BRUSSELS, Belgium (AP) -- Major polluters involved in the European Union's cap-and-trade program released slightly more carbon dioxide last year than in 2006, the European Commission said Friday.
But EU officials insisted that emissions would have been higher if Europe did not make power stations and steel plants trade carbon permits that load excessive polluters with extra costs.
They said the 0.68 percent increase in actual CO2 emissions from businesses that trade carbon permits was below economic growth of 2.8 percent for the 27-nation bloc last year.
The EU's top environment official, Stavros Dimas, said the carbon trading program was helping to curb emissions of the greenhouse gases blamed for rising global temperatures.
''Emissions trading is yielding results,'' he said. ''Studies show that emissions would most likely have been significantly higher without the EU emissions trading scheme.''
Carbon trading is in the heart of the European Union's push to cut carbon dioxide emissions by a fifth by 2020, a move it acknowledges will burden the economy with costs -- although it says these will be easier to bear than the full impact of climate change.
The 11,186 plants in the trading plan released 2.26 billion tons (2.05 billion metric tons) of CO2 last year.
Dimas said stricter limits were needed in future for the total amount of CO2 that can be released by large polluters. The EU has aimed to do that for the second phase of the trading plan that started this year and runs until the end of 2012.
Under the EU's carbon trading program, businesses receive permits that allow them to emit a fixed amount of carbon dioxide when they burn coal, oil and natural gas to power furnaces and electricity generators.
If they need to pollute more, they must buy extra permits from cleaner companies that release less. This creates an incentive for industry to invest in low-carbon technology and become more energy-efficient.
However, the first three years of the program have been widely criticized for setting the ceiling for CO2 emissions far above real pollution levels. These loose limits did not force polluters to make major changes.
Germany, the EU's largest economy and biggest source of CO2, saw its businesses release 1.8 percent more emissions last year than in 2006 as more companies joined in -- but this is still well below the annual allocation set for 2005 to 2007.
Still, the EU is ahead of the United States on this issue.
U.S. President George W. Bush has opposed mandatory emission cuts, but all three presidential contenders are supporters of a cap-and-trade system to reduce climate changing pollution, mainly carbon dioxide from the burning of fossil fuels.