Who is part of the IPCC?(and a definition)
Let's start from the beginning: the definition. The IPCC is an "Intergovernmental Panel on Climate Change".
The IPCC was established in 1988. At the time, evidence of climate change had already been mounting for a long time. Scientists wrote numerous studies in the 1970s attesting to this. The idea emerged to provide the world with a working group, an international body responsible for taking an interest in this phenomenon and documenting it to make these findings more widely known.
Two major organisations took charge of this:the United Nations Environment Programme (UNEP) and the World Meteorological Organisation (WMO). Together, they created the Intergovernmental Panel on Climate Change (IPCC).