**Abstract**

The Antarctic Peninsula (AP) is a region of special climatological interest. The late twentieth century has been a period of warming surface temperatures, enhanced mass loss from melting glaciers and increased snowfall, which have a direct and measurable impact on global sea levels. However, the observational period for Antarctica is short. Observational records only began in the 1940s and much of our understanding of the wider spatial climate variability and glacial dynamics is limited to the satellite era (post 1979). Proxy records, such as those from ice cores, provide an invaluable tool to place these recent changes in context of the past few hundred years, allowing us to investigate climate variability over the entire twentieth century and beyond. In this chapter we review the climate of the AP during the twentieth century, as captured by the instrumental records, and extend our understanding of climate variability over the twentieth century based on climate proxies contained in ice cores. For this study we focus on stable water isotopes and snow accumulation and how they are influenced by changes in atmospheric circulation and sea ice conditions.

**Keywords:** Antarctic Peninsula, ice cores, climate, sea ice, surface mass balance
