You could say it started with a little bit of food. Too little, as it turned out. Short supply and high demand for fruits and grains created historic bursts in food prices around the world. In the Middle East, where food accounts for 40% of spending, it fed political unrest. Revolution spread to Libya, whose crude crisis led to a surge in global oil prices. Expensive gas tag-teamed with expensive copper and other commodity inflation in India and Brazil. Meanwhile, debt crises restrained growth in Europe, an earthquake set back Japan, and the U.S. recovery found more walls to hit.

It's no surprise that the global recovery is facing a new round of setbacks, as the IMF reported in a new report issued today. But after high food prices, slow growth, and heavy debt, there's another potential force emerging that could block the global recovery.

This one starts with metal. Too much, as it's turning out. China's property market is showing signs of rusting. Home buys in major cities are slowing down. Construction outside China's largest cities has infamously produced dozens of "ghost" towns that are actually more like stillborn cities, because they were designed for residents that never materialized (images and commentary via Gus Lubin at Business Insider):

The People's Bank of China has raised interest rates four times in the last two years and raised bank deposit requirements 11 times since January 2010, reports Caixin, a Chinese business magazine. This will slow down investment and make it more difficult for the country's emerging middle class to move out to these theoretical cities. Few analysts are anticipating a full-scale meltdown of the Chinese housing market. But even a moderate dip reverberates.

You can't keep an economic crises a national secret. As we've seen, Greece's debt problem is Europe's currency mess is the world's financial crisis. Similarly, China's housing problem is Latin America's commodity mess is the world economy's crisis. China gobbles up half of some of the world's highest selling metals. A dip in demand hurts Australia (coal, iron ore, natural gas), South Africa and Brazil (industrial metals) and Chile (copper), Alex Frangos of the Wall Street Journal writes. A slowdown in demand would send ripples in all directions. Currencies in Australia, Brazil, Chile peso would decline. Ditto industrial production out of South Korea, Taiwan and Japan.

This isn't meant to be histrionic or dire. (In the department of silver linings, a slowdown in China might ease commodity inflation. If Beijing lets its currency appreciate, it would bring trade into equilibrium in southeast Asia. And so on.) It's meant to be realistic. Seven months ago, analysts were predicting 2011 would be the Year of America. It was unthinkable that food inflation could help spark an Egyptian revolution that bled into Libya, shocking oil prices, which helped constrain growth for the first six months of the year. China's empty homes are worth watching.