Here's the good news: A hole in the ozone layer over the South Pole, which allowed dangerous levels of ultraviolet rays to reach Earth, has been shrinking since chemicals that destroyed atmospheric ozone molecules were banned in the 1990s.
But there's a downside. The chemicals that replaced those banned substances in aerosol cans and appliances like air conditioners and refrigerators are potent heat-trapping greenhouse gases. They're building up in the atmosphere at an increasing rate and exacerbating the warming caused primarily by fossil fuel emissions.
New research published Monday in the Proceedings of the National Academy of Sciences suggests that levels of one of those gases are far higher than what's publicly reported and that the levels go up sharply in the summer, when more air conditioners are running.
"It seems like common sense, but nobody has quantified or verified it before," Bin Xiang, an environmental chemist at Harvard University and lead author of the study, told VICE News.
Air samples taken from high-flying aircraft and at ground stations found concentrations of HFC-134a, commonly used in automobile air conditioners, were 60 percent higher than what was reported by industrialized nations.
Xiang told VICE News that some of the increase may come from leaking appliances and automobile air conditioners in developed countries but much of the rest is believed to be coming from developing countries that are using more refrigeration.
The chemicals tracked by Xiang and her team are less potent greenhouse gases than the old chemicals that damaged the ozone layer. In fact, getting rid of the old chemicals — known as chlorofluorocarbons, or CFCs — has done more to prevent dangerous temperature rise than any other international effort, David Fahey, Senior Scientist for Climate at the National Oceanic and Atmospheric Administration's Earth Systems Research Laboratory, told VICE News.
"It was somewhat inadvertent," he said. "They were after ozone protection at the time."
CFCs were banned by the Montreal Protocol, which took effect in 1989. They were replaced by chemicals known as hyrdrochlorofluorocarbons (HCFCs), which did far less harm to the ozone layer, and hydrofluorocarbons (HFCs), which don't damage ozone at all.
The substitutes are released in far smaller amounts than carbon dioxide, the most common human-generatedgreenhouse compound. But they're 1,000-2,000 times more potent than carbon dioxide, and scientists estimate they account for two percent of observed warming of Earth's climate, Xiang told VICE News.
Under the Montreal Protocol, HCFCs are to be phased out by 2020 in the industrialized nations and by 2030 in developing ones. But there's no international agreement for phasing out HFCs, and the US Environmental Protection Agency estimates they could account for 19 percent of the nation's greenhouse gas emissions by 2050 if left unchecked.
'We do need to tackle this problem so we can get through this century without doing any more harm to ourselves.'
The United Nations estimates that getting rid of CFCs was the equivalent of reducing carbon dioxide emissions by more than 11 billion metric tons a year; phasing out HCFCs could add another 12-16 billion tons to that figure by 2050.
Fahey spoke to VICE News from Paris, where he was attending a conference of scientists, engineers, and industry representatives from countries that have signed the Montreal Protocol. Figuring out how to phase out HFCs next was one of the items up for discussion in Paris, he said.
"There have been a number of years in a row now where the parties have tried to come to an agreement about how to go forward and whether to go forward with HFCs," Fahey said. "They haven't agreed yet, and it's not clear what will happen."
The Group of 20 leading economic powers have agreed to reduce them as substitutes become available, and several countries have made plans to curtail them on their own.
The United States, Canada, and Mexico laid out a proposal in May to reduce HFC use by more than 80 percent by 2050. The United States has also begun talks with India and China, the two largest developing economies, and those two countries reportedly reached an agreement to address the issue at last week's Paris conference.
Some substances may be more environmentally friendly but might not work as well in hot climates. Companies like DuPont are working on new synthetic compounds for air conditioners and industrial coolants. Organic compounds like ammonia, one of the original refrigerants, are widely used for industrial cooling but pose health risks if they leak.
The refrigeration industry says leaks during servicing and installation are the biggest source of HFC emissions. But Xiang said hotter weather means higher pressures inside cooling systems, causing more severe leaks. And more people driving means more potential accidents, which can damage air conditioning compressors and hoses. Motorists and auto repair professionals can reduce the number of leaks by following government procedures for handling and recovering coolants, she said.
"There are regulations about how to properly replace or dispose of the coolants from the air conditioner," she said. "Some drivers do it themselves, and doing the procedure can leak some of the coolants in the air. Some garages don't pay much attention to these procedures. I did want to bring their attention to a better way."
Brenda Ekwurzel, senior climate scientist at the Union of Concerned Scientists, said HFCs should rank just below fossil fuels as a target for climate negotiators.
"Ironically, climate change will create more of a need for refrigerants, so we do need to tackle this problem so we can get through this century without doing any more harm to ourselves," Ekwurzel told VICE News.
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