This presentation introduces an Earth Model, CCEM (Coupling Coarse Earth Models), which is a simulation model representing the earth as a complex system and focusing on feedback loops associated with global warming. CCEM combines five simpler models, addressing energy availability, economic adjustment to energy scarcity, energy transition, global economy and CO2 emissions, and the impact of CO2 emissions on warming and society. The model aims to make implicit beliefs explicit and demonstrate that the same mental model can support various viewpoints by changing beliefs associated with "known unknowns." Five "known unknowns" discussed in the text include the future availability and cost of energy, energy needs and affordability for the economy, the speed of energy substitution, expected GDP growth, and the economic and societal consequences of global warming. These "known unknowns" have no consensus answers but making them explicit in models can help clarify differences in conclusions based on varying assumptions.