These areas can be turned into poles of clean and sustainable growth, linking cost savings with employment creation, income-generation and investment opportunities. In so doing, in addition to relaunching growth (that was brought to a halt by the economic crisis), these areas can address key issues involved in the energy, climate, food and water crises, and make substantial contributions towards meeting the Millennium Development Goals (MDGs). Flowever, the significance and difficulty of the choices that policymakers face cannot be exaggerated.