From: University of Leeds
Published February 17, 2015 08:07 AM

New ozone-destroying gases on the rise

Scientists report that chemicals that are not controlled by a United Nations treaty designed to protect the Ozone Layer are contributing to ozone depletion.

In the new study, published today in Nature Geoscience, the scientists also report the atmospheric abundance of one of these ‘very short-lived substances’ (VSLS) is growing rapidly.

Study lead author Dr Ryan Hossaini, from the School of Earth and Environment at the University of Leeds, said: “VSLS can have both natural and industrial sources. Industrial production of VSLS is not controlled by the United Nations Montreal Protocol because historically these chemicals have contributed little to ozone depletion.

“But we have identified now that one of these chemicals is increasing rapidly and, if this increase is allowed to continue, it could offset some of the benefits to the Ozone Layer provided by the Montreal Protocol.”

In the study, the researchers used a 3D computer model of the atmosphere to determine the impact of VSLS on ozone and climate.

Measurements of VSLS in the atmosphere over the past two decades, provided by collaborators from the National Oceanic and Atmospheric Administration (NOAA) in the United States, were also analysed. These measurements revealed a rapid increase in atmospheric concentrations of dichloromethane, a man-made VSLS used in a range of industrial processes. 

Study co-author Professor Martyn Chipperfield, from Leeds’ School of Earth and Environment, said: “We need to continue monitoring the atmospheric abundance of these gases and determine their sources. At present, the long-term recovery of the Ozone Layer from the effects of CFCs is still on track, but the presence of increasing dichloromethane will lead to uncertainty in our future predictions of ozone and climate.”

The researchers found that while the amount of ozone depletion arising from VSLS in the atmosphere today is small compared to that caused by longer-lived gases, such as CFCs, VSLS-driven ozone depletion was found to be almost four times more efficient at influencing climate.

Dr Hossaini explained: “Due to their short atmospheric lifetimes, VSLS break down and destroy ozone in the lowermost part of the stratosphere. This is important, as a molecule of ozone lost in this region has a far larger impact on climate than a molecule destroyed at higher altitudes by longer-lived gases.”

The researchers also separated out natural sources of VSLS – such as seaweed in the ocean – and those released due to human activity – such as industrial processes – in order to determine the relative importance of each.

Continue reading at the University of Leeds.

Air pollution image via Shutterstock.

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