Antarctica is ‘past the point of no return’

Last week the National Climate Assessment was released with the dire warning that “Climate change, once considered an issue for a distant future, has moved firmly into the present.” National Climate Assessment: climate change has moved firmly into the present.

On Monday, a University of Washington study warned that the Thwaites Glacier is “past the point of no return.” Antarctic glaciers said to be ‘past point of no return’:

IceSheetA slow-motion and irreversible collapse of a massive cluster of glaciers in Antarctica has begun, and could cause sea levels to rise across the planet by another 4 feet within 200 years, scientists concluded in two studies released Monday. (h/t NASA, AFP/Getty Images)

Researchers had previously estimated that the cluster in the Amundsen Sea region of the West Antarctic Ice Sheet would last for thousands of years despite global climate change. But the new studies found that the loss is underway now as warming ocean water melts away the base of the ice shelf, and is occurring far more rapidly than scientists expected.

The warming water is tied to several environmental phenomena, including a warming of the planet driven by emissions from human activity and depleted ozone that has changed wind patterns in the area, the studies found.

“There is no red button to stop this,” said Eric Rignot, a UC Irvine professor of Earth system science and the lead author of one of the studies, conducted with NASA’s Jet Propulsion Laboratory and scheduled for publication in a journal of the American Geophysical Union.

The six glaciers have passed “the point of no return,” Rignot said, which means that total collapse — the melted retreat of the glaciers — cannot be prevented. “The only question is how fast it’s going to go.”

Antarctica, surrounding the South Pole, is the largest mass of ice on the planet, containing an estimated 80% of the world’s fresh water. Its scale is difficult to fathom. One environmental foundation said that if you loaded the ice onto cargo ships and started counting the vessels, one per second, it would take 860 years before you were finished counting.

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For the UCI-JPL study, scientists used 40 years’ worth of measurements, much of it data from satellite radar systems that can measure changes on Earth’s surface to within a quarter of an inch.

The data was used to measure the precise location of the glaciers’ so-called grounding lines — the point at which glaciers connect to a land mass. It is at this nexus where warmer ocean water encounters the ancient ice and causes it to retreat.

The problem compounds itself in several ways, scientists said.

The more grounding lines recede, for instance, the less glaciers weigh, which lifts them farther off Earth’s bedrock, which allows even more warm water to erode their foundations. Similarly, as the glaciers retreat into deeper portions of the ocean, their ice faces become steeper, rendering them increasingly unstable and increasingly exposed to warmer water.

The second study, conducted by researchers at the University of Washington and scheduled for publication in the journal Science, focused largely on one of the six glaciers, the Thwaites Glacier. Scientists attempted to pinpoint how quickly the giant Thwaites might disappear altogether, a development that by itself could cause global sea levels to rise by 2 feet.

That amount of sea level rise would have a chaotic impact.

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The University of Washington study used satellite measurements and computer models to determine that the Thwaites could melt in as little as 200 years, or the melting could take as long as 1,000 years. Ian Joughin, a university glaciologist and the lead author of that study, said the most likely scenario is at the lower end of that range.

“There is quite a bit of ongoing destabilization,” he said, and the disappearance would begin slowly and accelerate over time, with no available “stabilizing mechanism.”

The Thwaites is an important test case because it is viewed as particularly unstable, and a linchpin for the stability of the rest of the West Antarctic Ice Sheet. As goes the Thwaites, many scientists fear, so goes the rest of the ice sheet — its disappearance would undermine the entire glacial system, exposing many more miles of grounding lines to the warming ocean water.

“You can’t just remove this glacier cleanly,” Joughin said. “You pull one part out, the rest will move into the void.”

If the entire ice sheet disappeared, the global sea level could rise by a catastrophic 15 feet.

“Eventually, this could lead to the demise of ice across Antarctica,” Rignot said.

The scientists were careful to point out that an inevitability is not cause for surrender. The 800-year range for the time frame is enormous, they pointed out — and was driven by computer models that “turned up the knob and turned down the knob” on global temperatures driven by climate change, Joughin said. More emissions mean more melting and faster collapse, the researchers said, but the inverse is true, too.

“Eight hundred years is a long time,” Joughin said.

A significant reduction in emissions and other safeguards against climate change could extend the collapse closer to the upper end of that range. Think of the technological advances in the last 800 years to gauge how much that time could help in safeguarding coastal areas from the impact of rising sea level, Joughin said.

Of course, the average American politician only asks “is it going to affect my race before November?” Because if not, it can wait. Good stewardship of the planet is not their concern.

UPDATE: John Oliver on his new HBO show Last Week Tonight demonstrates the correct way to have a climate science “debate.” “The debate on climate change should not be whether it exists, but what we should do about it.”

4 responses to “Antarctica is ‘past the point of no return’

  1. Thucky, tell that to the people who live on Long Island or in New Orleans.

  2. Thucydides

    Really? Really? Four feet in 200 years is 2 feet in 100 years is .2 ft in ten years is .02 feet next year is .24 inches next year is 1.64 centimeters.

    Over the last 20,000 years, the oceans have risen an average of 1.3 centimeters per year.

    Par for the course.

    • AZ BlueMeanie

      David Horsey of the LA Times: “Of all the ways the strident wackiness of the Republican Party is harming our country, the absolute worst is the obstinate, willfully ignorant refusal of GOP leaders to deal with the biggest existential threat facing the United States: climate change.” http://www.latimes.com/opinion/topoftheticket/la-na-tt-calamities-of-climate-change-20140507-story.html

    • The question here is whether you’re intellectually dishonest, or just a moron. Yes, sea levels are up from 20,000 years ago, but that’s measuring from the depth of the last ice age. Sea levels also have been essentially flat for the last 2,000 years. Do you not understand how unprecedented and disastrous it would be for sea levels to rise from levels at or near their historical peaks at a rate greater than the rate they have in the past only when recovering from their historical nadir?

      This is similar to your comment about the growth of the economy in the US since 1860, when the US population was 23 million. It hadn’t dawned on you that if the US population growth over the last 150 years repeated itself over the next 150, we’d have 4 billion people crammed onto the same land mass that now holds only 318 million.