LOS ANGELES, CA (Catholic Online) - A peer-reviewed study puts to rest the debate over whether the poles added to, or subtracted from, sea level rise over the last 20 years.

"This improved certainty allows us to say definitively that both Antarctica and Greenland have been losing ice," lead author Andrew Shepherd of the University of Leeds in Britain told reporters. The data tells an especially terrifying tale: the pace has tripled from the nineties.

The study "shows that the Antarctic and Greenland ice sheets have contributed just over 11 millimeters (0.4 inches) to global sea levels since 1992," he says. Of that amount two-thirds was from Greenland, a third from Antarctica.

This 20-mile-long rift on Antarctica's Pine Island Glacier, seen from a satellite on Oct. 26, will eventually calve off, possibly in the next few months, creating an iceberg the size of New York City.

This event won't push sea levels higher since the glacial tongue sits on water. The loss, however could speed up the flow of ice from Antarctica's mainland into the sea.
In recent years, the percentage "has gone up significantly" to nearly 40 percent, added co-author Michiel van den Broeke from Utrecht University in the Netherlands.

As published in the journal Science, the study was based on input from 47 experts at the 26 institutes that produced earlier studies with wild variations. Some of those studies estimated melt was raising sea levels by up to two millimeters a year, while a few said that overall polar ice was growing, and thus countering sea level rise.

While Eastern Antarctica has indeed added ice, continent-wide the last decade shows a "50 percent increase in ice loss rate," study co-author Erik Ivins, a satellite data expert with NASA's Jet Propulsion Lab says.

Greenland's melt rate has gone from 55 billion tons a year in the 1990s to nearly 290 billion tons a year recently, according to the study.

A top ice expert who was not a study co-author told NBC News that the new data mark "an important step forward" in better estimating future sea level rise.

"While we had a basic picture of what was going on, it was an incomplete and blurry one," Mark Serreze, director of the National Snow and Ice Data Center at the University of Colorado-Boulder says. "We needed to step back and take a fresh look, making the best use of all of the different data sources that we have.

"With this study," he added, "we now have a lot confidence in how the ice sheets are behaving."

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