Poleward moisture transport into the Arctic occurs via short-lived, episodic intrusions of warm, moist air masses. These extreme transport events are associated with an enhanced greenhouse effect that is expected to slow sea-ice growth in winter and hasten the start of spring melt season. Yet, their impact on the Arctic energy balance averaged over longer time scales has been difficult to quantify, in part due to the challenge in separating local and remote Arctic moisture sources. Here we implement numerical water tracers in version 2 of the Energy Exascale Earth System Model (E3SMv2) to quantify how moisture is drawn from source regions outside the polar cap and injected over the polar cap. A moist intrusion tracking algorithm, developed specifically for the Arctic and based on global atmospheric river tracking algorithms, is further used to identify extreme events. For a series of E3SMv2 simulations spanning pre-industrial through future emissions scenarios, the detailed provenance of Arctic water vapor, both vertically resolved and in intrusion events, will be presented. By revealing the sources and transport mechanisms of Arctic moisture in a changing climate, this research paves the way for understanding how moisture transport sustains water vapor and cloud feedbacks over the Arctic, and thereby elicits sea ice retreat and its attendant feedbacks.