This article assesses the feasibility of a 50% reduction in CO2emissions by 2050 using a large-scale Post Keynesian simulation model of the global energyenvironmenteconomy system. The main policy to achieve the target is a carbon price rising to $100/tCO2by 2050, attained through auctioned CO2permits for the energy sector, and carbon taxes for the rest of the economy. This policyinducestechnological change. However, this price is insufficient, and global CO2would be only about 15% below 2000 levels by 2050. In order to achieve the target, additional policies have been modelled in a portfolio, with the auction and tax revenues partly recycled to support investment in low-GHG technologies in energy, manufacturing and transportation, and no-regrets options for buildings.This direct support supplements the effects of the increases in carbon prices, so that theacceleratedadoption of new technologies leads to lower unit costs. In addition the $100/tCO2price is reached earlier, by 2030, strengthening the price signal. In a low-carbon society, as modelled, GDP is slightly above the baseline as a consequence of more rapid development induced by more investment and increased technological change.