This article was solicited for the ACP 20th Anniversary collection. It received positive reviews that very nicely contributed to the ideas and to which the authors responded thoroughly. It is a stimulating read, combining 'big-picture' considerations with more detailed technical discussion of important and illuminating examples.

We very much welcome this useful opinion on ways to strengthen atmospheric research in the Global South.

The article is an interesting and provocative paper that derives its ideas from recently published research results and discoveries about the ambivalent role of atmospheric halogens (chlorine) in controlling the global abundance of tropospheric O3, OH and CH4. It discusses and proposes a possible roadmap to explore how artificially released iron chloride aerosols could reduce the atmospheric CH4 burden to mitigate its climate impact. The authors call for interdisciplinary efforts while keeping in mind ethical concerns and social impacts due to the proposed method.

The acquisition and proliferation of large datasets presents one of the greatest opportunities in environmental science in recent years, particularly with the application of open data principles in dissemination. However, the effective utilisation of these data poses new, ever greater technical and organisational challenges. This article discusses the methods and benefits of the application of the European ENVRI infrastructure to atmospheric science in programmes such as ACTRIS, IAGOS and ICOS, in particular through the application of FAIR principles, and how this will help to push back the frontiers of atmospheric science.