The Scenario Model Intercomparison Project (ScenarioMIP) is a key component of the Coupled Model Intercomparison Project Phase 6 (CMIP6), focusing on providing multi-model climate projections based on alternative scenarios of future emissions and land use changes. The project aims to facilitate integrated research across multiple scientific communities, including climate science, integrated assessment modeling, and impacts, adaptation, and vulnerability studies. ScenarioMIP will address specific scientific questions related to the climate effects of particular forcing aspects, such as land use and aerosols, and the consequences of scenarios that limit warming to below 2°C. The experimental design includes eight alternative 21st-century scenarios, one large initial condition ensemble, and long-term extensions, divided into two tiers based on priority. The scenarios are based on Shared Socioeconomic Pathways (SSPs) and will be driven by emissions and land use scenarios generated with integrated assessment models (IAMs). The project will provide a basis for investigating targeted science and policy questions, such as the role of specific forcings, the effect of a peak and decline in forcing, and the relative contributions of uncertainty from scenarios, climate models, and internal variability.The Scenario Model Intercomparison Project (ScenarioMIP) is a key component of the Coupled Model Intercomparison Project Phase 6 (CMIP6), focusing on providing multi-model climate projections based on alternative scenarios of future emissions and land use changes. The project aims to facilitate integrated research across multiple scientific communities, including climate science, integrated assessment modeling, and impacts, adaptation, and vulnerability studies. ScenarioMIP will address specific scientific questions related to the climate effects of particular forcing aspects, such as land use and aerosols, and the consequences of scenarios that limit warming to below 2°C. The experimental design includes eight alternative 21st-century scenarios, one large initial condition ensemble, and long-term extensions, divided into two tiers based on priority. The scenarios are based on Shared Socioeconomic Pathways (SSPs) and will be driven by emissions and land use scenarios generated with integrated assessment models (IAMs). The project will provide a basis for investigating targeted science and policy questions, such as the role of specific forcings, the effect of a peak and decline in forcing, and the relative contributions of uncertainty from scenarios, climate models, and internal variability.