(Paul Kuehnel/AP)

The Obama administration is preparing to introduce major steps to phase out production of a popular chemical coolant used in refrigerators and air conditioners, citing growing evidence that the substance is contributing to the warming of the planet.

The White House will announce on Tuesday a series of voluntary commitments by some of the country’s largest chemical firms and retailers to move rapidly away from R-134a and similar compounds used in nearly every office, home and automobile in the country, according to current and former U.S. officials familiar with the effort.

The administration is simultaneously stepping up diplomatic efforts to encourage major U.S. trading partners to phase out production of the potent greenhouse gas, the officials said. The initiatives are being disclosed in advance of next week’s summit of world leaders at the United Nations to debate options for slowing the buildup of heat-trapping gases in the atmosphere.

The class of chemicals to which R-134a belongs — called hydrofluorocarbons, or HFCs — became popular as a replacement for Freon, the refrigerant banned since the 1990s for damaging the Earth’s ozone layer. Most HFCs are harmless to ozone, but collectively they have become a significant driver of climate change — some are up to 10,000 times as potent per ounce as carbon dioxide, climate scientists say.

The steps unveiled this week are intended to accelerate the phaseout of most types of HFCs while still allowing manufacturers time to shift to more environmentally friendly replacements. If fully im­plemented, the measures would have an impact equivalent to removing 15 million cars from the nation’s highways for a decade, according to an administration official familiar with details of the plan.

Estimated global consumption of HFCs by various sectors, expressed in carbon dioxide equivalent, for 1990, 2002 and 2010. (TEAP/EPA/UNEP)

“These are some of the strongest greenhouse gases in the atmosphere,” said the official, who insisted on anonymity as discussions were underway to finalize the plans. The White House also was expected to announce several executive measures to expedite the shift to replacement chemicals.

The Obama administration has been seeking since 2010 to phase out production of HFCs, both through voluntary agreements as well as proposed new amendments to the Montreal Protocol, the treaty that outlawed Freon two decades ago. The initiatives to be announced Tuesday would expand the effort by securing the cooperation of a Who’s Who list of U.S. companies, ranging from major chemical manufacturers such as DuPont to some of the biggest users of refrigerants, such as Coca-Cola and PepsiCo and the retailers Target and Kroger.

Among the voluntary participants is a coalition of chemical manufacturers representing 95 percent of U.S. production of HFCs. The companies have agreed to rapidly introduce replacement coolants into the market while taking additional steps to prevent leaks of R-134a into the environment, the administration official said. Coca-Cola, meanwhile, is expected to announce a goal to purchase only HFC-free refrigerators and cooling systems throughout its global network. Several of the companies had already begun making the shift to alternative coolants, responding to new restrictions on HFCs in the European Union as well as economists’ predictions of an eventual ban in the United States. One leading alternative to R-134a — called HFO-1234YF — can be used in most existing cooling systems without significant modifications.

The new steps to be outlined this week would provide a significant boost to the administration’s efforts on climate change at a time when prospects for a global climate treaty appear uncertain at best. Despite increasingly dire warnings from scientists about the buildup of heat-trapping greenhouse gases in the atmosphere, Congress has long been hostile to any binding international treaty limiting U.S. carbon emissions.

Removing the potential threat from HFCs could eliminate a serious threat to the climate at a relatively small cost while buying time for countries to tackle the more difficult challenge of cutting carbon-dioxide emissions from fossil-fuel burning, said Durwood Zaelke, president of the Washington-based Institute for Governance and Sustainable Development and author of a prominent textbook on environmental law.

“If we don’t deal with the HFC problem now, in the future these gases are going to kill us,” Zaelke said. “Fortunately, there are already replacement technologies for most uses, and you can take steps now that are relatively small and cheap.”

Although the volume of HFCs in the atmosphere is relatively small, the EPA projects that concentrations of the gases will grow by nearly 140 percent by the end of the decade, compared with levels that existed in 2005.

Projected increase in radiative forcing of HFCs. The increase is significant when compared to the increase in radiative forcing from carbon dioxide since 2000. (Velders et al./UNEP)

The Obama administration last year secured an agreement with China to work jointly on reducing domestic emissions of HFCs, and the United States joined Mexico and Canada earlier this year in proposing an amendment to the Montreal Protocol phasing out production of R-134a and related compounds.

The White House also has been lobbying other manufacturers of HFCs in the developing world, particularly India, whose newly elected prime minister, Narendra Modi, is expected to visit Washington for official talks later this month. The Indian government in the past ruled out curbs on its domestic production of HFCs, saying it lacks an alternative. “We are saying we don’t have any alternative technology,” Sushil Kumar, a senior Indian environmental official, told reporters last fall.