Analysis of over 2.1 million deaths across Greece from 2000-2019 reveals heatwaves increase mortality risk by 8-15%, with the highest vulnerability among women and adults over 85. Using six different heatwave definitions and Bayesian modeling, researchers found human-induced climate change accounts for 51-94% of heat-related deaths, with this proportion rising over time. The study detected no evidence of population-level adaptation despite two decades of exposure. This research represents a significant advancement in climate attribution methodology applied to mortality data, moving beyond simple correlations to quantify the specific human fingerprint on heat deaths. The Mediterranean region faces escalating thermal stress as global temperatures rise, making Greece a bellwether for European heat vulnerability. However, the case-crossover design cannot establish long-term causal relationships, and the study relies on temperature modeling rather than direct measurements. As a preprint awaiting peer review, these findings require validation before informing policy. The results nonetheless underscore the urgent need for heat-health warning systems and targeted protection strategies, particularly as current adaptation measures appear inadequate against the mounting climate-driven mortality burden.