Can Closing the Ozone Hole Also Help Combat Climate Change?

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http://www.scientificamerican.com/article.cfm?id=can-closing-the-ozone-hole-also-combat-climate-change

November 5, 2009

Can Closing the Ozone Hole Also Help Combat Climate Change?

Finding alternatives to refrigerants such as hydrofluorocarbons will help prevent the ozone hole being healed at climate's expense

By Robynne Boyd

Carbon dioxide is the primary greenhouse culprit in http://www.scientificamerican.com/article.cfm?id=even-skeptics-admin-global-warming-is-real-video">human-generated global warming, most scientists agree, but CO2 itself, and a handful of other substances, are now being promoted as good alternatives to commonly used refrigerants that threaten Earth's atmosphere and climate.

To understand this paradoxical turn of events, it helps to recall the 1980s, when the world's governments banded together to fix the Antarctic http://www.scientificamerican.com/article.cfm?id=experts-ozone-hole-in-atmosphere-not-on-ground">ozone hole, a continent-size gap in the atmospheric layer that protects human beings, among other living things, from the sun's damaging ultraviolet radiation. Via the international treaty that entered into force in 1989 known as the Montreal Protocol, participants agreed to phase out the chemicals that harmed ozone. Closing the hole became one of the globe's greatest and most successful environmental restoration projects. But today, there is a glitch: The touted solution for the ozone predicament could in fact exacerbate our greatest environmental challenge—climate change.

The problem is that under the Montreal Protocol, which the U.S. has signed, hydrofluorocarbons (HFCs) were promoted as the environmental alternative to ozone-depleting hydrochlorofluorocarbons (HCFCs), which had become the standard working coolant in refrigerators, air conditioners and aerosol cans. HCFCs, for their part, originally replaced the even more potent ozone-depleting chlorofluorocarbons (CFCs) that were used liberally until the early 1990s. Whereas HFCs do not destroy the ozone layer, they can be thousands of times http://www.scientificamerican.com/article.cfm?id=a-mechanism-of-hot-air">more harmful to Earth's climate than carbon dioxide, posing a significant threat should they become HCFCs' main replacement.

"HCFCs and HFCs are two chemicals designed by chemists to trap heat; the fluorinated part of the compound turns what would be a normal hydrocarbon into something that is much more durable," explains Kert Davies, director of research for Greenpeace USA. "When you combine those two properties—heat trapping and durability—in the atmosphere, it creates a http://www.scientificamerican.com/article.cfm?id=from-bad-to-worse-with-greenhouse-gas-emissions">greenhouse gas. We created another problem by replacing the ozone depleters with chemicals that cause http://www.scientificamerican.com/topic.cfm?id=global-warming-and-climate-change">global warming, and now we need to replace these because they are going to be banned."

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