The rise of new ozone-damaging gases

Short lived gases - previously thought to have little effect on the environment - can contribute to ozone depletion and influence climate.

A team of researchers at Leeds’ University School of Earth and Environment used a 3D computer model of the atmosphere and determined that very short-lived substances (VSLS) can have a damaging effect on ozone and affect climate.

The leader of the research Dr Ryan Hossaini 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.”

Naturally-emitted VSLS, such as gases produced from seaweed, account for 90% of the total ozone loss in the lower stratosphere. Over the last two decades, measurements of VSLS reveal a rapid increase in atmospheric concentrations in man-made VSLS used in a range of industrial processes such as dichloromethane. The contribution of dichloromethane is expected to increase further in coming years.

“At present, the long-term recovery of the Ozone Layer from the effects of chlorofluorocarbons (CFCs) is still on track, but the presence of increasing dichloromethane will lead to uncertainty in our future predictions of ozone and climate,” said Professor Martyn Chipperfield at Leeds’ School of Earth and Environment.

The study, published in Nature Geoscience, also revealed that the ozone depletion triggered by VSLS in the atmosphere today is small compared to that caused by longer-lived gases, such as CFCs. However short lived gases were found to have almost four times more influence on climate.

These substances have short atmospheric lifetimes, they break down and destroy ozone molecules in the lowermost part of the stratosphere. This has far larger impact on climate change than molecules damaged at higher altitudes by longer-lived gases.

“We need to continue monitoring the atmospheric abundance of these short-lived gases and determine their sources,” said Professor Chipperfield.

Paper: http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo2363.html