Human Activity is Melting the World's Glaciers as Ice Retreats

As our world warms, glaciers continue to retreat. Now, though, researchers have found that this retreat can mostly be blamed on human contribution rather than natural climate fluctuations.

Glacier extent actually responds very slowly to climate changes. In fact, it typically takes glaciers decades or centuries to adjust to climate changes. 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. Until now, though, scientists haven't thoroughly examined the extent of human contribution to glacier mass loss.

In order to find that out, the researchers turned to computer simulations of the climate from 1851 to 2010. They included all glaciers in the world outside of Antarctica, using the recently establish Randolph Glacier Inventory (RGI). The researchers included different factors contributing to climate change in the model so that they could differentiate between natural and anthropogenic influences on glacier mass loss.

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

In fact, about a quarter of the global glacier mass loss between 1851 to 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," said Marzeion.

The findings reveal that human causes are contributing more and more to glacier loss over time. This highlights the fact that steps need to be taken in order to curtail these human impacts on climate.