Location of large mystery source of banned ozone-depleting substance uncovered

The compound, carbon tetrachloride, contributes to the destruction of the Earth's ozone layer, which protects us from harmful ultraviolet radiation.

As a result, the production of carbon tetrachloride has been banned throughout the world since 2010 for uses that will result in its release to the atmosphere. The global emissions have not declined as expected, with about 40,000 tonnes still being emitted each year. Alongside collaborators from South Korea, Switzerland, Australia, and the USA, researchers at the University of Bristol aimed to quantify emissions from eastern Asia.

To do this, they used ground-based and airborne atmospheric concentration data from near the Korean peninsula and two models that simulate the transport of gases through the atmosphere. Around half of the 'missing' global emissions of carbon tetrachloride originated from eastern China between 2009 and 2016.

The phase-out of carbon tetrachloride production for emissive use in 2010, found no evidence for a subsequent decrease in emissions. The monitoring of man-made ozone-depleting gases in the atmosphere is essential to ensure the continued success of the phase-out of these compounds.