Science & the Public

Janet Raloff
Science & the Public

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The United States is always held up as the leading polluter of carbon dioxide—the most important greenhouse gas. Well, no more, according to researchers at the University of California. Their calculations indicate China’s releases began exceeding ours more than a year ago—or 14 years earlier than many scientists had initially predicted.

Projections of China’s likely greenhouse-gas emissions have tended to start with data from around the 1990s. Then computer modelers applied some escalator factors to account for the expected growth in incomes and smokestack industries since the ‘90s. A growing economy would be expected to drive a fairly predictable increase in CO2 pollution, especially in a fossil-fuel-based economy like China’s.

The problem: China’s economic development has skyrocketed. The growth in personal and industrial incomes has far exceeded the roughly 5 percent per year that had once seemed reasonable, report Maximilian Auffhammer of UC Berkeley and Richard T. Carson of UC San Diego. Indeed, the growth since 2000 in China’s gross domestic product has been closer to 11 percent, they point out in an upcoming issue of the Journal of Environmental Economics and Management.

’s “abandonment of energy efficiency programs in favor of economic growth has resulted in an unprecedented increase in emissions of local air pollutants and correspondingly greenhouse-gas emissions,” they report.

The UC researchers modeled China’s releases based on province-level data that is annually updated and publicly available. They argue that “This feature is a main advantage over forecasts using infrequently updated sources of data.”

However, one “concern” in using such official statistics from developing countries, such as China, Auffhammer and Carson acknowledge, “is that chronic underfunding of data collection agencies may lead to fabricated data.” The UC team attempted to evaluate the likelihood that it was relying on particularly skewed data by communicating directly with Chinese officials. Those officials had been reporting releases of a composite pollutant described only as “waste gas emissions.” The UC researchers found out how the officials calculated these, and then used this value, which is based on fuel use, as a “proxy for CO2 at the province level.”

Westerners might have predicted that the biggest emissions would trace to activities in Beijing. Not according to the new analysis. Based on projections from 2004 waste gas emissions, the top greenhouse-gas polluting provinces were Inner Mongolia, followed by, in order, Shanghai, Shanxi, Ningxia, Hebei, Liaoning, Tianjin, Zhejiang, Jiangsu, and Guangxi.

Of course, it’s misguided to lay all of the blame for China’s skyrocketing greenhouse-gas emissions on China. After all, consider who has been buying the goods that China’s burgeoning manufacturing industry has been churning out? Can U.S. consumers even lay their hands on a new kitchen appliance, television, pair of sneakers, or lamp from anywhere but China, these days?

America, in a sense, has shifted the pollution associated with its consumption patterns from smokestacks at home to smokestacks overseas. Sure, China’s growing middle and upper classes will soon put plenty of pressure on the production of these goods for their own use. But we gave them a good head start.

As with so many things, pollution has a multinational cause in addition to a global effect. It’s time we all evaluated how much we need and whether there are relatively low-resource options to meeting those needs.


Auffhammer, M. and R.T. Carson. 2008. Forecasting the Path of China's CO2 Emissions Using Province-Level Information. Journal of Environmental Economics and Management (in press).

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