The scientists researched glacial melt dating back to 1851. Their observations showed that humans did not begin to affect glacial melt until about midway through the 20th century, when humans accounted for roughly 25% of melting glaciers. Not only have humans bore much more responsibility in the past couple of decades, but the overall rate of glacier melt has also rapidly increased. Each year during that time has seen 295 billion tons of ice melt as a result of human causes, as opposed to only 130 billion tons that have melted naturally.
Since the middle of the 19th century, an abundant number of glaciers have been melting. While scientists are unable to pinpoint the exact natural causes of the melt, the human reasons include soot, climate change (a result of burning oil, coal, and gas), and alterations in land use.
Although this study features an exceptional margin of error, the lowest possible percentage of melt caused by humans is still 45%, whereas the actual number could also be as high as 93%, a frightening prospect.