Recent climate studies have shown that average global temperature rises are almost linearly related to the cumulative emissions of greenhouse gases emitted over a given timeframe. This has resulted in the concept of the remaining global ‘carbon budget’ that provides a better-than-evens chance of avoiding more than a 2oC temperature rise. In particular, the Intergovernmental Panel on Climate Change recently suggested that CO2 emissions between 2011 and 2050 cannot exceed around 1,100 Gt CO2 if the 2oC limit is not to be exceeded. It has subsequently been noted by many authors that the CO2 emissions embodied within current estimates of fossil fuels reserves are more than three times this carbon budget. The policy implications of this for fossil fuel companies, those who invest in them, and politicians are profound. For example, politicians need to realise that their instinct to exploit their territorial fossil fuel resources as quickly and completely as possible is inconsistent with their stated commitment to the 2oC temperature limit. In respect of the companies, in a world of stringent carbon control their substantial exploration budgets appear to be largely self-defeating in aggregate.    ​