China sent a strong signal of its willingness to step up its measures on climate change as President Xi Jinping announced on Saturday more commitments by the country to tackle the global climate challenge at a virtual summit celebrating the fifth anniversary of the Paris Agreement.

Speaking via video link at the Climate Ambition Summit, Xi said that by 2030 China will lower its carbon dioxide emissions per unit of GDP by over 65 percent from the 2005 level and increase the share of nonfossil fuels in primary energy consumption to around 25 percent.

China will also increase its forest stock volume by 6 billion cubic meters from the 2005 level, and bring its total installed capacity of wind and solar power to over 1.2 billion kilowatts, he said.

"China always honors its commitments," Xi said, adding that the nation will take solid steps to implement the announced targets and contribute even more to tackling the global climate challenge.

Xi said China has made important contributions to adopting the Paris Agreement and has made active efforts toward implementing it.

The new commitments came after Xi announced in September that China would scale up its nationally determined contributions and adopt more vigorous policies and measures to peak carbon dioxide emissions before 2030 and achieve carbon neutrality before 2060.

Addressing the online summit, Xi urged all parties to close ranks and make new advances in climate governance that feature win-win cooperation.

In meeting the climate challenge, no one can be aloof, and unilateralism will lead nowhere, he said. "Only by upholding multilateralism, unity and cooperation can we deliver shared benefits and win-win results for all nations."

"China welcomes all countries' support for the Paris Agreement and their greater contribution to tackling climate change," he added.

Xi also called for raising ambitions and fostering a new architecture of climate governance where every party does its part, saying that developed countries need to scale up support for developing countries in financing, technology and capacity building.

Following the principle of common but differentiated responsibilities, all countries need to maximize actions in light of their respective national circumstances and capabilities, he said.

Xi also urged all parties to boost their confidence and pursue a new approach to climate governance that highlights green recovery. China, guided by the new development philosophy, will promote greener economic and social development in all respects while pursuing high-quality development, he said.

"Mountains and rivers green are mountains of silver and gold," Xi said, adding that it is important to encourage green, low-carbon ways of life and production, and seek development opportunities and impetus from green development.

The commitments by Xi demonstrate the seriousness and readiness of China to be a leading power in climate change and show credible commitment to the Paris Agreement as a sizable part of international law, said Christopher Bovis, a professor of international business law at the University of Hull in the United Kingdom.

"In the Climate Ambition Summit, President Xi has declared a new vision and commitment to the Paris Agreement on climate change by adopting multilateralism as the recipe for renewed international climate governance," Bovis added.

By adopting such as governance system, common yet differentiated responsibilities should be allocated to developed and developing countries respectively to combat climate change and promote a recovery which is based on sustainable, low-carbon and green production factors, he said.

"Multilateralism and differentiated responsibilities and obligations will result in a new development framework where technology transfer, financing and investment patterns will aim at capacity building of developing countries … to facilitate their pathway towards sustainable economic development," Bovis said.

Last month, Xi reiterated China's commitment to global climate action when addressing several multilateral occasions including the third Paris Peace Forum and the Leaders' Side Event on Safeguarding the Planet of the G20 Riyadh Summit.

The president's latest pledge showed that China, as a responsible major country, is committed to building a community with a shared future for mankind, said Li Zheng, executive vice-president of the Institute of Climate Change and Sustainable Development at Tsinghua University.

Compared with the targets China announced in 2015 to lower carbon intensity by 60 to 65 percent by 2030, China has scaled up its nationally determined contributions in the latest commitments announced on Saturday.

The nationally determined contributions－efforts by each country to reduce national emissions and adapt to the impacts of climate change－are at the heart of the Paris Agreement.

A 2019 report from the UN Environment Programme said that "if we rely only on the current climate commitments of the Paris Agreement, and they are fully implemented, there is a 66 percent chance that warming will rise to 3.2 C by the end of the century". The target is to keep the rise below 1.5 C.

Li from Tsinghua University said the post-pandemic recovery must be a green recovery in response to climate change.

"By developing green infrastructure such as renewable energy, intelligent transportation and smart grid, people could make full use of the green transition as a new economic driver," he said.

Xinhua and Wang Mingjie in London contributed to this story.