The United Nations Climate Summit in New York on Tuesday provided a front-row seat to how world leaders perceive the threat of global warming and set the stage for the signing of a new global climate agreement in Paris, China Daily reports.

The scene was New York this week, but the goal is Paris in 2015.

On Sunday, an estimated 400,000 peaceful demonstrators marched through Manhattan's streets in a show of "people power", urging government leaders to tackle global warming. And they marched in more than 160 countries around the world, including London, New Delhi and Melbourne, Australia.

"The People's Climate March" was held on the same day that a report from scientists showed that the world remains far from controlling global warming. Global emissions of greenhouse gases had jumped 2.3 percent in 2013 to record levels.

The march was keyed to the United Nations Climate Change summit. The one-day assemblage of more than 100 world leaders on Tuesday was called by UN Secretary General Ban Ki-moon to provide momentum for 120 member states to sign a comprehensive new global climate agreement at talks in Paris next year.

At the opening session, speakers included former US vice-president and environmental activist Al Gore; chairperson of the Intergovernmental Panel on Climate Change Rajendra Pachauri; Chinese actress and United Nations Environmental Program Goodwill Ambassador Li Bingbing; and Hollywood actor and newly appointed UN Messenger of Peace Leonardo DiCaprio.

The summit's main speakers represented the two biggest carbon emitters in the world: China and the United States.

Chinese Vice-Premier Zhang Gaoli said China, the world's No 2 economy and most populous country, is ready to work with other countries to fight climate change.

"This is not at others' request but on our own initiative," he told the gathering.

As Chinese President Xi Jinping's climate-change envoy, Zhang said: "We will continue to share international responsibilities to address the climate change issue, including a greater effort to peak greenhouse gas levels and increasing financial help to a South-South cooperation fund."

"We will announce post-2020 actions on climate change as soon as we can, which will bring about marked progress in reducing carbon intensity, increasing the share of non-fossil fuels and raising the forest stock," Zhang said.

The action plan will also take China to the peak of its total CO2 emissions as early as possible, said Zhang.

President Barack Obama said the US would meet a pledge to cut its carbon emissions by 17 percent from 2005 levels by 2020. And he said the US is preparing new targets to cut emissions further by 2050 with specifics to be made public at the meeting in Paris.

At the end of the session, UN Secretary-General Ban Ki-moon declared it a success. "We have delivered," he said.

Not so fast, said the widow of Nelson Mandela.

"There is a huge mismatch between the magnitude of the challenge and the response we heard here today," Graa Machel said. "The scale is much more than we have achieved."

She said the leaders had failed to offer an adequate response to the hundreds of thousands of people who marched on Sunday and the millions in poor countries who will suffer its effects.

"Can we genuinely say we are going to preserve their lives, and ensure their children and grandchildren and great-grandchildren inherit a planet which is safe and sustainable?" she asked.

Machel appealed to world leaders and business executives to "go back to the drawing board". "The obligation in my view is to step up the ambition," she said.