Introduction: Cardiac electrophysiology and intracellular calcium (Ca²⁺) handling exhibit significant inter-cellular variability, influencing action poten-tial dynamics, arrhythmia susceptibility, and drug response. Population mod-elling approaches have successfully captured this variability through random parameter sampling and output filtering. However, extending such models to tissue scale remains challenging, as multiple parameters must vary spatially while preserving physiological correlations. Here, we develop a calcium-driven framework to generate heterogeneous populations of human atrial cell models based on coordinated ionic conductance remodelling. Methods: A two-dimensional atrial tissue model was simulated with cell-specific intracellular calcium targets. The tissue was paced to steady state and the parameters describing the conductance (expression) of each ion channel were then iteratively modified until the average cytosolic calcium concentration in the cell was within a set precision of the calcium target. The resulting steady-state data was then used to fit a linear relationship between calcium and L-type calcium current scaling factor (ICaL scale). Spatially heterogeneous calcium target maps were generated, and ICaL_scale was assigned directly from this fitted relationship. Scaling of other ionic currents and calcium-handling fluxes was defined proportionally using fixed weights. Independent heterogeneity in Transient outward potassium current was in-troduced using a truncated random distribution. Results: A linear Ca²⁺–ICaL relationship was obtained using both single cell and tissue model derivations. The tissue-derived populations exhibited broader variability ion current conductances, manifesting substantial action potential and Ca²⁺ transient variability in uncoupled, isolated cells. Distinct action potential morphologies were produced including notch–dome separa-tion and region-dependent repolarisation dynamics. Conclusions: Calcium-targeted feedback generates heterogeneous cell and tissue populations using a single parameter (Ca_target), enabling simple and reproducible tissue modelling.