Longyangxia Dam Solar Park in Chinas Qinghai province. Photograph: Tom Phillips for the Guardian
Last September campaigners hailed a major victory in the war on global warming when China and the US jointly announced they would formally ratify the Paris agreement.
Our response to climate change bears on the future of our people and the wellbeing of mankind, Xi said, vowing to unwaveringly pursue sustainable development.
Ronen said: A decade ago, Chinas attitude was: You guys put all that carbon in the atmosphere growing your economy, we should be allowed to put a lot of pollution up there too to grow our economy. Now look at where we are.
Sam Geall, the executive editor of China Dialogue, a bilingual website on the environment, said Beijing viewed having a climate change denying US president as a rare and unexpected opportunity to boost Chinese soft power by positioning itself as the worlds premier climate change fighter.
[China sees it as] an opportunity for them to show leadership, he said. Ive already heard that from people who work in environment bureaucracy in China. They see this as an opportunity for China to step up.
Ronen said Chinas renewable revolution, which has seen sprawling solar and wind parks spring up across its western hinterlands, was part of a dramatic political U-turn that culminated in Beijing throwing its weight behind the Paris climate accord last year.
He said part of the explanation was air pollution repeated episodes of toxic smog have convinced Beijing it must take action to quell public anger and part was climate change.
They are very much impacted by a lot of these climate change weather patterns that are particularly troublesome: drought in the north, flooding they are very vulnerable to, Ronen said.
But Paulson Institutes Hove said the key driving force behind Chinas low carbon quest was economic.
Most of the things that China is doing related to the environment are generally things that China wants to do for the economy as well, he said, pointing to Beijings desire to rebalance the economy away from investment-led heavy industry-focused growth while simultaneously making itself the key player in an industry of the future and guaranteeing its own energy security.
Hove said Beijing saw a huge investment opportunity in exporting low-carbon technology such as high speed rail, solar power or electric vehicles to developing nations in Africa, south Asia and Latin America. This is a 20-30 year mission to develop [clean] markets, he said.
A recent report captured how China was already dominating the global clean energy market, pointing to billions of recent investments in renewables in countries such as Brazil, Egypt, Indonesia, Pakistan and Vietnam.
Xie, the Huanghe chairman, said his company was now making its first steps into Africa with solar and hydro projects under development in Ethiopia.
We are actively going global, he said, warning that the developing world could not copy the wests dirty development model without bringing about the destruction of the world.
Geall said one indication of whether China was prepared to become the worlds premier climate leader would be if it was seen helping to finance more low-carbon projects beyond its own borders such as a huge Chinese-built solar park in Pakistan.
Youd hope to start seeing more of those sorts of projects around the world being financed rather than [China being] just a source of cheap finance for dirty energy projects.
Not all are convinced China is ready or even willing to become the worlds top climate leader in a post-Trump world.
Zhang Junjie, an environmental expert from Duke Kunshan University, believed China would stick to its Paris commitments out of self-interest, particularly since the fight against global warming empowered its environmental agencies to crack down on toxic smog despite strong resistance from vested interests.
[But] if China needs to do more, to commit more, I dont expect that is likely, Zhang added, noting that China wanted to be a climate leader but not the climate leader. Leadership is not just power it is responsibility.
With Chinas economy losing steam, Zhang said tightening regulations on greenhouse gas emissions further would inflict major trouble on its manufacturing sector. Chinas clean industries were not sufficiently developed to provide jobs for all those who would be made unemployed as a result. I would say, dont count on [China to fill the gap left by the US], he said. China has its own troubles now.
Chinas push to develop renewables has not been entirely plain sailing either, with concerns about over-capacity, falling demand for electricity and curtailment, the amount of energy that is produced but fails to make it to the grid.
Hove said despite the rapid growth of the sector, wind still accounted for just 4% of Chinas electricity last year and solar for about 1%. Government subsidies meant many of the biggest solar and wind parks had been built in sub-optimal locations such as Qinghai, Gansu and Xinjiang, far from the southern and eastern metropolises where the energy was most needed.
Those behind the worlds largest solar park admitted obstacles such as energy wastage and transmission had yet to be overcome, but said there was no looking back as China forged ahead towards a low-carbon future.
New energy is surely the future … Its hard to predict the future but I believe that solar energy will account for 50% of the total in 50 years, said the engineer Gu.
Xie said authorities in Qinghai were now so confident the future of China was green that they were planning two massive new solar parks on the Tibetan plateau, with the capacity to produce 4GW of energy.
In a sign of the central governments support for the renewable revolution, Xi recently visited Xies company, urging staff to make every reasonable effort to develop the PV industry.
Xie, who hosted the Chinese president, scoffed at Trumps suggestion that climate change was a Chinese hoax and said such claims would do nothing to dampen his countrys enthusiasm for a low-carbon future.
Even if President Trump doesnt care about the climate, thats Americas point of view, he said. The Chinese government will carry out and fulfil its international commitments as they always have done in the past, and as they are doing now in order to try to tackle climate change.
Xie concluded: I dont care what Mr Trump says I dont understand it and I dont care about it. I think what he says is nonsense.
Additional reporting by Wang Zhen