Indirect methods of reducing greenhouse gas emissions through carbon trade and climate-friendly projects are growing in popularity, an international conference said on May 2.

The global carbon market tripled in 2006 to USD 30 billion from USD 10 billion in 2005, according to a World Bank study released at the annual Carbon Expo in Cologne.

Deutsche-Presse-Agentur (dpa) quoted United Nations climate chief Yvo de Boer as saying the global carbon market, which includes the trade in CO2 emissions, is a key element in the fight to halt climate change.

Despite the booming market in carbon trading, the worldwide volume in carbon emissions had not decreased, said De Boer, who heads the UN Climate Change secretariat.

De Boer spoke of confusion between official UN programmes to curb greenhouse gas emissions and largely unregulated private offset plans - such as planting trees - that are promoted on the global market.

The official UN scheme or Clean Development Mechanism is designed to help countries having difficulties meeting targets they signed up to under the Kyoto Protocol, which runs out in 2012.

The mechanism involves certified projects which help industrialised nations reduce their own emissions by investing in environmentally friendly projects in poor nations.

Some 650 such projects have been introduced in 44 countries, said the UN official, who warned that CO2 emissions could increase 60 percent in the next 25 years if no action is taken.

The World Bank report said the projects-based market in developing countries and countries with economies in transition had more than doubled to USD five billion in the 12 months to the end of 2006.

Since 2002, some USD eight billion has flowed from rich industrial countries to developing nations under the Kyoto Protocol-based clean development mechanism.

Some 220 companies from more than 60 countries took part in Carbon Expo, which specialises in international emissions trading.

Meanwhile, the United Nations on April 30 urged governments to devise long-term energy policies that can help sustain economic and social development as global energy use is expected to increase by 50 percent in the next 25 years,

The UN Sustainable Development Commission, which is meeting at UN headquarters in New York through May 11, said while energy issues dominate headlines, the world still has 2.4 billion people who depend on traditional firewood or dung for cooking or heat. "We will never achieve sustainable development goals as long as a third of all people do not have modern energy services," said Qatari Minister of Energy Abdullak Hamad al-Attiyah, who chairs the commission.