July 5, 2022

expert reaction to research claiming ozone hole over tropics

A study, published in AIP Advances, reports a hole in the ozone layer over the Tropics.

Dr Paul Young, Lancaster University and a lead author of the 2022 WMO/UNEP Scientific Assessment of Ozone Depletion, said:

“There is no ‘tropical ozone hole’, driven by the author’s proposed electrons from cosmic rays or otherwise. The long term changes and year-to-year variability of the ozone layer in the tropical lower stratosphere (~15-20 km up) are well understood to be the result of both human-driven processes and natural drivers. 

“Prior to ~2000, it was the increasing concentrations of chlorofluorocarbons (CFCs) that drove a decrease in ozone in this region, which have now been phased out by the Montreal Protocol. Since 2000, tropical stratospheric ozone levels have indeed still been decreasing, but this is due to changes in atmospheric motions expected with climate change. 

“The author’s identification of a ‘tropical ozone hole’ is down to him looking at percentage changes in ozone, rather than absolute changes, with the latter being much more relevant for damaging UV reaching the surface. Interestingly, his article also does not draw from the vast literature that explores and documents ozone trends in all regions of the atmosphere.”

Dr Marta Abalos Alvarez, Researcher in the department of Physics of the Earth and Astrophysics at the Complutense University of Madrid (UCM), said:

“In my opinion the article lacks the scientific rigour necessary to be a reliable contribution. It contains a lot of reasoning with serious errors and unsubstantiated assertions, contradicting previous results that are substantiated. Ozone depletion in the tropics is nothing new and is mainly due to the acceleration of the Brewer-Dobson circulation. Finally, the journal in which it is published has a very low impact factor.”

Prof Martyn Chipperfield, Professor of Atmospheric Chemistry, University of Leeds, said:

“I am surprised that this study was published at all in its current form.  The results of this work will be highly controversial and I’m not convinced they are correct.  We already have a good understanding of polar ozone depletion from different, well-established chemical mechanisms which can explain the slow and variable closing of the Antarctic Ozone Hole, and this new research doesn’t persuade me otherwise.  The claim in this research of such large ozone changes in the tropics have not been apparent in other studies which makes me very suspicious.  Science should never depend on just one study and this new work needs careful verification before it can be accepted as fact.”

‘Observation of Large and All-Season Ozone Losses over the Tropics’ by Qing-Bin Lu was published in AIP Advances at 4pm UK TIME on Tuesday 5 July 2022.

DOI: 10.1063/5.0094629 

Declared interests

Prof Chipperfield: ‘I am heavily involved in the WMO/UNEP Ozone Assessment (and other work) where we show that CFCs cause ozone depletion through well-established mechanisms.’

No others received.