Arctic Sea Ice Thinning Faster Than Previously Thought

It's no surprise that Arctic sea ice is thinning, however, a new study shows that the rate at which it's disappearing is much faster and steadier than scientists previously thought.

The results, published in the journal The Cryosphere, show that ice in the central Arctic Ocean thinned a stunning 65 percent between 1975 and 2012 - that's a drop from 11.7 feet (3.59 meters) to 4.1 feet (1.25 m).

What's more, the thinning is even steeper for September sea-ice levels, when sea ice is at its lowest after the summer melt. During the same 37-year stretch, ice cover was 85 percent thinner.

"The ice is thinning dramatically," lead researcher Ron Lindsay, a climatologist at the University of Washington (UW) Applied Physics Laboratory, said in a statement. "We knew the ice was thinning, but we now have additional confirmation on how fast, and we can see that it's not slowing down."

If climate change does not slow down and global temperatures continue to rise, it's likely that Arctic sea ice will completely disappear by the end of the century.

The study not only reveals the Arctic's dramatic changes over the last few decades, but may also help researchers better predict when the Arctic Ocean will be ice-free during parts of the year.

The problem with previous estimates of thinning sea ice in the Arctic was that the data was compiled into many different formats and scattered across several databases. And though this time around researchers acquired their data from a number of sources, they are the first to combine all available observations on Arctic sea-ice thickness into one study. For instance, from 1975 to 1990, most ice-thickness readings were from under-ice submarines. And since 2000, measurements are largely based on airborne and satellite measurements - such as NASA's IceSat satellite and IceBridge aircraft.

According to submarine data from 1975 to 2000, the Arctic sea ice thinned 36 percent - that's nearly half of what the new study found.

"This confirms and extends that study," Lindsay said.

Since the end of the study, which took observations up to the year 2012, Arctic ice has reached a record low, shrinking to its sixth-lowest level since satellite tracking started in 1979.

"Using all these different observations that have been collected over time, it pretty much verifies the trend that we have from the model for the past 13 years, though our estimate of thinning compared to previous decades may have been a little slow," co-researcher Axel Schweiger added.

All of the data in the study are now in the Unified Sea Ice Thickness Climate Data Record, which gets as many as 50,000 new measurements a month. The record is curated by UW researchers and stored at the US National Snow and Ice Data Center.

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