1st MAY, 2009.

The United States could ask the 195 signatories to the treaty on the protection of the ozone layer to reduce the use of hydrofluorocarbons (HFCs), a gas substitute for chlorofluorocarbons (CFCs) that contribute to climate change, according to officials American and documents obtained by The Associated Press.

The administration of Barack Obama has the intention to ask the countries that have ratified the treaty, known as the "Montreal Protocol", to implement mandatory reductions. "We believe that this is an option," said Adora Andy Wednesday, spokesman for the U.S. Agency for Environmental Protection (EPA). No decision has been taken yet, but this track is favored by the administration, she added.

This would be the first time that the United States propose to achieve a binding global gas emissions (GHG). Such an initiative would make the Montreal Protocol on protecting the ozone layer a major instrument in the fight against climate change.

The protocol, which dates back to 1988, virtually created the whole market for HFCs. The goal of the administration would be to include these gases in the treaty to restrict its use.

It is unclear how the device related to the Kyoto Protocol on reducing greenhouse gas emissions, which currently regulates HFCs but was rejected by the administration of George W. Bush. A new international treaty must be concluded in Copenhagen in December to replace the Kyoto agreement, which expires in 2012.

The Montreal Protocol is widely regarded as one of the treaties on the environment the most effective so far, it has eliminated CFCs, who are blamed for the reduction of the ozone layer over Antarctica.

HFCs, which are not harmful to the ozone layer, have replaced CFCs, including refrigerators, air conditioners, fire extinguishers, spray, medical devices and semiconductors.

They nevertheless pose problems for the climate, the experts stress. The United States regarded them as "a growing source of emissions and important" that could be removed more quickly by changing the Montreal Protocol or by creating "a separate but related to the treaty, said a document of the Department of State of March 27 presented at a recent conference.

Officials of the State Department told the conference last month that the United States wanted to amend the Montreal Protocol to phase out the use of HFCs, a measure hailed by environmental advocates.

But this option is still reluctant to within the U.S. administration, according to sources close to the case. And it is unclear whether the U.S. proposal on HFCs will be presented next week in time for consideration at a meeting in November of the parties to the Montreal Protocol.

Proponents of the measure argue that HFCs produce most of their adverse effects during the first 30 years in the atmosphere, unlike carbon dioxide, the impact of which extends over a longer period.

"Remove the HFC is our best hope" not to arrive soon at a point of no return on climate change, said Alexander von Bismarck, director of the Environmental Investigation Agency, an environmental organization that had launched the idea two years ago. "This is an opportunity that the world can not afford to miss."

The promotion of HFCs under the Montreal Protocol has resulted in a huge global market. Billions of dollars have been spent to encourage countries to abandon CFCs and other ozone-depleting substances for the benefit of inexpensive chemical agents such as hydrofluorocarbons.

According to scientists, the elimination of HFCs to save the planet a quantity of greenhouse gases up to a third of all CO2 emissions by 20 to 40 years. Manufacturers in Europe and the United States have begun to substitute other substances.

HFCs may have an effect on global warming up to 10,000 times greater than carbon dioxide, according to data from the U.S. government. They currently account for only 2% of all GHG emissions, but the Intergovernmental Panel on Climate Change (IPCC) warned in 2005 that their use increased by 8.8% per year.

More recent studies show that HFC emissions could reach 11 billion tonnes and up to one third of all greenhouse gas emissions by 2030-2040, according to some scenarios.

The EPA recently estimated that HFCs and five other greenhouse gases represent a danger to human health and the environment, a decision which could pave the way for mandatory reductions in the United States under the "Clean Air Act".