"For most people in the developing countries and Africa, climate change is a matter of life and death," said the South African leader as he formally opened a two-week conference with participants from 191 countries and the European Union.

The conference is seeking ways to curb ever-rising emissions of climate-changing pollution, which scientists said last week have reached record levels of concentration in the atmosphere.

Seasoned nongovernment observers said the outcome of the conference, which ends Dec. 9, is among the most unpredictable since the annual all-nation meetings began following the conclusion in 1992 of the basic treaty on climate change. "Everything seems to be fluid. Everything is in play," said Tasneem Essop, of WWF International.

The main point of contention is whether industrial countries will extend their commitments to further reduce carbon emissions after their current commitments expire next year. Most wealthy countries have said their agreement is conditional on developing countries like China, India and Brazil accepting that they, too, must accept legally binding restrictions on their own emissions.

Zuma said Sudan's drought is partly responsible for tribal wars there, and that drought and famine have driven people from their homes in Somalia. Floods along the South African coast have cost people their homes and jobs, he said.

"Change and solutions are always possible. In these talks, states, parties, will need to look beyond their national interests to find a solution for the common good and human benefit," he said.

The UN's top climate official, Christiana Figueres, said future commitments by industrial countries to slash greenhouse gas emissions is "the defining issue of this conference." But she said that is linked to pledges that developing countries must make to join the fight against climate change.

She quoted anti-apartheid legend and former President Nelson Mandela: "It always seems impossible until it is done."