The United Nations convened on Tuesday the Summit on Climate Change, with the largest-ever gathering of world leaders at UN Headquarters in New York to discuss possible actions to tackle the global challenge.
Nearly 100 heads of state and government were at the summit, the aim of which is to mobilize the political will and generate the momentum needed to reach an ambitious agreement at the UN Climate Conference in Copenhagen in December.
The agreement is set to go into effect in 2012, when the first commitment period of the Kyoto Protocol expires.
In remarks to the opening session held at the UN General Assembly Hall, UN Secretary-General Ban Ki-moon urged world leaders to provide the support and guidance for climate negotiations which are proceeding at "glacial speed."
"Your negotiators need your direct political support and guidance to resolve core issues ... to accelerate the pace of negotiations ... and to strengthen the ambition of what is on offer," Ban said.
The climate summit aims to advance the negotiations, but is not a negotiating session itself. It provides a forum where leaders can discuss fundamental issues, find common ground and provide guidance to their negotiators.
The secretary-general urged developed nations to take the first steps forward.
"If you do so, others will take bold measures of their own," Ban said, adding that developing countries should also accelerate their efforts. "All countries must do more -- now."
The day-long event opened with the recitation of a portion of late U.S. astronomer Carl Sagan's Pale Blue Dot by actor Djimon Hounsou, a two-time Academy Award nominee, followed by a film both written and narrated by children from around the world.
President Barack Obama of the United States, President Mohamed Nasheed of Maldives, President Hu Jintao of China, Prime Minister Yukio Hatoyama of Japan, President Paul Kagame of Rwanda, Prime Minister Fredrik Reinfeldt of Sweden, President Oscar Arias Sanchez of Costa Rica, and President Nicolas Sarkozy of France spoke at the opening session.
Also addressing that session was Rajendra Pachauri, who chairs the Nobel Peace Prize-winning Intergovernmental Panel on Climate Change (IPCC), warning of the dangers of inaction on climate change.
"If we take no action to stabilize the concentration of greenhouse gases in the atmosphere, then average temperature by the end of this century would increase anywhere from 1.1 degrees to 6.4 degrees C," Pachauri said.
Between 1970 and 2004, global emissions increased by 70 percent and carbon dioxide by 80 percent, he said. "We must halt this unacceptable trend."
An uncontrolled climate change will bring about disastrous consequences such as rising sea levels, extreme weather patterns, scarcity of water and food resources, and even the submerging of several small island states, he warned.
Compared to the damage, the cost of mitigation is "modest," not exceeding 3 percent of the global gross domestic product (GDP) by 2030, Pachauri said.
After the opening session, world leaders met in eight closed roundtables throughout the day, to discuss possible actions that can help the negotiations reach a successful outcome in Copenhagen.