China's greenhouse gas (GHG) emissions have drawn attention in the United States because of their environmental and economic implications. China's actions to address climate change also hold implications for broader economic and security concerns in the United States. Scientific evidence that the Earth's climate is changing, and that human-related GHG emissions are a major driver of that change, has led to debate over whether and how to control GHG emissions. Once emitted, GHG persist in the atmosphere for years to centuries (and for some gases, millennia). They allow solar radiation to enter the Earth' system, but prevent much of the absorbed energy from escaping back out to space. Scientists agree that the Earth's atmosphere serves as a "blanket" that warms the Earth's surface and that a certain concentration of GHG is essential to maintain the planet at habitable temperatures. There is less agreement on how much warming would result from the higher atmospheric GHG concentrations expected if emissions from fossil fuel use, deforestation, and some agricultural and industrial processes continue. Scientific concerns in the 1980s led to initiation of inter-governmental discussions in 1989 to stabilize GHG concentrations and avoid potentially "dangerous" global temperature rise. These concerns led to negotiation of the United Nations Framework Convention on Climate Change (UNFCCC). In the late 1980s, climate experts broadly understood that climate change driven by human-related GHG emissions was a global challenge: all major emitting countries would need to engage in slowing then reducing their emissions of GHG as well as increasing GHG removals by "sinks" (e.g., growing forests). When the UNFCCC was opened for signature in 1992, the already industrialized countries emitted almost 80% of the global carbon dioxide (CO 2 ) from energy and industry. , The CO 2 emissions of the United States and the European Union were about 23% and 20%, respectively, of the global total. China's were about 11%. All the "developing" countries at the time contributed about one-third. Low income countries saw GHG-driven climate change as a problem made by the industrialized countries. Considering low income countries' challenged financial, technological, and governance capacities, they were not included in the UNFCCC's Annex I, which lists countries with quantitative GHG control targets for the 1990s. Nonetheless, the UNFCCC contained a principle of "common but differentiated responsibilities" among its Parties, with consensus that the already industrialized countries should lead in controlling their emissions and that all countries have obligations to address climate change. Annex I established a bifurcation between the Parties listed in Annex I and the Non-Annex I Parties. (Countries are frequently referred to as "developed" versus "developing," although the distinction is undefined and arguably a misleading simplification of the spectrum of differences among countries). Scientific analyses have concluded that rising GHG concentrations in the atmosphere cannot be stabilized unless all major emitting countries abate their net emissions to near zero. Despite efforts of many countries to reduce their GHG emissions, the continued and rapid growth of emissions from such large emitters as China and the United States has called into question the efficacy of the UNFCCC in meeting its objective of stabilizing concentrations of GHG in the atmosphere. As China's share of global GHG emissions has grown from about 11% in 1990 to about 21% today, and continues to grow, a broad set of observers have concluded that effectively slowing human-induced climate change depends on Chinese reductions of its emissions, as well as reductions from the United States and all other large emitters. U.S. congressional debate on potential climate change policies in the United States frequently invokes China's (and other emerging economies') surging greenhouse gas (GHG) emissions as well as skepticism over whether, how, and when China might alter that trend. Some are concerned that U.S. investment in GHG controls without comparable Chinese actions would unfairly advantage China in global trade, and fail to slow human-induced climate change. In contrast, others point to China's announced aggressive actions to reduce GHG emissions by deploying efficient and non-fossil fuel technologies, and warn that U.S. businesses could fall technologically and competitively behind China in the energy sector and international trade. Moreover, some suggest that Chinese policies may help buffer their production from rising and volatile fossil fuel prices, while the United States' production costs could remain subject to fluctuating world energy prices. Some experts point to the connections of China's GHG control policies to broader congressional concerns: China's role in world markets for energy, forest products, rare earth metals, and other strategic resources. Some analysts have noted that potential impacts of climate change on China's ecosystems, agriculture, water resources, and coastal zones could affect that nation's economic and political prospects, with both economic and security risks for the United States. This report lays a groundwork for congressional consideration of China's GHG policies. It describes the underlying economic and environmental context for China's GHG emissions then provides the magnitude and uncertainties of available estimates. It discusses the factors driving China's emissions and summarizes some of the best described elements of China's strategy to mitigate its GHG emissions. A brief section identifies key points on China's status in international cooperation. Over the past decade, the Chinese people and its leadership have come to view the country's economic well-being and its environmental quality as inextricably correlated. Figures for Gross Domestic Product without accounting for losses to air and water quality, human health, etc. exaggerated actual improvements in living standards. This has resulted in a shift to "harmonious growth" that tries to balance GDP growth with improving living standards. Between 1980 and 2009 the Chinese economy grew at an average annual rate of 10% (growing by factor of 16 over the period). In the past decade, China's annual growth rates varied between 8% and 14%, over which time its economy has tripled in size. China is now the second largest economy in the world, behind the United States. The country held $3.2 trillion in foreign exchange reserves by the June 2011. , Hundreds of millions of Chinese have improved their standards of living. These facts lead some to contend that China is no longer a developing country. Still, a recent World Bank report estimates that up to 200 million people (out of 1.3 billion) in China continue in poverty, living on less than $1.25 a day in 2005. The Chinese government perceives that its legitimacy depends on continuing to improve the living standards of its population. Its economic policies are stated to be strongly aimed at eliminating poverty and raising average incomes. China's achievements so far are reflected in Gross Domestic Product (GDP) per capita in 2009 of $6,800 in international dollars (int$), up 22% from 2007 and up 289% from 2000, according to the World Bank's World Development Indicators. Still, per capita incomes in China were about one-eighth those of Americans levels (respectively, int$5,594 and int$46,628). Table 1 provides selected economic, energy, and greenhouse gas statistics for China and the United States. In 2009, China's population was more than four times that of the United States, while its economy, as measured using "purchasing power parities," was just over half as large. Even with relatively slow population growth (0.5% annually) and high projected economic growth rates of at least 7% annually, it likely would take many years for the living standards of average Chinese to reach those of average Americans. China's national plans call for structural shifts in its economy. Much of China's recent growth occurred in industrial production, especially of goods for export. In the past few years, China's policies have attempted to shift from emphasizing heavy industry (such as steel) and production for export to stimulating domestic consumption and meeting domestic demands for improved quality of life. China has reduced its incentives for export-oriented production and increased incentives for investments in higher value-added goods and services. These policies, combined with increasing economic integration in Southeast Asia, could decrease the share of heavy manufacturing in China's economy, although preliminary data from early 2011 show that heavy manufacturing remains strong. Historically, China's promotion of monetary economic growth has led to severe environmental degradation. Many Chinese policymakers appear now to realize, however, that they cannot sustain an "unbalanced" approach that emphasizes industrialization at any cost, especially not in the developed regions of the country. Environmental pollution has become so bad in places that social and political stability are at risk. Officially recognized "public order disturbances" grew from 58,000 in 2003 to 87,000 in 2005, many due to environmental pollution and land-takings stemming from government corruption. Chinese officials have indicated that they seek a "harmonious society" that would entail slower GDP growth with less environmental degradation. In 2007, the World Bank, working with the Chinese government, estimated that the cost of outdoor air and water pollution to China's economy totaled around US$100 billion annually, or 5.8% of China's GDP. In other words, if non-monetized losses to China's resource assets (e.g., clean water, etc.) were netted from the current (financial) accounts, GDP would have been 5.8% lower. Related to such findings, the Chinese government raised the stated priority of environmental protection in its 11 th Five Year Plan (2006-2010). Chinese central government officials have over the past decade pursued a combination of measures to control air, water, and soil pollution, and state that they are striving to build a "recycling" industrialized economy to ease environmental pressures. Their efforts have met with mixed success. Even when national officials genuinely want to encourage environmental improvement, local officials may seek to avoid enforcement of environmental regulations (and may not report accurate data) in order to maximize industrial growth and employment.