Total traded volume in the global market reached 2.7 billion tonnes of greenhouse emissions reductions in 2007, a 64 percent jump in the same period.

The UN's climate panel last year squarely blamed human actions for global warming.

Carbon trade allows companies that have cut emissions under a set limit to sell credits representing the reductions to slower-moving players. It is seen as a major way to spur clean technologies that are hoped to slow and then decrease global emissions.

The United States, the world's largest greenhouse gas polluter, has not yet regulated the gases scientists blame for warming the planet. But 10 states on the East Coast plan to start trading carbon dioxide emissions credits from power plants next year, while states in the West and Midwest also plan to trade in regional markets.

Banks, hedge funds and exchanges in the United States, including the New York Mercantile Exchange, last year became increasingly involved in voluntary trading and preparation for possible national carbon regulations.

"This indicates a growing confidence that GHG emission trading will soon take off in the US, whether it is at the state or federal level," Point Carbon said in a statement.

Nearly two-thirds of the global trading volume last year occurred on the European Union's emissions trading scheme, with 1.6 billion tonnes of greenhouse emissions changing hands worth US$41 billion. The EU ETS, which kicked off in 2005, covers more than 10,000 power stations and other stationary sources of greenhouse gas pollution.

The other major market was the UN's Clean Development Mechanism, under which 947 million tonnes of greenhouse emissions were traded, worth US$17.5 billion, despite complaints that red tape has delayed projects.

The CDM allows players in rich countries to meet their emissions limits by investing in clean projects in developing countries, such as wind farms and hydroelectric projects, which otherwise would not have happened.

The secondary market in issued CDM credits rose from 40 million tonnes and US$836.2 million in 2006, to 350 million tonnes and US$8.3 billion in 2007, Point Carbon said.