Despite widespread disappointment among skeptics about the outcome of the recent Rio+20 UN Conference on Sustainable Development in Rio de Janeiro, China considers the event a step forward. That's not because China is less ambitious, but because it knows well progress can be made only incrementally.

Twenty years after the original Earth Summit in the same city put sustainable development on the global agenda, Rio+20 produced a final document titled "The Future We Want." In the document, countries promised to establish a high-level political forum to follow up on international commitments. They also promised to start negotiations on "sustainable development goals," new targets that will take effect after the UN Millennium Development Goals are due to be accomplished by 2015.

On top of these pledges, countries reaffirmed their adherence to the fundamental principle of "common but differentiated responsibilities." Although this commitment is not new, it is of pivotal importance. While sustainable development is a shared pursuit, it is unrealistic to demand all countries assume identical responsibilities and meet uniform standards given their vastly different national conditions.

Developed countries, with their financial and technological prowess, are expected to take the lead. They should not only embrace sustainable ways of life and production, but also help developing countries through technology transfers and financial assistance. Industrialized nations are duty-bound because they have consumed plenty of the world's resources since the Industrial Revolution began 250 years ago.

Likewise, developing countries should also commit themselves to economic, social and environmental sustainability as they pursue further development. "Green economy" provides a new option for countries to usher in a sustainable future. But it should not be used as a pretext to deprive poor countries of opportunities to boost economic growth and improve people's livelihoods.

All these agreements are praiseworthy and will have far reaching implications for the world's sustainable development drive. In addition, Rio+20 was successful also because it raised public awareness of the urgency of sustainable development. More than 50,000 representatives from all sectors of society participated in a wide range of events designed to forge consensus and imbue the public with a strong sense of sustainability. Governments, NGOs, companies and universities made nearly 700 voluntary commitments, a testament to the great enthusiasm people around the world show for this honorable cause.

Indeed, sustainable development calls for global efforts. The UN, which spearheads these efforts, faces an uphill battle to coordinate nations at different levels of development and interest groups with various agendas. But as long as political will persists, the world will stand a chance. At a time when daunting challenges remain in economic recovery, poverty reduction and environmental protection, we need reflections and constructive criticisms, but, more importantly, patience and results-oriented action. After all, Rome was not built in a day, and neither will be the edifice of sustainability. In this sense, Rio+20 was just one of the building blocks for this magnificent structure.