1. Rapidly reduce dependence on fossil fuels. We must do this to avert worse climate impacts, but also because the fuels themselves will be more scarce and expensive. Ending our reliance on coal, oil, and natural gas proactively with minimal social disruption will require a rapid redesign of transportation, agriculture, and power-generation systems.
2. Adapt to the end of economic growth. This means reworking, even reinventing, our existing economic system, which functions only in a condition of continuous expansion. Banking, finance, and the process of money creation will all need to be put on a new and different footing.
3. Design and provide a sustainable way of life for 7 billion people. We must stabilize and gradually reduce human population over time, using humane strategies such as providing higher levels of education for women in poor countries. But even in the best case, this objective will take decades to achieve; in the meantime, we must continue to support existing human populations while doing a better job of providing basic services for those at the bottom of the economic ladder. We must accomplish this in the context of a nongrowing economy and with a shrinking stream of resource inputs, and we must do it without further damaging the environment.
4. Deal with the environmental consequences of the past 100 years of fossil-fueled growth. Even if we cease all environmentally destructive practices tomorrow, we still face the momentum of processes already set in motion throughout decades of deforestation, overfishing, topsoil erosion, and fossil-fuel combustion. First and foremost of these processes is, of course, global climate change, which will almost certainly have serious impacts on world agriculture even if future carbon emissions decline sharply and soon.