Transport is responsible for 30% of greenhouse gas emissions in France, and this figure is constantly increasing. Technological innovations and the push for a “modal shift” aren’t enough to compensate for the increasing number of oil-fuelled kilometers travelled. Pesonal carbon allowances are presented as an alternative to taxation. These would allow us to acknowledge and respect the planet’s limits, distribute energy resources equitably and pursue public policies that respond to this new environmental state of affairs. Such allowances applied to polluting travel could take the form of a carbon card and be distributed according to democratically defined criteria. Would such a proposal be possible, fair and desirable?