A market analysis company says the global trade in carbon emissions credits expanded last year, but falling prices meant roughly the same amount of money changed hands.

An analysis of the trade, which is concentrated in Europe, has significance for the United States and several other countries that are considering a cap-and-trade system to control greenhouse gas emissions.

Norway-based Point Carbon said 8.2 gigatons of carbon dioxide were bought and sold in 2009 for a total of euro94 billion ($135 billion). The volume of trade was 68 percent higher than in 2008, but its value was up just euro2 billion.

Analyst Endre Tvinnereim said Wednesday the global financial crisis caused a slowdown in industry and in carbon emissions, resulting in lower market prices.