The EU ETS was the first international climate policy instrument that directly targeted the CO2 emissions from major oil companies in Europe. The oil industry, which makes a living from some of the key sources of anthropogenic climate change, stands out as an important sector for achieving a low-carbon economy in Europe and other parts of the world. To what extent, how and under what conditions has the ETS affected the climate strategies of major multinational oil companies? Oil companies can be affected in the short term by holding emissions allowances, particularly in the refining sector, and more strategically in the longer term by carbon pricing and the possibility of diffusion beyond Europe.1