More than four decades of energy data reveal that global mitigation efforts to date are failing to rein in GHG emissions. This raises the issue of carbon lock-in (CO2 lock-in) in the electricity generation sector, where decisions are being made to extend the life of existing heavy-polluting infrastructure, or to engage in developments that fail to take account of new technologies and/or alternative energy sources. In this way, CO2 emissions being locked in for the expected lifetime of the stationary energy sector’s infrastructure, often well beyond recognised emissions reduction target periods. The consequences of inadequate global response to this looming problem are considerable, threatening the adequacy of GGEs’ mitigation and shifting substantially higher costs to the future. Existing policy and legislative responses of the EU and Australia are used to illustrate the divergent responses to this barrier to future decarbonisation of the energy sector.