At the upcoming Rio+20 summit in Brazil, more than 135 heads of state and government, and up to 50,000 participants, including business executives and civil-society representatives, will come together to express their collective commitment to advance inclusive, sustainable development.

But, despite the goal of unity and collective action underpinning the summit, the best way forward for the global economy is to build on the actions that individual countries and regions are taking in pursuit of their own interests.

Despite the summit's aspirational rhetoric, there is no consensus about how to achieve sustainable development. Advocates argue that "clean tech," "smart financing," and "investment-grade" public policies will usher in a new and enlightened era of economic growth that does not degrade the environment.

For opponents, however, green growth is more like "green-washed growth" - a merely cosmetic change to the business-as-usual approach that gave us the global financial crisis, and that perpetuates poverty and exacerbates inequality.

Given this divergence, policymakers must grasp today's immediate opportunities, rather than rely on the desirable - but remote - possibility of global consensus. Counting on today's resource-intensive, profit-driven world economy to deliver quickly the global public goods of environmental security and development requires profound optimism, especially given the dire political and economic circumstances of key powers, notably Europe and the United States.

Capital markets' shortsightedness - on plain display in recent years - does little to raise hopes. Although investment in clean technology is on the rise, it is far from reaching the more than US$1 trillion annually needed to deliver green energy and infrastructure fit for the 21st century.

Global economy in disarray

Robust policy interventions are needed, but global policy platforms are in disarray. Yet today's global economy is all we have, so we need to make the most of it in driving forward the green changes that are needed. That means taking advantage of unilateral action by individual countries or regional groupings to put the global economy on a more sustainable path.

Some useful policies are already in play: China's massive public subsidies are powering up a cadre of internationally minded clean-tech companies; Europe is attempting to extend its carbon-trading scheme to non-European airlines; and the US is moving towards energy security through domestic shale-gas exploitation.

Rather than seeking to contain this unilateralism, world leaders should leverage it in pursuit of global public goods. Such a strategy's success depends on three factors: a focus on a small number of big-ticket national and regional actions, adequate policy leverage over these actions, and international coalitions to steer them along a legitimate path.

One area to target is sovereign wealth funds, whose combined assets are set to grow over the next decade from US$3-4 trillion to US$10 trillion.

Furthermore, governments procure roughly US$3-4 trillion of goods and services annually, a huge potential force for inducing market transformations.

And fossil-fuel subsidies exceed US$400 billion annually, while the yearly total for public subsidies of natural resources is estimated to exceed US$1 trillion. China alone will increase its level of outward direct investment over the next decade by an estimated US$1 trillion - a gift to sustainability if its deployment can be shaped with such a vision in mind.

Shaping unilateralism requires new ways to collaborate, and such platforms are emerging. The US-sponsored Clean Energy Ministerial, the Abu Dhabi-based renewable-energy agency, IRENA, and the Korean-initiated Global Green Growth Institute can provide pragmatic pathways for enhancing unilateral actions.

In its current state, the global economy is unfit to serve today's collective needs, let alone tomorrow's.

Capital markets must be reformed, not only to ensure that they are resilient - the focus of financial-market reform nowadays - but also to guarantee that money is allocated in ways that secure the resilience of the real economy and the natural environment on which we depend.

The most powerful force in today's global political economy are unilateral decisions taken by countries and regional groups in pursuit of their own economic interests. Those attending the Rio+20 Summit should embrace this promising, if awkward, strategic opportunity.

Simon Zadek is senior fellow at the Global Green Growth Institute and associate senior adviser at the International Institute of Sustainable Development. Copyright: Project Syndicate, 2012.www.project-syndicate.org. Shanghai Daily condensed the article.