This project – which involves scientists from two dozen countries – will examine how atmospheric processes in the Southern Hemisphere affect current climate, and provide an important baseline for assessing future climate change. COMPASS will obtain the first circumpolar snapshot of the Southern Hemisphere atmospheric environment – covering physical, chemical and ecological properties – a major observational milestone. Only by harnessing the resources of the global polar community can this multinational project achieve the depth of investigation required to improve knowledge of future climate change and its impacts.