America's use of aluminum, copper, lead and other processed metals is declining sharply, a top U.S. Interior Department official said yesterday, calling the trend worrying in the face of skyrocketing Chinese production, consumption and stockpiling of mineral resources.

Asked at a U.S.-China Economic and Security Review Commission hearing what keeps him "up at night" with worry, W. David Menzie, chief of the U.S. Geological Survey's global minerals analysis section, cited domestic decline.

"I think that's an indication of the front end of the supply chain," Menzie said. "If you need a particular item at the end of the supply chain and you don't have secure supplies ... then you have vulnerabilities."

The hearing before the congressionally mandated commission charged with monitoring and investigating the relationship between the United States and China comes amid heightened concern about China's export restraints on rare earth minerals.

China manufactures more than 80 percent of such minerals as lutetium, terbium and dysprosium, which are then used in everything from smartphones to hybrid car batteries. But export quotas that China is attempting to impose on such resources have raised the ire of U.S. trade officials, who have threatened to bring the issue to the World Trade Organization.

Meanwhile, experts from across a spectrum of fields told the commission yesterday, China's skyrocketing growth is gobbling up other precious resources, like water, at a startling pace. The impacts of climate change along with fast-paced growth have led to water diversion projects that threaten to cause unrest within China as well as with neighbors in India and elsewhere, said Jennifer Turner, director of the China Environment Forum at the Woodrow Wilson International Center for Scholars.

Growing use of water to produce coal

She noted that water consumption has increased only marginally in China -- yet 20 percent of the country's water is being used to produce coal. Meanwhile, a particularly sensitive massive water transfer project that ostensibly is being used to address the needs of northern Chinese cities is also being used to feed coal.

"Coal is king, and the king is thirsty," Turner said, predicting that tension with India over water ultimately "boils down to coal." She urged the commission to encourage the United States to work with China to address energy efficiency as well as the nexus between energy, water and agriculture. "Low carbon could mean low water," she said. "I think there needs to be much stronger emphasis on the water issue."

Meanwhile, Mikkal Herberg, research director of the National Bureau of Asian Research's Energy Security Program, said China's desire for energy security is at the heart of its strategy for securing resources like oil beyond its borders.

"Energy security is a visceral concern for leadership in China. They believe it's an Achilles' heel that could potentially undermine economic growth," Herberg said. The country now imports about 50 percent of its oil needs, a figure that is expected to rise to 75 percent. "This is deeply unsettling for the leadership in Beijing, and this is what drives the impulse for this 'go-out' strategy," he said.

Herberg argued that China's moves to secure energy overseas may affect prices but ultimately does not undermine America's energy security. Yet when it comes to rare earth minerals, Jeff Green, a rare-earth mineral lobbyist, said China's dominance indeed poses economic and security risks. He said the United States has for too long employed an "ad hoc approach" to securing critical resources and argued for a comprehensive government plan to define such materials, incentivize extraction in the United States and pursue World Trade Organization actions against China.

Commissioner Richard D'Amato agreed. He pointed to China's halting last year of rare earth exports to Japan in retaliation for Tokyo's arrest of a Chinese fishing boat captain near disputed islands as reason to examine U.S. vulnerability.

"Obviously, the Chinese are willing to use it as a political tool," D'Amato said of the country's rare earth dominance. Meanwhile, he said, the Obama administration appears to be addressing overarching national security concerns linked to U.S. resource dependency on China "at a sleepy pace."

"I'm not too impressed right now with the level of attention to this problem," he said.