Groundwater depletion is a critical issue with significant impacts on water availability in diverse climatic settings. This study uses a range of statistical methods and remote-sensing techniques to investigate the factors, specifically, climatic, hydrological, and human-driven changes, that influence groundwater levels (GWLs) in aquifers in a temperate region (three aquifers in southwestern Canada) and a semi-arid region (four aquifers in southern Iran). Change point and trend analyses reveal significant declines in GWL (groundwater depletion) in one aquifer in the temperate region and in all aquifers in the semi-arid region, despite climate variables such as precipitation, temperature, and potential evapotranspiration showing minimal changes over the study period. In contrast, human-induced factors, including agricultural expansion, deforestation, and increases in the number of pumping wells, have occurred in the aquifers of both regions. The comparative design highlights contrasting resilience: Canadian aquifers exhibit partial recovery under management interventions, whereas Iranian aquifers demonstrate persistent over-extraction with limited recharge. These findings emphasize that human pressure, rather than climate, is the primary driver of depletion and that adaptive, region-specific groundwater governance is critical for sustainable management under future climate and land-use change.