New Ozone-Destroying Gases Are on the Rise and Aren't Being Controlled

Ozone-destroying gases may be on the rise. Scientists have reported that chemicals that are not controlled by the United Nations treated designed to protect the Ozone Layer are contributing to ozone depletion.

In this case, the problem is very short-lived substances (VSLS). Measurements of VSLS in the atmosphere over the past two decades reveal a rapid increase in atmospheric concentrations of dichloromethane, a man-made VSLS used in a range of industrial processes. And while the amount of ozone depletion arising from VSLS in the atmosphere today is small compared to that caused by longer-lived gases, VSLS-driven ozone depletion is actually almost four times more efficient at influencing climate.

"We need to continue monitoring the atmospheric abundance of these gases and determine their source," said Martyn Chipperfield, one of the researchers, in a news release. "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."

VSLS break down and destroy ozone in the lowermost part of the stratosphere. This is importance since a molecule of ozone lost in this region has a far larger impact on climate than a molecule destroyed at higher altitudes.

Currently, naturally-emitted VSLS account for about 90 percent of the total ozone loss caused by VSLS in the lower stratosphere. However, the contribution from man-made VSLS compounds is increasing and appears set to increase further in coming years.

"The increases observed for dichloromethane are striking and unexpected; concentrations had been decreasing slowly in the late 1990s, but since then have increased by about a factor of two at sites throughout the globe," said Stephen Montzka, co-author of the new study.

The findings reveal that it's crucial to monitor VSLS in the future. The scientists are uncertain what's driving the growth of these ozone-depleting gases. However, it could be partly due to the face that dichloromethane is used in the manufacturing process of some HFCs.

The findings are published in the journal Nature Geoscience.

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