Humans to Blame for World's Melting Glaciers

As our world warms, glacial ice continues to retreat. However, scientists have now come to realize that humans are mostly to blame, rather than being able to solely peg it on natural climate fluctuations, according to a new study.

Glacier extent actually responds very slowly to climate changes. In fact, it typically takes glaciers decades or centuries to adjust. The global retreat of these massive chunks of ice started around the middle of the 19^th century at the end of the Little Ice Age. Though until now, scientists hadn't thoroughly examined the extent of human contribution to glacier mass loss.

To investigate further, researchers turned to computer simulations of the climate from 1851 to 2010. They included the entire world's glaciers, with the exception of those in Antarctica, using the recently establish Randolph Glacier Inventory (RGI). They also included different factors contributing to climate change in the model so that they could differentiate between natural and anthropogenic - or human-caused - influences on glacier mass loss.

"While we keep factors such as solar variability and volcanic eruptions unchanged, we are able to modify land use changes and greenhouse gas emissions in our models," Ben Marzeion from the University of Innsbruck, who led the study, said in a news release. "In our data we find unambiguous evidence of anthropogenic contribution to glacier mass loss."

In fact, about one quarter (25-35 percent) of the global glacier mass loss between 1851 and 2010 can be attributed to anthropogenic causes. This fraction increased further to two thirds between 1991 and 2010.

"In the 19^th and first half of the 20^th century we observed that glacier mass loss attributable to human activity is hardly noticeable but since then has steadily increased," Marzeion said.

The findings show that human activities are contributing more and more to glacier loss over time. This highlights the need for urgent action to try to limit human impact on our global climate.

The study's findings are described in further detail in the journal Science.