This thesis examines the impact of European refinery reforms on emissions reduction and economic sustainability, using the Global Change Assessment Model (GCAM) to simulate four scenarios for the EU-15: a Reference Scenario (REF), an Increased Carbon Tax pathway (ICT), a Biofuel Subsidy pathway (BIO), and a Net Zero pathway (NZR). The results show divergent trajectories. REF maintains rising refinery emissions and fossil dependence, reflecting the risks of inaction. ICT delivers moderate reductions through efficiency and process optimization, while BIO supports diversification and partial substitution of conventional fuels. However, both remain insufficient to achieve long-term climate stabilization. Only NZR enables systemic transformation, with emissions declining to net zero by 2050, rapid deployment of carbon capture and storage (CCS), expansion of bioenergy, and stabilization of CO₂ concentrations and radiative forcing within climate targets. These findings underscore that incremental reforms mitigate risks but cannot deliver climate neutrality. Only comprehensive, ambitious strategies can align European refineries with long-term environmental goals while sustaining industrial competitiveness. Keywords: refinery,