With just weeks to go before the Rio+20 Earth Summit, many are speculating about how many world leaders will show up and what kind of agreements they might reach on the key agenda items: creating a “green economy” and establishing an “international framework for sustainable development.” It is no coincidence that these two items appear side by side.

The term “green economy” was coined years ago – even prior to the first Earth Summit in 1992 – to provide a new lens through which to examine the links between economics and sustainability.

But it has gained a new impetus in a world where climate change is already a reality, commodity prices are rising, and basic resources such as clean air, arable land, and fresh water are increasingly scarce. A growing body of science, including the United Nations Environment Program’s upcoming Global Environment Outlook-5, is confirming what was glimpsed at Rio 20 years ago.

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Those who have invested in an economic model and production processes based on nineteenth- and twentieth-century models are perhaps understandably nervous about a paradigm shift. But so are some segments of civil society, which are concerned that a transition to a green economy might negatively affect the poor and expose them to greater risks and vulnerabilities.

Others question the efficacy of market-based approaches to drive sustainability, because markets can never deliver optimal social and environmental outcomes. Only strong institutions, including regulations and laws, can accomplish this.

We couldn’t agree more. The systemic crises in food, fuel, and finance that came to a head in 2008 – and that are ongoing in many countries – have their roots in an economic paradigm that has not accounted for the value of nature and its array of life-supporting services. As the recently released report “Towards a Green Economy: Pathways to Sustainable Development and Poverty Eradication” shows, the market economy as currently constituted has resulted in the misallocation of capital on an unprecedented scale.

Indeed, the deep and pervasive market failures – in carbon emissions, biodiversity, and ecosystem services – are accelerating environmental risks and ecological scarcities, and undermining human well-being and social equity. That is why the link to governance and institutions at Rio+20 is just as important as the transition to a green economy: markets are human constructs that require rules and institutions to guide not only their direction, but also their boundaries.

One concern among critics is that a transition to a green economy will essentially monetize nature, exposing the world’s forests, fresh water, and fisheries to the profit-seeking behavior of bankers and traders, whose shortcomings helped to trigger the financial and economic turmoil of the past four years. But is the question one of monetizing nature, or of valuing nature?

The fact is that nature is already being bought and sold, mined and marketed at knock-down prices that fail to capture its real worth, especially to the livelihoods of the poor. In large part, this reflects unregulated or missing markets that fail to capture the values that nature provides to us every day – point emphasized in the G-8+5 project on the Economics of Ecosystems and Biodiversity, hosted by the UNEP.

In a very real sense, the future of the planet is at stake in Rio. Without a real and lasting solution that recalibrates our current economic thinking at a systemic level, the scale and pace of change could soon push the planet past critical thresholds and make sustainable development everywhere an impossible dream. Although multilateralism is a slow and often painful process of cultivating consensus, some issues are so large that they transcend any one country.

Why, for example, does the world pursue a paradigm of economic growth that rests upon eroding the very basis of earth’s life-support systems? Can wealth be redefined and reframed to include access to basic goods and services, including those provided by nature free of cost, such as clean air, a stable climate, and fresh water? Is it not time to give human development, environmental sustainability, and social equity an equal footing with GDP growth?

All around us, warning lights are flashing yellow, if not red. But we know that new technology and innovation are driving changes in the way that energy is produced, how new markets for food and clean water are emerging, and how basic ecological services are now becoming scarce and valued.

Rio+20 is a moment for sharing knowledge and experience concerning successful transitions to greener and more resource-efficient economies. It is an opportunity to begin developing the capacity at all levels to transform our economies into engines of growth and jobs that do not deplete our resources or create new liabilities that will be a drag on growth and human health for years to come.

The challenge ahead will be to reconcile the emerging economic reality with the social values and ethics needed to produce a balanced and inclusive green economy. That, in the words of UN Secretary-General Ban Ki-moon, is a “future that we all want.” It is a future that could unfold with defining and decisive leadership by world leaders at Rio+20.