This column originally appeared on Real Money Pro on Sept. 5.NEW YORK ( Real Money) -- Over the past few weeks, I have spent a lot of time writing about the weakening Chinese economy, a potential canary in the world's economic coal mine. Last night, China's August Nonmanufacturing Index chimed in at a below-consensus 52.0 vs. the prior month's 53.1. This is the lowest print in several years and, importantly, suggests that third-quarter 2012 real GDP consensus forecasts (and China's official target) of 7.5% growth is unattainable. It now appears that China's third-quarter real GDP growth might be 6.5% or lower. Although the Chinese stock market is in bear market territory, to date, China's economic disappearing act has had little influence on the world's markets. The rapidity of the decline in economic activity, however, is probably now at the tipping point for the world's non-Asian stock markets. Looking forward, China's leadership change next month should be met with more monetary easing. It might be too late.