Glaciers around the world are melting and retreating at a rate faster than anything ever recorded before, researchers at the World Glacier Monitoring Service at the University of Zurich in Switzerland say.

An analysis of data collected from more than 30 countries shows glaciers melted two to three times as fast in the first decade of this century than they did on average for the entire 20th century, they say.

"The observed glaciers currently lose between half a meter and one meter of ice thickness every year," says Michael Zemp, the director of the monitoring service.

That's the greatest rate of loss since record-keeping was initiated more than 120 years ago, the researchers report in the Journal of Glaciology.

To determine the rate of historical melt, they looked at satellite images and aerial and ground photos in addition to studying lithographs and drawings done in the 19th century and earlier.

The current rate of loss, equivalent of "about three times the ice volume stored in the entirety of the European Alps every year," is doubly as fast as what occurred in the '90s and three times faster than what occurred in the '80s, Zemp says.

While some glaciers in parts of the world have advanced rather than retreated, they are a small subset of the globe's ice rivers, and their advance doesn't begin to come closed to recovering the loss of the last 120 years, the researchers say.

While the study was based on exact measurements of ice loss from a few hundred glaciers, fieldwork and satellite observations confirm similar losses at tens of thousands of glaciers around the world, they say.

Driven largely by climate change and global warming, the glacial retreat is likely to continue in the future even if temperatures cease to rise and remain stable, Zemp emphasizes.

The study follows research published in March that found that glaciers in Antarctica are melting faster than scientists had believed, which could lead to rises in global sea levels greater than had been anticipated.

Some scientists are predicting a rise of close to 10 feet in the next half-century.

The latest study is a case of "bad news getting worse," Zemp says.

It should be on the minds of world leaders as they come together in Paris in a few months for the United Nations Conference on Climate Change, he suggests.

"We're getting used to the message that glaciers are melting," he says. "But we should not get too used to it."