Establishing natural baselines of glacier variability in a warm world

The ongoing retreat of mountain glaciers worldwide is considered to represent a clear signal of anthropogenic global warming. In the Northern Hemisphere this attribution is strengthened by long (>100 yr) records of glacier and climate observations. However, Southern Hemisphere glaciers are less well studied, thus we must turn to the geological record to provide long-term context for understanding present and future change.

In New Zealand, existing geological records suggest that glaciers may have been larger than present for the majority of the Holocene Epoch (the last ~12,000 years). However, these records only represent times of past glacier advance, thus little is currently known about glacier response to previous periods of warming. Recent advances in geological dating techniques now provide the opportunity to address this knowledge gap, by directly quantifying the duration of past glacier retreat periods.

In our new research, we will utilise state-of-the-art dating techniques to determine how long New Zealand glaciers were smaller than today during the Holocene. Integrating these new geological constraints with computer model simulations of past glacier fluctuations, we aim to answer the question: Is the current retreat of New Zealand glaciers unprecedented in recent geological history?