WASHINGTON (Reuters) - The United States, Canada, and Mexico have proposed to amend a landmark global pact protecting the ozone layer to fight emissions of a refrigerant chemical thousands of times more potent a greenhouse gas than carbon dioxide, the U.S. EPA said on Thursday.
The proposal would expand the Montreal Protocol to phase down emissions of hydroflourocarbons, also known as HFCs, which are up to 14,000 times more damaging to the planet's climate system than carbon dioxide, the U.S. Environmental Protection Agency said.
"Reducing HFCs would help slow climate change and curb potential public health impacts," the EPA said in a release.
The EPA estimated that reductions in the proposal would be equivalent to removing greenhouse gas emissions from 59 million passenger cars each year through 2020 and 420 million cars each year through 2050.
The proposal would have to be approved and ratified by the Montreal Protocol members. Those that ratify the pact would be required to reduce emissions.
An environmentalist said it would be a victory in helping the fight against climate change.
"It would be an important contribution if HFCs were limited, but certainly carbon dioxide emissions remain the biggest problem," said Steve Seidel, a policy analyst at the Pew Center on Global Climate Change.
Late last year the EPA declared that greenhouse gas emissions endanger human health and welfare and the agency is taking other steps to reduce emissions of greenhouse gases from cars, power plants and factories as the climate bill stalls in the U.S. Congress.
The world is struggling to hammer out a replacement for the Kyoto Protocol on global warming that would aim to slash carbon dioxide emissions.
Nearly 200 countries in 1987 signed the Montreal Protocol, which is regarded by many to be one of the most successful global environmental treaties. The protocol helped restore the ozone layer, which shields life from the sun's harmful rays, by ending the production of chemicals such as chlorofluorocarbons (CFCs).
During the phaseout, however, manufacturers of equipment such as car air conditioners and kitchen refrigerators substituted HFCs before it was known that those chemicals were potent greenhouse gases.
On Thursday the EPA proposed four refrigerants as possible substitutes in U.S. refrigerators to replace existing refrigerants without harming the ozone layer or the climate system. The proposal lists isobutane, propane, HCR-188C and HCR-188C1 as acceptable substitutes.