One source on this question is the Climate Analysis Indicators Tool from the World Resources Institute. It is a secondary compilation of statistics from other sources in a very accessible inquiry format. According to the CAIT, in 2000, the United States accounted for 6.6 billion metric tons of carbon dioxide emissions — 15.7% of the world total. We made the largest total contribution of any nation, 16th highest on a per capita basis. This statistic includes net impact of land use changes — deforestation and reforestation — and also includes carbon dioxide equivalents for other greenhouse gases, like methane.
On a straight carbon dioxide emission basis, the United States accounted for 24.0% of emissions, highest in the world, and was 5th highest per capita in 2000 (only exceeded by Qatar, the United Arab Emirates, Kuwait and Bahrain). In 2003, China ranked 2d in the world on total CO2 emissions, but 75th in the world in per capita emissions. U.S per capita emissions in 2003 were 19.9 tons of CO2 per person as compared to a world average of 4.1 tons per person. Click here for 2003 data by region or here for 2003 data by country.
For very close, but slightly different totals, see the United States Government’s Energy Information Administration’s carbon dioxide emissions data or the U.S. Environmental Protection Agency’s summary of emissions. China’s economy is growing fast, increasing carbon dioxide emissions from fossil fuel combustion by 55.3% from 2000 to 2004 according to the EIA, while the United States’ emissions grew only 1.7%. China’s total carbon emissions stood at 79.6% of the United States total level in 2004.