This article considers the role of activism and politics to restrict the supply of fossil fuels as a key means to prevent further climate injustices. We firstly explore the historical production of climate injustice through extractive economies of colonial control, the accumulation of climate debts, and ongoing patterns of uneven exchange. We develop an account which highlights the relationship between the production, exchange, and consumption of fossil fuels and historical and contemporary inequalities around race, class, and gender which need to be addressed if a meaningful account of climate justice is to take root. We then explore the role of resistance to the expansion of fossil-fuel frontiers and campaigns to leave fossil fuels in the ground with which we are involved. We reflect on their potential role in enabling the power shifts necessary to rebalance energy economies and disrupt incumbent actors as a prerequisite to the achievement of climate justice.