Study: Glacier that contributes most to rising sea levels reaches tipping point

By Catholic Online (NEWS CONSORTIUM)
1/17/2014 (4 years ago)
Catholic Online (https://www.catholic.org)

It's an alarming bit of news that raises concern for the world's ecology over the course of the next several decades. The Pine Island Glacier, which contributes more to sea level rise than any other glacier on Antarctica has hit a tipping point of uncontrollable retreat. The massive land mass could collapse as soon as the next 20 years, scientists say.

LOS ANGELES, CA (Catholic Online) - The glacier accounts for about 20 percent of the total ice flow on the West Antarctic Ice Sheet, which is a collection of glaciers that covers roughly 800,000 square miles. The landmass makes up about 10 percent of the total ice on Antarctica.

Researchers think that, given the size of Pine Island Glacier, its collapse could have an overall "domino effect" on surrounding glaciers. Over the course of many years would eventually lead to the collapse of the entire ice sheet, which would raise average global sea level by between 10 and 16 feet.

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The Pine Island Glacier is by far the least stable of the West Antarctic Ice Sheet ice flows. The glacier's melting rate has accelerated due to relatively warm ocean currents that have seeped underneath its base and lubricated its flow seaward.

As the glacier slip further into the ocean, its ice shelf, the part that floats on water and extends beyond the glacier's base, disintegrates through a natural process called calving. An iceberg larger than the city of Chicago broke off into the surrounding Amundsen Sea last year.

Given the complicated nature of glacial dynamics, attempts to map out the disintegration have been limited and prone to error. Such variable such as precipitation, wind patterns, atmospheric temperatures, oceanic currents and the shape of bedrock underneath the glacier are only some of the many factors that control glacial growth and retreat.

Models predicting glacial behavior using mathematical figures are therefore very complicated and always prone to some degree of error.

Researchers based at the French National Center for Scientific Research in Grenoble have now developed state-of-the-art models that, while still limited, provide the best estimates yet of the future behavior of Pine Island Glacier. The glacier's grounding line, the point where glacier and its ice shelf meet is about to retreat over an oceanic trench that would increase the amount of water that seeps underneath and melts the glacier.

The researcher's findings suggest that this would cause the glacier to uncontrollably retreat about 25 miles over the next several decades, potentially raising global sea levels by more than 0.4 inches.

Once glacier passes the trench, it will not likely regain stability or enter a positive-growth phase.

"Whatever it will do, we are already engaged in a big change," study co-author Gael Durand says. "We have passed the tipping point."

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