The Earth’s ozone layer shields all life from the sun’s harmful radiation. However, human emissions of certain harmful chemicals began to affect the number of ozone molecules in the atmosphere in the late twentieth century. As a result of complex meteorological and chemical processes, a dramatic hole opens up over Antarctica every year.
Researchers have developed a new method for assessing the effects of ozone-depleting substances that threaten the ozone layer’s recovery. Their method, the Integrated Ozone Depletion (IOD) metric, was published in the journal Nature and is a useful tool for policymakers and scientists.
The IOD was created to provide a simple method for measuring the effects of unregulated ozone-depleting substance emissions and assessing the effectiveness of ozone layer protection measures.
The ozone layer is found in the stratosphere of the earth’s atmosphere and serves as an important protective barrier against the majority of the sun’s harmful ultraviolet rays. Ozone-depleting gases, such as chlorofluorocarbons, or CFCs, have been phased out under the Montreal Protocol, an international agreement to protect the ozone layer.
We developed the IOD metric using the UKCA model, which will allow us to estimate the impact of any new illegal or unregulated emissions on the ozone layer. We can run experiments in the UKCA model with various types and concentrations of CFCs and other ozone depleting substances.Dr Luke Abraham
The Montreal Protocol has been largely successful, but illegal breaches are jeopardizing its efficacy. The IOD indicates the impact of any new emissions on the ozone layer by considering three things: the strength of the emission, how long it will remain in the atmosphere, and how much ozone is chemically destroyed by it.
The IOD is a simple way to calculate the impact of any given emission scenario on ozone recovery for environmental and human health policies. This new metric was created by researchers at the University of Cambridge’s National Centre for Atmospheric Science and the University of Leeds’ National Centre for Earth Observation.
Professor John Pyle of the National Centre for Atmospheric Science and the University of Cambridge has dedicated his career to studying stratospheric ozone depletion and assisting in the development of the Montreal Protocol. He is the lead author of the most recent Nature paper.
“Following the Montreal Protocol, we are now in a new phase – assessing the recovery of the ozone layer,” said Pyle, from Cambridge’s Yusuf Hamied Department of Chemistry. “This new phase calls for new metrics, like the Integrated Ozone Depletion – which we refer to as the IOD. Our new metric can measure the impact of emissions – regardless of their size. Using an atmospheric chemistry computer model, we have been able to demonstrate a simple linear relationship between the IOD, the size of the emissions and the chemical lifetimes. So, with knowledge of the lifetimes, it is a simple matter to calculate the IOD, making this an excellent metric both for science and policy.”
The Montreal Protocol is successfully protecting the ozone layer, but there is mounting evidence that the ozone hole is recovering at a slower rate than expected. “The IOD will be very useful for monitoring ozone recovery, especially for regulators who need to phase out substances that have the potential to chemically destroy ozone,” Pyle said.
The IOD metric was developed using the UK Chemistry and Aerosols model, a computer model of the atmosphere (UKCA). The UKCA model was developed by the National Centre for Atmospheric Science and the Met Office to calculate future projections of important chemicals such as ozone in the stratosphere.
“We developed the IOD metric using the UKCA model, which will allow us to estimate the impact of any new illegal or unregulated emissions on the ozone layer. We can run experiments in the UKCA model with various types and concentrations of CFCs and other ozone-depleting substances” Dr. Luke Abraham, a co-author from the University of Cambridge, agreed. “We can forecast how chemicals in the atmosphere will change in the future and assess the ozone layer’s impact over the next century.”