Economic abundance, however, has resulted in the scarcity of blue skies and white clouds, something I enjoy every day while passing by Connecticut Avenue Bridge near my apartment.

China may be one of the largest importers in the world, but nobody wants it to reach a point where it has to import, and in large volumes, clean air, soil and water.

Over the past few decades, polluting the environment - air, soil water, et al - has been the least costly thing to do in China. Many factories discharge sewage and toxic waste, without caring to treat them, into the atmosphere, soil and water bodies.

Everyone is probably richer now in terms of disposable income, but the cost of achieving higher income has been high, so high that our children, grandchildren and great grandchildren will continue to pay it even long after we are gone.

The good news is that China has realized that its economic development model of the past three decades is not sustainable, given the cost it has extracted (and is extracting) from the environment. Premier Li Keqiang has emphasized building an "ecological civilization" to move up the economic value chain.

However, the colossal challenge China faces on the environmental and ecological front is far greater than any of its other challenges, such as the real estate bubble, unemployment or even corruption.

In most parts of China, hardly are environmental laws enforced effectively enough to prevent individuals and businesses from breaking or trying to break them.

If we still do not act, we will never see blue skies and fluffy white clouds in Shanghai, Beijing and other cities in China.

The author, based in Washington, is deputy editor of China Daily USA. chenweihua@chinadailyusa.com