Antarctica's ice shelves are thinner than we thought. Here's what that means for sea levels

This January 2010 photo shows the area near the grounding line of the Pine Island Glacier along its west side in Antarctica. (Ian Joughin via AP)

New research has found that previous studies on the Antarctic ice shelves may have overestimated their thickness, an important factor for scientists to determine how fast sea levels could rise.

Researchers from Ohio State University say in a study published in the Journal of Glaciology last month that previous estimates were off by almost six per cent on average, amounting to a difference of about 17 metres.

The researchers say while this may seem small in scale, a typical ice shelf can range from 50 to 600 metres thick.

Previous research, at times, understated ice shelf thickness in some areas.

"Because the Antarctic ice sheet is so big, a one per cent misestimation in how fast it's melting could mean inches or feet of sea level rise that we're not accounting for," Allison Chartrand, lead author of the study and a doctoral graduate of the Byrd Polar and Climate Research Center, told Ohio State News on Friday.

"So it's really important to be as accurate as we can."

The researchers looked at "vast datasets" for 20 of Antarctica's 300 ice shelf systems, or floating tongues of ice that extend from glaciers on land.

The ice shelves surround about three-quarters of the Antarctic ice sheet, considered the largest block of ice on Earth covering more than 14 million square kilometres and measuring about two kilometres thick.

The researchers say while past estimates about the thickness of the Antarctic ice shelves were correct at a large scale, it varied much more on a small scale given how difficult it can be to try and accurately measure narrow valleys and crevasses.

Chartrand says ice shelves play a large role in stabilizing the Antarctic ice sheet and that a few inches of displaced ice shelf could cause thicker ice to flow into the ocean, resulting in several feet of loss to some coastlines.

The study states that more accurate data is needed to better predict ice shelf loss.

"What this research really shows is that we need to be a lot more careful about the assumptions we make to estimate the ice shelf thickness, and about how we account for uncertainties and what they mean for the final result," Chartrand said.