Hydraulic fracturing (“fracking” in the popular literature; “fracing” in some technical journals) is a technique for expanding gas and oil production. It is dramatically raising expectations for future gas and oil production, and technological optimists are hailing it as the answer to fears of a decline in world fossil energy production. In fact, it is still largely an unknown, and we cannot say with any confidence how it will affect the future of fossil energy. If indeed it does contribute substantially to world energy supplies – particularly gas – there will be profound ramifications, and they are not all benign. If it is simply used to support more growth, the new supply will support an unsupportable life style for a little longer and then lead to a deeper collapse. If we recognize the limits to growth, perhaps we can use it to ameliorate the transition. I shall describe the process briefly, identify some of its strengths and dangers, and offer a tentative evaluation of its potential impacts on world issues from climate change to food and the future of human populations.