With two-thirds of its energy still generated by coal, China produces and consumes almost as much of the fossil fuel as the rest of the world combined.
It's also China's biggest source of carbon emissions.
According to Greenpeace
, authorities have issued more than 150 permits to build new coal-fired power plants this year alone, despite the government's pledges to reduce China's dependence on fossil fuel.
"In the past decade... the capacity of coal-fired power plants that we've shut down is more than the nationwide capacity of Great Britain," Xie told CNN in an interview this week.
"As we close those backward and inefficient power plants, we have replaced them with more efficient, cleaner power plants -- and our total carbon emissions won't go up much."
The government recently revised up its post-2000 coal consumption figures, in some cases by 17% more per year than previously reported, alarming some experts who say the new data mean a billion more tons of carbon dioxide in the air.
But Xie said that China would still meet its target for emissions to peak in 2030.
That goal was spelled out in a landmark agreement
reached by China and the United States in November 2014 when U.S. President Barack Obama met with Chinese leader Xi Jinping in Beijing.
"Our emission reduction targets were under discussion for two years," Xie said. "We had learned those new figures during the process and already factored them in."
During the same period, "our hydropower capacity doubled, wind power capacity increased 60-fold and solar power capacity soared 280-fold," he added.
"These sectors have been developing very fast and had a great impact on cutting the cost of renewable energy globally by over 50%."
Bali to Paris
Xie has led his country's international negotiations at every gathering on the issue since the United Nations conference in Bali in 2007.
He jokes about coming to a full circle when he attends the upcoming COP21 Paris Climate Conference
-- as Bali and Paris are pronounced the same way in Mandarin Chinese.
Much has changed since Bali, however. China is now the world's second-largest economy as well as its biggest emitter of greenhouse gases, including carbon dioxide -- a major cause of global warming.
Beijing has long insisted on the principle of "common but differentiated responsibility" in dealing with climate change, under which developed nations must cut emissions more quickly as well as provide funding and technical know-how to developing countries.
"As China gradually completes its industrialization, carbon emissions from industries may reach their peak earlier than expected -- but the country still has a long way to go when it comes urbanization," Xie said.
"So emissions from construction, transportation and service sectors will keep rising. Looking at the broader picture, we feel the goal of having emissions peak around 2030 is a scientific one."
Trained as a physicist, Xie, 66, knows his numbers and statistics. As a former minister of environmental protection, he has seen the country's worsening air pollution -- which shares the same causes as climate change -- become a lightning rod for discontent.
Xie brushes aside concerns about the impact of China's economic slowdown on its climate change commitments, reiterating the government's determination to fight an uphill battle to hit its targets.
"Dealing with climate change is an inevitable road that we need to take to achieve sustainable development," he said. "This is not something we are pressured to do -- it's something we want to do and do well."
The usually loquacious and jovial Xie remains optimistic about the outcome in Paris, predicting a global agreement that would be "satisfactory to no-one but acceptable to everyone."
He does seem to have one serious concern, though.
"I'm actually worried that, after the next U.S. presidential election, if a Republican wins, will the United States keep its commitment to the climate change issue?" he asked, referring to skepticism of the science behind climate change in the field of GOP candidates.
"You don't have to worry about China's commitment. It's the United States that you should be concerned about -- will it keep its current policy intact? That's what worries me."