Xie then served as head of the country's national environmental authority from 1993 to 2005 before moving to the National Development and Reform Commission as deputy director in 2006.

Jia said Xie's good reputation as a climate diplomat was a result of his character, and also the consistency of the country's climate policy.

He described Xie as a trustworthy people person who was adept at listening, had a fine sense of humor and always adhered firmly to principles.

Listening is key in international negotiations, Jia said, because the parties involved cannot reach a consensus without learning about the stances of other delegations. Other parties should be given both opportunities and time to express themselves, he said.

"He is not a person who likes expressing himself," Jia said. "Usually, he squints at you with a smile. He listens quietly. At times, he utters a few words that make people feel at ease."

He said Xie was not the kind of speaker who could spark an enormous belly laugh among listeners, but instead exhibited a more deadpan sense of humor, giving the climate diplomat's response to a reporter from The Associated Press at COP26 in the United Kingdom in 2021 as an example.

"Would it be possible to answer in English?" the reporter asked, as Xie blinked his eyes.

Xie shook his head five times, before his face bloomed into a big smile. He then stretched out his left hand in a leisurely manner and replied in Chinese: "How about you raise questions in Chinese?"

Many reporters burst into laughter after that exchange.

"Xie keeps his promises and treats others sincerely," Jia said, adding that senior climate diplomats from many other countries could not be as trustworthy because their governments were not as consistent as the Chinese government when it came to climate policies.

He said Xie had never wavered on issues concerning China's interests and the principle of common but differentiated responsibilities and respective capabilities, which is enshrined in the United Nations Framework Convention on Climate Change.

"He is a symbol that represents not only the credibility of China, the country's image of always honoring its commitment with concrete actions, but also representing the voices of developing nations," Jia said.