Preliminary figures for 2005 show an average thinning of the ice on the majority of the world's glaciated mountain ranges of two-thirds of a meter (26 inches).
The data on glacier change for 2005 was collected from 80 glaciers by scientists all over the world and reported to the World Glacier Monitoring Service, WGMS, in Zurich.
Since 1980, scientists have recorded continuous measurements of overall ice thickness change on 30 of these glaciers in nine mountain ranges, so these are considered to be the reference glaciers.
The scientists report that since 1980 the average thickness loss of the 30 reference glaciers amounts to about 10.56 meters (34 feet).
Michael Zemp, a glaciologist and research associate at the World Glacier Monitoring Service said, 'Today, the glacier surface is much smaller than in the 1980s, this means that the climatic forcing has continued since then.'
By altering the global energy balance, changes in the composition of the Earth's atmosphere force the climate to change, so scientists call them climate forcing mechanisms.
Human activities over the past 250 years have emitted carbon dioxide and other greenhouse gases into the atmosphere, where they trap solar radiation close to the planet, raising the global temperature.
'The recent increase in rates of ice loss over reducing glacier surface areas leaves no doubt about the accelerated change in climatic conditions,' said Zemp.
The long-term monitoring of glacier mass produces one of the most essential variables required for the regular assessment reports on global climate monitoring.
The average annual ice loss for the reference glaciers since the year 2000 was about two-thirds of meter each year.
This amount of ice loss is 1.6 times more than the average of the 1990s and three times the loss rate of the 1980s.
Comprehensive data for the year 2006 are not yet available, but as it was one of the warmest years in many parts of the world, it is expected that the downward trend in ice mass will continue.
UNEP Executive Director Achim Steiner called the report 'the most authorative, comprehensive and up-to-date information on glaciers worldwide.'
'The findings confirm the science of human-induced climate change, confirmation that will be further underlined when the Intergovernmental Panel on Climate Change unveil their next report on February 2,' Steiner said.
These findings should strengthen the resolve of governments to act now to reduce greenhouse gas emissions and put in place the medium to longer term strategies necessary to avert dangerous climate change,' he said.
The new preliminary findings also underlines the importance of this year's June 5 World Environment Day theme, Melting Ice - A Hot Topic. The main international celebrations, which coincide with International Polar Year, will be held in Norway.
Worldwide collection of information about ongoing glacier changes was initiated in 1894 with the foundation of the International Glacier Commission at the 6th International Geological Congress in Zurich, Switzerland. Then, scientists hoped that long-term glacier observations would give insight into processes of climatic change such as the formation of ice ages.
Today, the World Glacier Monitoring Service collects standardized observations on changes in mass, volume, area and length of glaciers with time (glacier fluctuations), as well as statistical information on the distribution of perennial surface ice in space (glacier inventories).
Such glacier fluctuation and inventory data are high priority key variables in climate system monitoring. The most information is found for the Alps and Scandinavia, where long and uninterrupted records are available.