The sheer scale of China's economic transformation is matched only by the size of the new challenges and dangers it has created.
None is bigger than the threat to the environment.
Feeding a fifth of the world's people on 7% of its arable land was never easy - and that land is now shrinking at a rate of 1m hectares a year.
Economic growth has transformed China
"If you travel out of town you don't find any countryside at all anymore," complains one resident of Shanghai. "Just more cities".
The endless grey factories and tower blocks of China's development zones are soaking up the biggest rural migration in human history.
The plan is to move as many as 400 million people to the cities in the next 25 years, people who will need new roads, housing and other infrastructure on a truly massive scale.
Such is China's economic frenzy that a country which was once almost self-sufficient now imports not only grain but also huge quantities of other resources. It is the world's largest consumer of copper, aluminium and cement and the second biggest importer of oil.
While this appetite sparks fears about the long-term effects on the world's raw materials, China's own natural resources - its air, land and water - are already suffering badly.
China has already become the world's second biggest generator of carbon dioxide emissions and could overtake the US as the biggest source of greenhouse gases in three decades.
Already relying on coal for 75% of the country's energy needs, the government has responded to a series of power blackouts by building new, mainly coal-fired power plants, raising the prospect of ever more coal dust and acid rain.
Beijing is trying to reduce air pollution by urging residents to switch their heating to natural gas. But the huge rise in the number of cars on city streets does not help.
Car ownership has been doubling every few years. If per capita ownership were to reach US levels, China would have to find room for 600m cars - more than exist today in the entire world.
Turned to dust
Fly west from the capital and you get a bird's-eye view of perhaps the most serious threat of all.
Dusty beds of dried-up rivers run through endless grey hills and deserts below.
'Destroying is easy,' Dai Qing says
More than half China's citizens face serious problems of water shortage or contamination.
"When I was young, water was everywhere," said Dai Qing, a prominent writer.
"The edges of Beijing were rich with lotus-ponds and rice fields. But now it's totally disappeared. The nearest water is more than 100m below ground. Yet people still want houses with swimming pools, like in the US," she said.
Dai Qing led an unprecedented campaign against the Three Gorges dam on the Yangtze river. Now in its last phase of construction, the dam is set to be the world's largest hydroelectric project, generating power for China's expanding cities, and protests among critics.
There have already been many problems with sedimentation and flooding, she said. "But China's top leaders have prevented any mention of these in the media - even on the internet where they have their own police."
Upstream from the Three Gorges, the city of Chongqing hopes to benefit from the dam because big ships will be able to reach it from the coast.
But with China home to 16 of the 20 most polluted cities in the world - according to the World Bank - and Chongqing prominent amongst them, the great river is sometimes scarcely visible through the smog.
The city also faces serious sanitation problems, because its sewage and waste water goes straight into the river - a situation that is only now being addressed.
"In the dry season when the flow is less, the waste doesn't dilute as fast, so it becomes a health problem," said John Aspinall, who is helping supervise construction of a sewage treatment plant.
China's economic reforms have benefited hundreds of millions of people, giving them a better diet and better standard of life.
But while attention focuses on the damage done to China's natural resources as a cost of those reforms, the harm done to its most vulnerable people should not be overlooked.
Tackling the problems will take generations
Michael Ma, an environmental business consultant, has found Chinese workers packed into dark, smoky factories in scenes he describes as reminiscent of 18th century Europe.
"Some multinationals are as guilty as local companies of taking advantage of loose environmental and labour controls", he said.
"They find loopholes so they can make quick money. And if there's any problem - they just move deeper into the countryside."
Despite the scale of the challenges China now faces, all is not gloom.
There seems to be a new public awareness building of the dangers of destroying the resources on which China's long term health and prosperity depend.
Pressure from small grassroots groups has also achieved some limited success, raising hopes that the environment could be an issue that encourages the government to become more generally accountable.
Beijing has announced a series of tree-planting and other campaigns, although the State Environmental Protection Administration refused repeated requests for an interview to discuss them.
There are now proposals to make it more expensive for companies to pollute than not to pollute - and to make environmental issues a factor when local officials' promotion prospects are assessed.
But undoing the damage caused by breakneck growth will need more than that.
"Destroying is easy", Dai Qing said, "protecting and treating are difficult".
This is the third article in a series about change in modern China. Click below for the first two: