Behaviour of New Zealand glaciers and atmospheric circulation changes over the past 130 years

There is renewed interest as to the impact of future climate change on temperate alpine glaciers because of their role as indicators of past and ongoing changes, and due to their possible involvement in sea-level rise. Substantial changes in termini of New Zealand glaciers since the nineteenth century are compared with variations in atmospheric circulation patterns over the southwest Pacific region. Reconstructed sea-level pressure patterns are used back to 1911. Atmospheric circulation indices obtained from pressure differences between appropriate stations are extended back to the 1860s. Circulation anomalies are examined for winter (related to glacier accumulation), and for summer (related to glacier ablation). Behaviour of glacier termini is found to be strongly linked with circulation changes, especially in summer. Latitudinal shifts in the southern margin of the subtropical high pressure zone are identified as important. An advance of some glaciers since 1980 is consistent with circulation changes over the New Zealand region induced by two large El Niño events.