Pretoria -The outcome of the United Nations climate change conference in Copenhagen, Denmark, will have reverberations for the future of humanity and the planet, says United Nations (UN) Secretary General Ban Ki-moon.
"We've come a long way in just two years' time, but what we do now over the next two weeks (in Copenhagen) will determine how we fare," Ban told reporters at UN headquarters in New York on Tuesday.
"Copenhagen can and must be a turning point in the world's efforts to prevent runaway climate change," he said.
United States President Barack Obama, President Jacob Zuma, Chinese Premier Wen Jiabao and other heads of state are set to join more than 15 000 participants taking part in the summit.
It is hoped that the nations will wrap up an agreement on an ambitious new climate change deal.
Ban said that never before had so many different nations of all size and economic status made so many pledges together.
Yvo de Boer, Executive Secretary of the UN Framework Convention on Climate Change (UNFCCC) said the start of the conference had been "very positive and encouraging," with clear calls made for urgent action on climate change.
However, he said a real difference will be made only if it impels significant and concrete action after the conference ends.