The tasks of the WGMS are (l) to continue collecting and publishing standardized data on glacier fluctuations at 5-yearly intervals (2) to complete and continuously upgrade an inventory of the worlds glaciers (3) to publish results of mass balance measurements from selected reference glaciers at 2-yearly intervals (4) to include satellite observations of remote glaciers in order to reach global coverage and (5) to periodically assess ongoing changes. This work is being carried out at the Geographical Institute of the University of Zurich in collaboration with the Glaciology Section at the Laboratories of Hydraulics Hydrology and Glaciology (VAW) of ETH Zurich under the auspices of the International Commission on Snow and Ice (ICSI/IAHS) the Global Environment Monitoring System (GEMS/UNEP) the Federation of Astronomical and Geophysical Data Analysis Services (FAGS/ICSU) and the Division of Water Sciences of UNESCO. Data from WGMS flow into the World Data Center (WDC-A) for Glaciology (Boulder/Colorado) and the Global Resources Information Database (GRID) of GEMS (Geneva/Switzerland).
Collection of standardized glacier fluctuation data follows recommendations published by UNESCO in 1969 and regularly updated instructions for submission of data for the publication series Fluctuations of Glaciers (Vol. I 1959-65; Vol. II 1965-70; Vol. III 1970-75; Vol. IV 1975-80; Vol. V 1980-85; Vol. VI 1985-90). The third and fourth volume of this series saw a major step towards computer-based processing of data and in the last two volumes efforts were made to internationally collect and publish short abstracts on special events such as glacier surges ice avalanches glacier floods or debris flows drastic retreats of tidal glaciers and glacier-volcano interactions.
The 1989 published World Glacier Inventory - Status 1988 is a guide to the existing statistical data base on the world-wide distribution and morphological characteristics of glaciers as documented in regional inventories (some detailed others preliminary). Publication of the biennial Glacier Mass Balance Bulletin has now been started (No. 1 1988-89; No. 2 1990-91 No. 3 1992-93) and systematic remote sensing of glaciers in regions of difficult access is being planned. In addition a strategy is being developed on how to correctly interpret and periodically assess ongoing changes. The goal is to build up a modern service of global glacier monitoring with the measured information being stored in a data base system enabling easy access to scientific users.
One century of systematic observations clearly reveal a general shrinkage of mountain glaciers on a global scale. This general shrinkage remains one of the most reliable pieces of evidence for a worldwide secular warming trend. At a secular time scale the observed melt rates indicate energy fluxes which roughly correspond to the estimated anthropogenic greenhouse forcing. The trend was however most pronounced during the first half of the 20th century. After about 1950 glaciers started to grow again in several regions especially on the maritime slopes of mountain ranges where they are most sensitive to increased precipitation and where they gain mass despite rising air temperature. Since the 1980s the general shrinking tendency of mountain glaciers has been accelerating again. At least in the Alps glacier shrinkage now seems to be passing at a high and possibly accelerating rate beyond the range of preindustrial variability.