Despite a slowing global economy, carbon dioxide emissions continued to rise in 2007, according to energy use figures from oil company BP—jumping to 8.47 billion metric tons of the most common greenhouse gas responsible for global warming or 2.9 percent higher than the last year's total. Leading the charge: the U.S. (up nearly 2 percent to 1.58 billion metric tons) and China (up more than 7 percent to 1.8 billion metric tons).

These figures outpace even the worst-case projections of the U.N. Intergovernmental Panel on Climate Change, which warned last year that unless pollution is reduced, global average temperatures could rise by between four and 11 degrees Fahrenheit (two to six degrees Celsius).

Such a temperature rise would likely cause a slew of ill effects, among them: major melting of  ice sheets the world over (raising sea levels and impacting water supplies, particularly in Asia) and changes in weather patterns.
Developing countries currently account for more than half of global carbon dioxide emissions—led by China and India.

But that statistic is tempered by the fact that somewhere between one-quarter and one-third of Chinese emissions are the result of manufacturing for developed countries. On the other hand, Chinese emissions may be underestimated by as much as 20 percent by this study, according to author Gregg Marland, a scientist at Oak Ridge National Laboratory.

Emissions have been rising four times faster this decade, despite efforts such as the international Kyoto Protocol agreement to limit greenhouse gas pollution. Atmospheric concentrations of CO2 now stand at 383 parts-per-million (ppm), more than two ppm more than in 2006—a rate of growth matched throughout the 2000s and nearly double the rate of growth in the 1970s.

In addition to the rise in CO2 levels from fossil fuel burning, 1.5 billion metric tons of CO2 were added to the atmosphere by the cutting down of forests, according to the Global Carbon Project, the Australian group that analyzed the country data.

"The acceleration of both CO2 emissions and atmospheric accumulation are unprecedented and most astonishing during a decade of intense international developments to address climate change," said Pep Canadell, executive director of the Global Carbon Project.