China will be the "champion" of fighting climate change if it can reach the energy consumption targets it has already set, according to the chief economist of International Energy Agency (IEA).

Speaking at the U.S. Council on Foreign Relations think tank in New York Monday evening, Fatih Birol said the targets China set for itself to achieve by 2020 would contribute more than 25 percent of what needed to be done globally to reduce carbon emissions.

Though he is not sure if China will reach the targets, he trusts it "more than many governments and members" of the Organization for Economic Cooperation and Development (OECD).

Birol said he was "very hopeful" that China would reach its targets just as it had set and met targets for population growth, sustainable economic growth and bringing electricity to half of a billion people in rural areas.

Paris-based IEA is promoting a "low-carbon energy revolution" in order to slow the global temperature rise to 2-degree Celsius by 2030 from a 6-degree rise that would occur if there were no cut in the use of coal and petroleum.

Birol, director of the office responsible for economic analysis of energy policy at IEA, recently founded the IEA's Energy Business Council, which draws together leaders from the world's foremost energy corporations to provide a business perspective on a broad range of energy market challenges.

Birol demonstrated that, if global oil demands kept growing and output of existing fields continued to decline, the world would need to discover and produce some 45 million barrels of oil more a day by 2030 just to meet current demand of 85 million to 86 million barrels a day.

"That is four new Saudi Arabias," he said.

He believes natural gas can play a key role as a bridge to a cleaner energy future. At current demand levels, some 60 percent of the world's natural gas output would need to be replaced with new fields by 2030, a volume equal to four times the current output of Russia, the world's biggest gas producer, Birol said.

According to Birol, in the United States and European Union, average annual expenditure on net imports of oil and gas will double its share of gross domestic product from a current 1 percent by the year of 2030.

The global cost of the needed carbon reduction would be a huge 10.5 trillion U.S. dollars, but each year of delay would add 500 billion dollars to it, he said.

The IEA's approach to tackling climate change and enhancing energy security would lower OPEC earnings to nearly 24 trillion dollars in 2030 from 28 trillion during 2008, but Birol said OPEC would be willing to participate in the global cause.

"They are part of the solution," he said.