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The US Environmental Protection Agency announced a rule Monday that would phase out hydrofluorocarbons (HFCs), the potent greenhouse gases that are widely used as refrigerants.
Though HFCs aren’t intentionally emitted in the regular use of refrigerators and air conditioners, they often leak out at various phases in an appliance’s life cycle, from manufacturing through disposal. One of the most widely used HFCs, R-134a, causes 1,430 times more warming than an equivalent amount of carbon dioxide over 100 years. Another that is commonly used in supermarkets, R-404A, has a global warming potential of 3,900. Eliminating the use of HFCs worldwide would reduce emissions enough to avoid up to 0.5˚C (0.9˚F) of warming by 2100.
HFCs were first introduced in the mid-1990s as replacements for chlorofluorocarbons (CFCs), which were the previous standard for refrigerants. CFCs deplete the ozone layer that protects the Earth from harmful ultraviolet radiation, and decades of use led to a massive hole, discovered in 1974, in the atmosphere above Antarctica. As concern over the ozone hole grew, countries from around the world signed onto the Montreal Protocol, which called for the phaseout of CFCs and other ozone-depleting substances. Finalized in 1987 and ratified by the US Senate the following year, the treaty is widely seen as a success—as CFC use has dwindled, the ozone layer has begun to repair itself, and by 2040, experts believe the hole will begin to steadily close.
When HFCs were introduced, they were an appealing replacement for CFCs. They have shorter lifespans than CFCs and are less reactive with ozone. But as their use grew, so did concern over their potential as greenhouse gases. And the concerns are real—leaks in supermarket refrigerators and freezers are so widespread that the industry estimates supermarkets lose 25 percent of their refrigerant charge annually. Once again, countries from around the world came together to address the issue, signing the Kigali Amendment that updated the Montreal Protocol to include HFCs. Notably, neither the US nor China has ratified the agreement, but last month, the two largest greenhouse gas emitters both agreed to eliminate the use of HFCs.
In the US, the phaseout enjoys support from both major political parties, and there are already substitutes available for new refrigerators and air conditioners. One substitute that is already in many models of refrigerators is isobutane. Known in the industry as R-600a, it’s inexpensive, it has almost no ozone depletion potential, and it has a small global warming potential (three instead of R-134a's 1,430). Already, manufacturers have begun switching to the new refrigerant.
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