The high-profile event comes 20 years after Rio's First Earth Summit when nations vowed to roll back climate change, desertification and species loss. The summit was launched to a three-minute movie, "Welcome to the Anthropocene" that gave a visual trip through the dramatic changes in the environment since the Industrial Revolution.
The Anthropocene is the name given by many scientists for a new era in Earth's history. It derives from Greek words to indicate the era of humans. Brittany Trilford, a 17-year-old student from New Zealand and winner of the "Date with History" youth video speech contest, then addressed the leaders, challenging them to lay the foundation for a more sustainable world.
Some 191 speakers are expected to take the floor until Friday when the summit leaders are to give their seal of approval to a 53-page draft document agreed by negotiators Tuesday. The draft called "The Future We Want" outlines measures for tackling the planet's many environmental ills and lifting billions out of poverty through policies that nurture rather than squander natural resources.
One of the biggest areas of dispute was on "Sustainable Development Goals," or SDGs, that will replace the UN's Millennium Development Goals after these objectives expire in 2015 and on promoting the green economy. As the summit got under way, eight multilateral development banks announced that they would set aside $175 billion to finance sustainable transport systems over the next decade.
The pledge was made jointly by the World Bank, Asian Development Bank, African Development Bank, Inter-American Development Bank, CAF-Development Bank of Latin America, European Bank for Reconstruction and Development, European Investment Bank and Islamic Development Bank. Transport is one of the fastest-growing source of greenhouse gases, driven especially by urban growth in giant emerging economies. Around a billion people are likely to move to cities over the next 20 years, which means traffic congestion, air pollution and road accidents will become major urban challenges.