Just when it seemed Earth’s protective ozone layer was healing, researchers have discovered that three types of ozone-depleting chemicals are rising again.
Soon after an international agreement took effect in 2004, levels of ozone-eating hydrochlorofluorocarbons, or HCFCs, began dropping in the atmosphere.
Since then, levels of the chemicals, found in car and home air conditioners, have been growing, according to the National Oceanic and Atmospheric Administration lab in Boulder.
“We thought everything was fine,” NOAA scientist Jim Elkins said. “This is very much a surprise.”
Near the Earth’s surface, ozone contributes to smog, but high in the stratosphere, the chemical forms a natural blanket that protects living things from damaging ultraviolet radiation.
Elkins and others blame the problem on another international environmental treaty – the Kyoto Protocol, designed to slow the emissions of greenhouse gases.
Under the protocol, when refrigeration companies in developing countries such as China and India make HCFCs, they are eligible for millions of dollars in U.N. credits when they burn off a byproduct that is a potent greenhouse gas.
Those companies could switch to a different refrigerant, but then they’d not produce waste gas or earn the credits, Elkins said.
This summer, the United Nations will consider a proposal from several countries, including the United States, to accelerate the phaseout of HCFCs.
Developing countries now are allowed to increase production of some HCFCs until 2016, according to the U.N.
The United States has already reduced its HCFC production by 35 percent since 1989, according to the federal Environmental Protection Agency, and has committed to stop producing and importing the chemicals by 2020.
Staff writer Katy Human can be reached at 303-954-1910 or khuman@denverpost.com.
This article has been corrected in this online archive. Originally, due to a reporting error it incorrectly reported the changing concentration of certain ozone-depleting chemicals in the atmosphere. Hydrochlorofluorocarbons were on the rise until about 2004, when an international treaty required developed countries to stop using and producing most of them.
