Your love for decaffeinated tea or coffee may have led to ozone depletion, say scientists who found that a chemical commonly used to in the food industry delayed recovery of the atmosphere's protective layer by up to 30 years.

Researchers from Lancaster University in the UK found that a previously ignored chemical called dichloromethane may now be contributing to ozone depletion and should be looked at to improve future ozone predictions.

Dichloromethane is a man-made ozone-depleting chemical that is used in the food industry, to decaffeinate coffee and tea as well as to prepare extracts of hops and other flavourings.

The projections by researchers show that continued dichloromethane increases at the average trend observed from 2004-2014 would delay ozone recovery over Antarctica by 30 years.

“Unlike chlorofluorocarbons and similar long-lived gases that are responsible for most ozone depletion, it has a short atmospheric lifetime so has not been controlled by the Montreal Protocol,” said Ryan Hossaini from Lancaster University.
“Despite this, increased production has led to a rapid increase in its atmospheric concentration over the past decade,” Hossaini added.

The projections by researchers show that continued dichloromethane increases at the average trend observed from 2004-2014 would delay ozone recovery over Antarctica by 30 years.

If dichloromethane concentrations stay at current levels, the delay in recovery would be only five years. Although the future trajectory of dichloromethane is uncertain, without any regulations on emissions, it is likely concentrations will fall somewhere in between the ranges presented here.

Researchers used simulations with a global chemical transport model to examine the sensitivity of future stratospheric chlorine and ozone levels to sustained dichloromethane growth.

Measurements of dichloromethane in the atmosphere over the past two decades, provided by scientists from the National Oceanic and Atmospheric Administration (NOAA) in the US, were also analysed.

The increases observed for dichloromethane from our measurements are striking and unexpected; concentrations had been decreasing slowly in the late 1990s, but since the early 2000s have increased by about a factor of two at sites throughout the globe, researchers said.

“It is uncertain what is driving this growth. However, it could be related to increased use of this chemical as a solvent in place of other long-lived chemicals (eg CFCs and HCFCs) that have been phased out, or from use as feedstock in the production of other chemicals,” they said.

The study was published in the the journal Nature Communications.