A key barometer of economic health is flashing more warning signs for China's economy

• Copper demand in China is lagging at a time when consumption is usually elevated, Bloomberg wrote.
• Profitability among copper smelters has dropped by the lowest in over a decade.
• Less demand in the bellwether commodity demonstrates more trouble for China's economy.

China's demand for copper is lagging at a time usually defined by higher demand, Bloomberg reported.