Climate change information is increasingly available and robust at regional scale for impacts and risk assessment. Climate services and vulnerability, impacts and adaptation studies require regional scale multi-decadal climate observations and projections. Since the IPCC Fifth Assessment Report (AR5), the increased availability of coordinated ensemble regional climate model projections and improvements in the level of sophistication and resolution of global and regional climate models, completed by attribution and sectoral vulnerability studies, have enabled the investigation of past and future evolution of a range of climatic quantities that are relevant to socio-economic sectors and natural systems. Chapter 12 consolidates core physical knowledge from preceding AR6 Working Group I (WGI) chapters and post-AR5 climate impact assessment literature to assess the spatio-temporal evolution of the climatic conditions that may lead to regional scale impacts and risks (following the sectoral classes adopted by AR6 WGII) in the world’s regions (presented in Chapter 1). {12.1}