Erik Solheim, the former United Nations under-secretary-general and former executive director of the UN Environment Programme, has visited China many times since 1984 to witness the "unprecedented" changes in human history.

These include what he called "a sea change" in China in the last five to 10 years on the environment and climate change front.

"It's true that if you go back 10 years, Chinese cities were among the most polluted in the world. Then people demanded change, and the leadership responded," Solheim said.

The Norwegian politician believes that leadership is the most critical factor in dealing with the environment and climate challenges.

"Nations under good leadership have prospered and developed extremely fast. Nations with poor leadership have huge difficulties," he said.

Solheim, who once served as Norwegian minister for international development and minister for environment, praised China's political structure as a "very capable and merit-based" one, clearly referring to leaders who rise to the top after working many years at various levels of local governments.

He said that the political systems in China, the United States and Europe are different, but they should respect each other and work together.

He regretted that not many people in North America and Europe understand the huge achievements China has made on the environment and climate front, saying that China is now a world leader in terms of basic environmental technology from solar power to electric cars to high-speed rail.

He described China's efforts to protect wetlands and vulnerable ecosystems in heavily populated areas as "very difficult and challenging" and a "world-class development".

"In terms of these practices, China is one of the leaders of the world," Solheim said, citing the examples from Suzhou to Shenzhen as "among the greenest and environmental friendly" cities.

Solheim said he wanted to tell the deputies and members to the ongoing annual sessions of the National People's Congress and Chinese People's Political Consultative Conference National Committee that the environment and climate fight will be a win-win-win, exactly as President Xi Jinping said that "Green is gold".

He elaborated that the triple wins mean win ecologically, win economically, including creating jobs, and win socially now that people bid farewell to pollution and live better lives.

The former senior UN official believes it's possible for major global players, such as China, the US and the European Union, to work together on climate change. He said that such cooperation will benefit everyone and that no area is riper for cooperation than on environment and climate.

"Because there is only one planet. We are in this together," Solheim said.

"We should aim at cooperation and competition, but no confrontation."

He is "very optimistic" about the cooperation because "we have a once-in-a-generation" opportunity to tackle the challenge. He said that while public opinion demands green change, political leaders now in China, the US and EU all want to move faster in the green direction.

Solheim, who has a rich knowledge of China, hopes the Western world will show more respect and curiosity toward China and learn its rich and long history and civilization, while the Chinese should heed the views from the other side.

He called China's recent announcement of eradicating extreme poverty as "probably the biggest change of this century". "It should be celebrated by all, but not many articles talked about that," he said, lamenting that Western media's portrayal of China was "largely negative".