Chlorofluorocarbons and. Ozone Depletion atoms, and leads to the destruction of atmospheric ozone.” .. Public Affairs and Public Relations. ACS is a. What is the relationship between CFCs and ozone in the stratosphere Score 0 of from PCB at Florida Atlantic University. Approximately 90 percent of the atmosphere's ozone occurs from 10–18 km (6– 11 once freed by UV radiation from the chlorofluorocarbons (CFCs) and other.
Using a combination of measurements from satellites, ground-based instruments, and weather balloons, her team found that, sincethe September hole has shrunk by 4 million square kilometers—an area bigger than India. To determine whether declining pollutants deserve credit for the recovery, the researchers used a 3D atmospheric model to separate the effects of the chemicals from those of weather, which can affect ozone loss through winds and temperature, and volcanic eruptions, which deplete ozone by pumping sulfate particles into the upper atmosphere.
The sulfate can play the same role as cloud particles, activating chlorine. The model helped explain why scientists saw a record ozone hole in Octobera glaring exception to the shrinking trend. Solomon and some other researchers at first wondered whether the recovery might be behind schedule. But the model showed that it was a fluke due to the eruption of the Calbuco volcano in southern Chile 6 months earlier, and it confirmed that declining levels of chlorine and its chemical cousin bromine were indeed responsible for the longer term healing trend.
But those studies separated out the effects of natural variability using relatively simple statistical techniques, and many researchers questioned the assumptions that went into them. The other half appeared to be due to weather. Weather effects ought to cancel out on average, resulting in no trend, he says.
Ozone layer on the mend, thanks to chemical ban
Or, he says, it may reflect a real shift in polar weather, driven by climate change. Zaelke said he was surprised by the findings, not just because the chemical has long been banned, but also because alternatives already exist, making it hard to imagine what the market for CFC today would be. Their results were published in the journal Nature. There is a small chance that there is a more innocent explanation for the rise in CFC emissions, the scientist say.
Ozone layer on the mend, thanks to chemical ban | Science | AAAS
They considered a range of alternative explanations for the growth, such as a change in atmospheric patterns that gradually remove CFC gases in the stratosphere, an increase in the rate of demolition of buildings containing old residues of CFC, or accidental production. But they concluded these sources could not explain the increase, which they calculated at about 13 billion grams per year in recent years.
Rather, the evidence "strongly suggests" a new source of emissions, the scientists wrote. CFC, used primarily for foams and in refrigerators, can lasts up to 50 years in the atmosphere once it's released. It is only destroyed in the stratosphere, some 14 to 29 kilometres above the planet's surface, where the resulting chlorine molecules engage in a string of ozone-destroying chemical reactions.
That loss of ozone, in turn, weakens our protection from UV radiation at the Earth's surface. The chemical is also a powerful greenhouse gas that contributes to global warming. Loading "It is therefore imperative that this finding be discussed at the next ministerial meeting of governments given recovery of the ozone layer is dependent on all countries complying with the Montreal Protocol and its adjustments and amendments with emissions globally dropping to zero.
Keith Weller, a spokesman for the United Nations Environment Program, which administers the Montreal Protocol, said the findings will have to be verified by the scientific panel to the protocol, and then would be put before the treaty's member countries. But Zaelke thought the finding could promote tougher action.