Green growth, the promotion of energy efficiency and clean energy technologies and sustainable development are frequently viewed as complementary goals by international policymakers. This paper argues that green growth will not ensure sustainable economic development as long as global ecosystem degradation and loss means that the world continues to face worsening problems of ecological scarcity — the loss of myriad benefits, or “services”, as these systems are exploited for human use and activity. Overcoming this problem requires addressing further sustainability and funding challenges. The sustainability challenge is to overcome a vast array of market, policy and institutional failures that prevents recognition of the economic significance of this scarcity. The funding challenge is to bridge the shortfall between the global benefits that humankind receives from ecosystems and what we are willing to pay to maintain and conserve them. Improving economic and scientific analysis of ecological scarcity, valuing the loss in benefits, and translating the implications into policy are the key steps for addressing the sustainability challenge. Exploring and implementing a range of innovative financing mechanisms, from international payments for ecosystem services to financial and currency transactions taxes to international financing facilities are possibilities for alleviating the funding challenge.