While turmoil in Europe appears to be the major factor driving down markets today, Asian indexes also dropped overnight, weighing further on the Dow Jones Industrial Average (INDEX: ^DJI). The Hang Seng (INDEX: ^HSI) declined nearly 2% as the April HSBC/Markit Economics purchasing managers' index came in at 49.1, indicating a contraction in manufacturing. The figure was an improvement over March's 48.3, but still evidence of a slowing Chinese economy.

The news has driven down commodities markets as oil dropped nearly 2% and copper was down more than 2%. The looming austerity measures in Europe have compounded the reaction to China's slowdown, as the EU is its biggest export market.

The manufacturing numbers are just one of many recent reports indicating that China's rocket-like growth is finally losing steam. Its first quarter, GDP growth of 8.1% marked the lowest rate in three years and a drop from 8.9% in the fourth quarter of 2011. That figure was less than economists' prediction of 8.3%. Chinese officials have also shifted toward policies encouraging growth driven internally by consumer demand rather than by manufacturing and exports. Inflation has come with the GDP growth as well as an unsustainable housing boom, and the government has indicated that it will make moves to encourage more bank lending, which should help small-business development and domestic consumption. Beijing has set a target of 7.5% GDP growth for the year.

Not surprisingly, China's manufacturing slowdown has affected Dow cyclicals like Alcoa (NYSE: AA) and Caterpillar (NYSE: CAT) more than the most. Alcoa is the largest multinational aluminum investor in China, having invested $800 million since 1993. In its first-quarter report released earlier this month, the aluminum-maker reduced its projection for Chinese aluminum demand by 1 percentage point to 11%, down from 15% in 2011. Speaking recently, CEO Klaus Kleinfeld cast doubt on the Chinese aluminum industry, saying much of its production is subject to costs above industry averages and its plans to expand production in western China were likely to disappoint.

Meanwhile, China should factor into Caterpillar's prospects when it reports earnings on Wednesday. The company has 17 plants and nine more under construction in China, its largest market. Overall sales of excavators, a key product category, dropped nearly 50% in that country during March, a concern for some in the construction equipment business (though that figure could turn around by this summer). Caterpillar has lost market share in excavators over the past five years. Also in March, the company said it would expand hydraulic excavator production by 80% in China. At the beginning of the year, Caterpillar had predicted 10% growth in construction equipment demand for 2012. Analysts are expecting earnings of $2.13 per share when the manufacturer reports later this week. That figure would be a 16% improvement over profits a year ago.

More ideas for growth
Despite China's slowdown, it still represents the biggest growth opportunity in the world, and not just for manufacturers like Alcoa and Caterpillar. American brands have become extremely successful there due to their quality products and China's burgeoning culture of "conspicuous consumption" as it embraces free market ideals. Our experts at the Fool have found a group of companies branching out into emerging markets and reaping the rewards. Find out what these hot stocks are in our special free report: "3 American Companies Set to Dominate the World." You can get your copy by clicking right here.