The scenario used as starting or reference point for a comparison between two or more scenarios. [Note 1: In many types of climate change research, reference scenarios reflect specific assumptions about patterns of socio-economic development and may represent futures that assume no climate policies or specified climate policies, for example those in place or planned at the time a study is carried out. Reference scenarios may also represent futures with limited or no climate impacts or adaptation, to serve as a point of comparison for futures with impacts and adaptation. These are also referred to as baseline scenarios in the literature.
IPCC
Climate Change 2022: Impacts, Adaptation and Vulnerability
IPCC Report