The United Nations Conference on Sustainable Development to be held in Rio de Janeiro, Brazil, next year will be an opportunity for humanity to strengthen its commitment to making the transition to a "green economy" to help lift people out of poverty, a senior UN official said Tuesday.

"We cannot wait for another 20 years," Sha Zukang, the Under-Secretary-General for Economic and Social Affairs, told reporters at UN Headquarters, where a two-day preparatory meeting was due to end later today.

"The time to commit is at Rio 2012," added Mr. Sha, who is also the Secretary-General of the Conference, which has been dubbed 'Rio 2012.'

He said that UN Members States have, through a General Assembly resolution, identified three objectives for the Conference – to renew commitment to sustainable development; to identify progress and gaps; and to identify new and emerging challenges.

The Conference's two themes are green economy in the context of sustainable development and poverty eradication, and institutional framework of sustainable development.

Mr. Sha said he hoped Member States will be able to agree on "green economy as a pathway to sustainable development" and come up with a "tool kit" for the implementation of the principles that they will agree on.

Last week, Mr. Sha cautioned that the failure to tackle poverty can only lead to rising social tensions, ecological pressures and economic crisis, stressing the importance of a transition to a green economy that fosters sustainable development and poverty eradication.

Rio 2012 will take place 20 years after the UN Conference on Environment and Development, also known as the "Earth Summit," that was held in Rio de Janeiro, where countries adopted Agenda 21 – a blueprint for rethinking economic growth, better protecting and managing ecosystems and creating a safer, more prosperous future for all.