The world pumped up emissions of the chief human-produced global warming gas last year, setting a course that could push beyond leading scientists' projected worst-case scenario, international researchers said Thursday.
The new numbers, which some scientists called "scary," were a surprise because experts thought an economic downturn would slow energy use. Instead, carbon dioxide output rose 3% from 2006 to 2007.
That amount exceeds the most dire outlook for emissions from burning coal and oil and related activities as projected by a Nobel Prize-winning group of international scientists in 2007.
Meanwhile, forests and oceans, which suck up carbon dioxide, are doing so at lower rates, scientists said. If those trends continue, the world will be on track for the highest predicted rises in temperature and sea level.
The U.N.'s Intergovernmental Panel on Climate Change has warned that an increase of between 3.2 and 9.7 degrees Fahrenheit could trigger massive environmental changes, including melting of the Greenland ice sheet, the Himalayan-Tibetan glaciers and summer sea ice in the Arctic.
Corinne Le Quere, professor of environmental sciences at the University of East Anglia and the British Antarctic Survey, said the prediction that current emissions put the planet on track for a temperature rise of more than 11 degrees means the world could face a dangerous rise in sea level as well as other drastic changes.
Richard Moss, vice president and managing director for climate change at the World Wildlife Fund, said the new carbon figures and research showed that "we're already locked into more warming than we thought."
"We should be worried -- really worried," Moss told the Washington Post. "This is happening in the context of trying to reduce emissions."
The new data also shows that forests and oceans, which naturally take up much of the carbon dioxide humans emit, are having less impact. These "natural sinks" have absorbed 54% of carbon dioxide emissions released since 2000, a drop of 3 percentage points compared with the period between 1959 and 2000.
The pollution leader was China, followed by the United States, which past data show is the leader in emissions per person in carbon dioxide output. And although several developed countries slightly reduced output in 2007, the U.S. churned out more.
Still, it was large increases from China, India and other developing countries that spurred the growth of carbon dioxide pollution to a record high of 9.34 billion tons of carbon. Figures released by science agencies in the U.S., Great Britain and Australia show that China's added emissions accounted for more than half of the worldwide increase. China passed the U.S. as the No. 1 carbon dioxide polluter in 2006.
Emissions in the U.S. rose nearly 2% in 2007, after declining the previous year. The U.S. produced 1.75 billion tons of carbon.
"Things are happening very, very fast," Le Quere told the Associated Press. "It's scary."
Gregg Marland, a senior staff scientist at the U.S. Department of Energy's Oak Ridge National Laboratory in Tennessee, said he was surprised at the results because he thought world emissions would drop because of the economic downturn. That didn't happen.
"If we're going to do something [about reducing emissions], it's got to be different than what we're doing," he said.
The emissions are based on data from oil giant BP PLC, which show that China has become the major driver of world trends. China emitted 2 billion tons of carbon last year, up 7.5% from the previous year.
"We're shipping jobs offshore from the U.S., but we're also shipping carbon dioxide emissions with them," Marland said. "China is making fertilizer and cement and steel, and all of those are heavy energy-intensive industries."
Developing countries not asked to reduce greenhouse gases by the 1997 Kyoto treaty -- China and India are among them -- now account for 53% of carbon dioxide pollution. That group of nations surpassed industrialized ones in carbon dioxide emissions in 2005, an analysis of older figures shows.
India is in position to beat Russia for the No. 3 carbon dioxide polluter behind the U.S., Marland said. Indonesia's levels are increasing rapidly.
Denmark's emissions dropped 8%. The United Kingdom and Germany reduced carbon dioxide pollution by 3%, while France and Australia cut it by 2%.
But it remains unclear how much industrialized countries will be able to reduce their carbon output in the years to come, regardless of whether developing nations seek to restrain their greenhouse gas emissions. The federal government predicts U.S. fossil fuel consumption will increase. Japan, Canada and several other countries that committed to reducing their carbon emissions under the 1997 Kyoto Protocol have fallen far behind in meeting their targets.
Moreover, new scientific research suggests the globe is already destined for a greater worldwide temperature rise than predicted. Last month, two scientists from the Scripps Institution of Oceanography and UC San Diego published research showing that even if humans stopped generating greenhouse gases immediately, the world's average temperature would "most likely" increase by 4.3 degrees Fahrenheit by the end of this century.
Writing in the journal Proceedings of the National Academies of Science, they based their calculations on the fact that new air-quality measures worldwide are reducing the amount of fine particles, or aerosols, in the atmosphere and diminishing their cooling effect.
What is "kind of scary" is that the worldwide emissions growth is beyond the highest growth in fossil fuel predicted just two years ago by the Intergovernmental Panel on Climate Change, said Benjamin Santer, an atmospheric scientist at the Lawrence Livermore National Laboratory.
Under the panel's scenario then, temperatures would increase by somewhere between 4 and 11 degrees Fahrenheit by 2100.
If this trend continues for the century, we would be exceedingly lucky "for it just to be bad, as opposed to catastrophic," said Stanford University climate scientist Stephen H. Schneider.