Roughly one-quarter of the global glacier mass loss between the years 1851 and 2010 can be attributed tohuman activities, and that fraction increased to more than two-thirds between 1991 and 2010, according to research published in the journal Science. The study is the first to document the extent of human contribution to glacier mass loss, which is driven by both naturally caused climate factors, such as fluctuations in solar radiation, and anthropogenic influences. “In the 19th and first half of 20th century we observed that glacier mass loss attributable to human activity is hardly noticeable but since then has steadily increased,” the lead researcher said. The analysis was based on data from the recently established Randolph Glacier Inventory and included all glaciers outside of Antarctica. Changes in glaciers in the Alps and North America were particularly well documented and seem to be definitively influenced by human activities, the researchers said.