Our food supply is massively contingent on natural geological goods and services. Farmers cultivate a geological substrate, the soil, and depend upon geological delivery systems such as the water and weathering cycles, to keep crops growing. They are constrained by natural processes of erosion and by the geochemical processes that redistribute and cycle the nutrient elements. Modern agribusiness has enabled us to overshoot the human carrying capacity of the planet by heavily mortgaging our future to the use of high inputs of non-renewable geological resources, particularly oil, gas and fertilizer raw materials. As a consequence, agriculture as practiced in the developed world is unsustainable over anything other than the short term. Since the Neolithic Revolution, some 10 to 13,000 years ago, we have become a potent geological agent in our own right, modifying landscapes and geological processes, and accentuating chemical, physical and biological changes in soils, waters and sediments. All of our activities result in the drawdown of the natural capital of the earth, with current rates from 1 to 2 orders of magnitude faster than the rates at which natural processes achieve comparable effects. In the USA the agricultural scar or footprint on the land now covers about 60% of the available soils as crop or range land. Worldwide we have essentially taken over the temperate grassland biome, as well as substantial areas of temperate forest and wetland. In effect, agriculture is strategically situated to consume the biosphere from within. In modifying the land by cultivation we compromise the ability of the soil to perform its natural ecological functions of providing habitat and collecting and redistributing energy and matter within the biosphere. Agricultural research has developed techniques for minimizing our impact, particularly where soil degradation and adverse effects on water resources are concerned, but a population that continues to grow and to increase per-capita consumption, makes increased impact inevitable. Sustainable agriculture on a scale large enough to provide food and fiber to support a world population expected to reach 9 billion people or more by 2050 remains an improbable dream. The fundamental problem is behavioral (though some might say cultural) rather than technical. As a species we have managed a temporary escape from the negative feedback of natural selection that keeps other species in check. We have accomplished this principally by two unrepeatable strokes of good fortune – the ‘discovery' just over 500 years ago, of a New World full of low entropy resources, and the exploitation of a rapidly diminishing stock of oil and gas. Consequently we have produced a human economy that recognizes none of the scientifically sanctioned default positions that define limits to material development. The ‘no limits' paradigm that dominates economic thought in the affluent nations at present, is and always has been a recipe for disaster. Our propensity to exhaust the resources we use may be learned or it may be hard-wired – a consequence of the basic Darwinian drive to eat, survive and reproduce. Regardless, we have developed a culture of extravagant consumption where one of equity and moderation is needed. A change in behavior is our only hope if human civilization is to last for much longer. Specifically, we need to learn to live within limits. The haves need to cut back on their resource consumption so that the have-nots may achieve a reasonable level of material comfort. Furthermore, we must base our economy on the renewable energy of contemporary, rather than fossil sunlight, and we must redesign our system of food production accordingly. However, even if we could accomplish all of these objectives, we would still need to decrease the human population on the planet (maybe to between 2 to 4 billion) in order to develop a sustainable society. All of this is a big ask, and may only come to pass if forced upon us.