Internationally coordinated long-term glacier observations started in 1894 with the establishment of the International Glacier Commission at Zurich, Switzerland. The goal of this worldwide glacier monitoring programme was to provide answers to the fundamental questions about mechanisms of modern climate and glacier variations. Since 1894, the goals of internationally coordinated glacier monitoring have evolved and multiplied. Today, glacier signals are recognized as high-confidence temperature indicators and as a valuable element of early detection strategies in view of possible man-induced climate change (cf. the 1995 reports by the Intergovernmental Panel on Climate Change, IPCC).
Observed glacier fluctuations, indeed, contribute important information about ranges of natural variability and rates of change with respect to long-term energy fluxes at the earth's surface. Glacier fluctuations reconstructed for historical and Holocene time periods from direct measurements, old paintings, written sources or moraines indicate that glacier extent in many mountain regions may have varied over the past centuries and millennia within a range defined by the extremes of the maximum Little Ice Age advance and today's reduced stage, respectively. As indicated by spectacular losses in glacier length, the general shrinkage of mountain glaciers during the 20th century is a major reflection of the fact that rapid secular change in the energy balance of the earth's surface is taking place on a global scale. The characteristic rate of this change (a few decimeters ice depth per year) as deduced from glacier mass losses is broadly consistent with the estimated anthropogenic greenhouse forcing (a few W/m2). The beginning of this rapid secular glacier retreat tendency was probably little affected by human activity. The observed evolution may, however, contain an increasing part of anthropogenic influence: recent shrinking of glaciers for the first time now coincides with a man-induced radiative forcing which could be responsible for a major part of the additional energy flux causing the observed melt rate. The situation appears to evolve at a high rate towards or even beyond the "warm" limit of natural holocene variability. In this situation, directly measured glacier mass balances belong to the key indicators for assessing possible trends of continuation or acceleration.
As a contribution to the Global Environment Monitoring System (GEMS) of the United Nations Environment Programme (UNEP) and to the International Hydrological Programme (IHP) of the United Nations Educational, Scientific and Cultural Organisation (UNESCO), the World Glacier Monitoring Service (WGMS) of the International Commission on Snow and Ice (ICSI/IAHS), as one of the permanent services of the Federation of Astronomical, Geophysical and Data Analysis Services (FAGS/ICSU), collects and publishes standardized glacier data. The following series of reports on the variations of glaciers in space and time were already published by the World Glacier Monitoring Service and its predecessor, the Permanent Service on the Fluctuations of Glaciers:
The present Glacier Mass Balance Bulletin (MBB) reporting the results for the balance years 1993/94 and 1994/95 is the fourth issue of a long-term series of publications. It is designed to speed up and facilitate access to information concerning glacier mass balances by reporting measured values from selected reference glaciers at 2-year intervals. The results of glacier mass balance measurements are made more easily understandable for non-specialists through the use of graphic presentations rather than purely numerical data. The Glacier Mass Balance Bulletin complements the publication series, "Fluctuations of Glaciers", where the full collection of digital data, including the more numerous observations of glacier length variation, can be found. It should be kept in mind also that this fast and somewhat preliminary reporting of mass balance measurements may require slight corrections and updates at a later time. Corrected and updated information can be found in the Fluctuations series. It is planned to make the present Mass Balance Bulletin available on the Internet. As soon as this is realized it will be announced on the homepage of the WGMS: http://www.geo.unizh.ch/wgms/ The fifth Glacier Mass Balance Bulletin will cover the years 1995/96 and 1996/97. It will be prepared in 1998.
Zurich, December 1996