prescriptive, they are expected to inform the decisions and international negotiations of policy makers.