With our planet under pressure from human activity and ecological constraints, noted author and economist Jeffrey Sachs says we have entered - by necessity - "The Age of Sustainable Development."
"We can't just focus on economics alone," says Sachs. "We need to focus on economics, social inclusion... and on environmental sustainability."
Sachs recognizes China's success in ending extreme poverty over the last three decades. And he commends the country for bringing big investment to Africa.
But China has a huge challenge ahead if it wishes to develop sustainably.
"It's done great on economics but on the environment? This is the next challenge," he says.
"China is a coal-based economy and coal is a huge problem for air pollution and carbon dioxide that changes the climate."
Because in the end, prosperity alone isn't enough for the people of China.
"They want happiness and well-being, and that means you can breathe the air and know you have the chance if you are poor that your child can get ahead," says Sachs.
Click on the video above to hear more about the balance that China and the world must strike to achieve sustainable development in the 21st century.