UN, September 22 (RIA Novosti) - Humanity has less than 10 years to prevent irreversible climate change, and joint action is required to limit harmful emissions, the UN secretary general said Tuesday.

The highest-level conference on climate change opened on Tuesday at the United Nations to discuss how to combat global warming. Heads of state or government from more than 100 UN members arrived to attend the event.

The discussions will give an indication of what might be agreed at a December meeting in Copenhagen to negotiate a replacement for the Kyoto Protocol on climate change, some elements of which expire in 2012.

"Greenhouse gas emissions continue to rise. We will soon reach critical thresholds, consequences that we cannot reverse. The world's leading scientists warn that we have less than ten years to avoid the worst-case scenarios projected by the Intergovernmental Panel on Climate Change [IPCC]," Ban Ki-moon said.

"Indeed those worst-case scenarios are becoming ever more likely. We must halt the rise in global emissions," he said in his opening remarks to the United Nations Climate Change Summit Plenary.

Ban also called on the leaders of the world's leading industrial nations to be the first to concede regarding emissions.

"Instead of demanding concessions from others, let us ask how we can contribute to the greater good. A successful deal in Copenhagen will mean more prosperity, more security, more equity. It will expand the pie for all," he said.

"We need to build trust step by step. Today, I call on all the leaders of the industrialized countries in this room to take the first steps forward. If you do so, others will take bold measures of their own," he said.

Ban also urged leaders of developing countries to "accelerate their efforts. All countries must do more - now," he said.

The overwhelming consensus of climate change experts, environmental groups and organizations is that the climate change is caused by greenhouse gas emissions due to human activity, which is causing significant damage to the Earth, although a minority argues that the possible impact has not yet been proven.

Speaking at the UN summit, U.S. President Barack Obama said: "That so many of us are here today is a recognition that the threat from climate change is serious, it is urgent, and it is growing. Our generation's response to this challenge will be judged by history, for if we fail to meet it - boldly, swiftly, and together - we risk consigning future generations to an irreversible catastrophe."

"The security and stability of each nation and all peoples - our prosperity, our health, our safety - are in jeopardy. And the time we have to reverse this tide is running out. And yet, we can reverse it," he said.