Climate trends at Macquarie Island and expectations of future climate change in the sub-Antarctic

Macquarie Island has experienced a marked shift in its climate since 1970, with increasing precipitation, accompanied by a steady increase in mean wind speed associated with increased cyclonic activity. These trends are consistent with an increase in the Southern Annular Mode (SAM) index, albeit with a shift to an anomalous atmospheric trough over the western Pacific Ocean. However, our understanding of the twentieth-century climate across the entire sub-Arnarctic is limited by very sparse data and the relatively poor quality of global re-analyses across the Southern Hemisphere. Chapter 10 of the Inter-governmental Panel on Climate Change (IPCC) fourth Assessment Report (AR4) provides an assessment of global atmospheric trends out to the end of the twenty-first century and provides some clues as to the regional trends expected across the sub-Antarctic. This paper provides a synopsis of the changes experienced at Macquarie Island, and a look to future trends, and the need for increased atmospheric research in the mid- to high latitudes of the Southern Hemisphere.