The uneven distribution of incoming and outgoing radiation is the primary driver of the climate system. The resulting flows of energy by the climate components (atmosphere, ocean, ice, etc) determine the climate. Ultimately, the net difference between incoming and outgoing radiation determines if the climate is changing. Hence, estimating and understanding energy transports is essential for current climate assessment and future prospects.
A detailed outline of the process of estimating energy flows is described here. The focus on the mass budget is because the energy transports are meaningful only if the mass budget is closed.
National Center for Atmospheric Research Staff (Eds). Last modified 06 Sep 2013. "The Climate Data Guide: Budgets: Mass, Moisture, Energy." Retrieved from https://climatedataguide.ucar.edu/climate-data/budgets-mass-moisture-energy.