The application of glacier inventory data for estimating past climate change effects on mountain glaciers: A comparison between the European Alps and the Southern Alps of New Zealand

This study uses the database from national glacier inventories in the European Alps and the Southern Alps of New Zealand (hereinafter called the New Zealand Alps), which contain for the time of the mid-1970s a total of 5154 and 3132 perennial surface ice bodies, covering 2909 km2 and 1139 km2 respectively, and applies to the mid-1970s. Only 1763 (35%) for the European Alps and 702 (22%) for the New Zealand Alps, of these are ice bodies larger than 0.2 km2, covering 2533 km2 (88%) and 979 km2 (86%) of the total surface area, respectively containing useful information on surface area, total length, and maximum and minimum altitude. A parameterisation scheme using these four variables to estimate specific mean mass balance and glacier volumes in the mid-1970s and in the ‘1850 extent’ applied to the samples with surface areas greater than 0.2 km2, yielded a total volume of 126 km3 for the European Alps and 67 km3 for the Southern Alps of New Zealand. The calculated area change since the ‘1850 extent’ is − 49% for the New Zealand Alps and − 35% for the European Alps, with a corresponding volume loss of − 61% and − 48%, respectively. From cumulative measured length change data an average mass balance for the investigated period could be determined at − 0.33 m water equivalent (we) per year for the European Alps and − 1.25 m we for the ‘wet’ and − 0.54 m we per year for the ‘dry’ glaciers of the New Zealand Alps. However, there is some uncertainty in several unknown factors, such as the values used in the parameterisation scheme of mass balance gradients, which, in New Zealand vary between 5 and 25 mm m− 1.