EGU Twitter Journal Club: Article 4 — Ozone, nitrogen oxide emissions, and climate mitigation

It’s time for the fourth edition of the EGU’s Twitter Journal Club, our interactive online discussion about a timely scientific article. If you have not yet taken part in one of these discussions, read more about it in our introductory post and make sure to participate when we meet online next week! 

This time, we will be discussing a recent Open Access article from the journal Atmospheric Environment, covering the various approaches used to calculate contributions of individual nitrogen oxide emissions to creating ozone – and hence towards climate change.

The discussion will take place on Twitter next Thursday 25 October at 14:00 CEST, and you can take part by following the EGU’s Twitter account (@EuroGeosciences) and using the hashtag #egutjc4 on your tweets. Please email the EGU’s Science Communications Fellow Edvard Glücksman if you have any further questions.

Happy reading!

Nitrogen oxide emissions from burning fossil fuels are important contributors to the formation of ozone, and hence to climate change. (Source: Wikimedia)


Attributing ozone to NOx emissions: Implications for climate mitigation measures

Atmospheric Environment 59 (2012) 102-107

Abstract. Emissions of nitrogen oxides (NOx) lead to formation of ozone, which is an important greenhouse gas. Despite its relevance, little emphasis was previously given on verifying approaches to calculate contributions of individual emissions to ozone and hence to climate change. Basically two methods (perturbation method and tagging method) were used in the past. We demonstrate that both methods are valid and have their area of application, but only tagging calculates contributions of emissions to concentrations, whereas the perturbation method identifies changes in the ozone concentrations due to emission changes. Our results show that the contribution of road traffic emissions to climate change is underestimated by a factor of 5 in the perturbation method. This is caused by non-linear compensating effects from other emission sectors, which are concealed in the perturbation method but disclosed with tagging. Consequently, the effectiveness of mitigation measures for individual sectors (i.e. concentrating on road traffic induced ozone) is only correctly expressed by the tagging method. The perturbation method provides accurately the total impact (i.e. total ozone) of a mitigation measure. However, current approaches, which evaluate the effectiveness of a mitigation measure based on the perturbation approach, do not reflect changes in the chemical state of the atmosphere (i.e. ozone production rates). These largely affect the effectiveness of subsequent measures and hence make the evaluation of the effectiveness of two measures dependent on their chronology of application. We show that also in this regard, the tagging method is better suited to evaluate the effectiveness of a mitigation measure than the perturbation method.

Questions to think about:

1. How would you summarise this article in a tweet?

2. What are the broader implications of this study?

3. Which approach seems to be the most effective in calculating contributions of individual emissions to ozone?

4. What would be an interesting follow-up study to this work?


Bárbara Ferreira was the Media and Communications Manager of the European Geosciences Union from 2011 to 2019. Bárbara has also worked as a science writer specialising in astrophysics and space sciences, producing articles for the European Space Agency and others on a freelance basis. She has a PhD in astrophysics from the University of Cambridge.


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  4. Thanks for your comments, Sarah and Julia. Good points to consider!

  5. Planting trees to save the world.

  6. Very good article. Really enjoyed reading it. Just to note, perturbation methods have been really gaining popularity!


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