The importance of China for the global economy cannot be over-stated. First there is sheer size. China is the second largest economy in the world and a significant importer of commodities such as copper and oil.
Second, the world has come to expect Chinese economic growth rates of 10-12%, growth rates that have helped bolster the world economy especially during turbulent times in Europe and the U.S. But now Chinese growth is slowing, and there are significant concerns about the health of the Chinese financial system.