Rising U.S. Trade May Increase Carbon Emissions

A rise in global trade has researchers wondering about the potential impact on future climate policy.

A recent Carnegie Mellon study finds that the United States may be reducing its own carbon emissions by importing goods from countries that are creating even more emissions in the production process than the United States would have originally.

Making a desktop computer in China, for example, can generate up to three times the carbon dioxide emissions as making the same desktop computer in the United States.

Carnegie Mellon researchers Christopher L. Weber and H. Scott Matthews note that, overall, carbon dioxide emissions associated with imports rose from 12 percent of total U.S. emissions in 1997 to 22 percent in 2004. Weber and Matthews stress this is a substantial increase considering that the United States already emits about 25 percent of the world's total global carbon dioxide.

These emissions are only going to increase as the United States continues to consume more and more essential goods from outside its borders," said Matthews, an associate professor in the departments of civil and environmental engineering and engineering and public policy (EPP).

While they urge the United States and other developed countries to agree to further reduction of greenhouse gases, Weber and Matthews acknowledge the many complexities that surround the issue.

"To ask the developing countries to lower emissions too early, too abruptly will hinder their development and hamper their efforts to achieve industrialization and modernization," said Matthews.

Weber believes the central question is one of responsibility.

"Over the last decade, the United States' share of global carbon emissions has gone down and China's has gone up," said Weber, a graduate researcher in the departments of civil and environmental engineering and EPP.

"However, if you count not by who makes the goods, but by who consumes the goods, the United States' share of responsibility has stayed constant or even gone up," he added. "But these emissions are not counted because they've been outsourced to other countries."

The June 2007 research paper is published in "Environmental Science and Technology." 

Related Links: Dept of Civil & Environmental Engineering  |  Engineering & Public Policy

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