This commentary paper from the recently formed International Global Atmospheric Chemistry (IGAC)
Southern Hemisphere Working Group outlines key issues in atmospheric composition research that
particularly impact the Southern Hemisphere. In this article, we present a broad overview of many of the
challenges for understanding atmospheric chemistry in the Southern Hemisphere, before focusing in on
the most significant factors that differentiate it from the Northern Hemisphere. We present sections on
the importance of biogenic emissions and fires in the Southern Hemisphere, showing that these emissions
often dominate over anthropogenic emissions in many regions.We then describe how these and other factors
influence air quality in different parts of the Southern Hemisphere. Finally, we describe the key role of the
Southern Ocean in influencing atmospheric chemistry and conclude with a description of the aims and scope
of the newly formed IGAC Southern Hemisphere Working Group.
