New research by NASA found that a compound from an unknown source is destroying the ozone layer.
The compound — carbon tetrachloride — has been banned globally, and NASA doesn't know where it's coming from. Carbon tetrachloride used to be found in fire extinguishers and dry-cleaning products, but it was phased out under the Montreal Protocol in 1987.
NASA found that 39 kilotons of carbon tetrachloride were emitted over the last year, which is 30 percent of the peak emissions that occurred before the treaty went into effect. Zero emissions were reported from 2007 to 2012, so the findings are alarming.
"We are not supposed to be seeing this at all," Qing Liang, an atmospheric scientist at NASA's Goddard Space Flight Center and lead author of the study, said in a statement. "It is now apparent there are either unidentified industrial leakages, large emissions from contaminated sites, or unknown CCl4 sources."
The study also found that carbon tetrachloride can linger in the atmosphere longer than scientists previously thought. NASA's research was published in Monday's issue of Geophysical Research Letters. For more on how carbon tetrachloride is wrecking the ozone, check out the NASA video below. --Meghan DeMaria