President Hu Jintao Tuesday told a huge gathering of world leaders that China will spare no effort in ensuring a deal is reached at the UN climate change meeting in Copenhagen.

Hu said China will fight for a "significant cut" in carbon emissions while urging developed countries to help other developing nations.

He made the commitment during a one-day summit on climate change in New York. The session was attended by more than 100 heads of state and government leaders, the largest gathering of world leaders seeking to address climate change.

The meeting was aimed at mobilizing political will to "accelerate the pace of negotiations and help strengthen the ambition of what is on offer," according to UN Secretary-General Ban Ki-moon.

While urging rich countries to transfer financial resources and technology to poorer nations, Hu said they should help equip African countries, small island nations, less-developed countries and land-locked nations adapt to climatic catastrophes.

"China will continue its unremitting endeavors in boosting energy efficiency and by 2020, we should try to achieve a significant cut of carbon dioxide emissions per unit of gross domestic product," Hu said.

Experts said it was the first time China's leader had described shifting China's policy away from energy intensity toward carbon management.

It was also the first time China had announced its mid-term goal of mitigating climate change, even though it has not yet added numbers.

"The pledge of a carbon intensity cut has been embedded with tremendous policy implications for China's future sustainable development," Daniel Dudek, chief economist with US-based Environmental Defense, told China Daily.

Dudek said Hu went to New York with new commitments.

"These announcements should sweep away the canard that China is not willing to reduce emissions," Dudek said.

The question now is whether China's pledges will propel the US Senate toward controlling global warming.

Dudek said 2020 will be an important year because it marks the beginning of the period in which scientists believe global emissions must peak if the world is to avoid devastating impacts of climate change.

"In this sense, a magnificent carbon cut in China by then would contribute mightily to turning global emissions from growth to reduction," said Dudek.

Hu also told world leaders China will seek to produce 15 percent of its energy from non-fossil fuel sources by 2020. Much of that will come from renewable energy and nuclear power.

He said the nation also plans to battle climate change by planting more trees and he committed to increase forested areas by 40 million hectares.

China will also develop a greener, low-carbon economy, encourage recycling and tap the potential of climate-friendly technologies.

But he insisted that, despite far-reaching social and economic improvements in recent decades, China is still a developing country.

And he said it is well down the global rankings of per capita GDP, with imbalanced domestic development.

"We have been faced with tough difficulties and we still have long way to go toward modernization," Hu said.

Despite its developing-nation status, he said China realizes the "toughness and urgency" of the fight against global warming and said the country has made great strides.

"And we will continue our unshakable efforts in fighting climate change," Hu said, while urging developed countries to make good on their Kyoto Protocol promise to cut emissions by 5 percent of their 1990 levels.

Hu said Copenhagen could be a milestone for the world while calling on developed countries to transfer technology and financial support to developing countries.

Yang Fuqiang, director of the global climate change solutions program at WWF, said China will intensify its domestic efforts to ensure it meets President Hu's promise to cut carbon intensity by 2020.

And Yang said the carbon intensity target is likely to be "quantified" before the Copenhagen climate summit.

"To fulfill this commitment, the country will include the carbon intensity targets ... in its 12th and 13th Five-Year Plans (between 2010 and 2020)," said Yang.

Yu Hongyuan, an associate professor with the Shanghai Institute for International Studies, said China has already started to draw up low-carbon economy guidelines and action plans to fight global warming at the provincial levels.

"This shows the carbon intensity goal proposed by President Hu is not beyond reach," said Yu.

The technology and experience China has built up will be of great assistance to less developed countries, Yang said.

With the carbon intensity cut, and improvements to the country's energy efficiency, Yang said China will slash 4.5 billion tons of carbon emissions between 2005 and 2020.