Thursday, May 15, 2014

Is Antarctic Ice Melt an Irreversible Disaster or Just More False Hype?

News media around the world have been all abuzz, with headlines declaring “Irreversible collapse of Antarctic glaciers has begun” and “West Antarctic Ice Sheet collapse is under way.” The “rapid” collapse threatens to cause sea level change of 4 to 13 feet. Calamity will surely follow. “Collapse will change the coastline of the whole world” shrieked the UK's Guardian, always a good source for mindless rumor mongering. What they are referring to are a pair of new reports that say the West Antarctic Ice Sheet (WAIS) has pushed its way over a submerged ridge that had been impeding its forward progress, causing the ice sheet to become unstuck from the sea floor. The WAIS is now flowing more freely, and hence more rapidly, into the sea. What the alarmist headlines don't say is that any impacts from this change are centuries to millennia in the future.
The two studies, one by NASA and the other 

by researchers at the University of Washington, looked at the Western Antarctica Ice Sheet over different stretches of time. The NASA study focused on melting over the last 20 years, while the University of Washington used computer model to predict the future of the WAIS. At least one of the papers could be considered real science, the type that takes actual measurements. Regardless, both studies arrived at similar conclusions: The thinning and melting of the Antarctic ice sheet is underway and cannot be halted. But that is not the whole story.

In fact, the screaming headlines obscure most of the facts of the situation—truth sacrificed in the name of sensationalism. What is not clearly stated is that all glaciers, including the WAIS and those on Greenland, are constantly flowing down hill. The reason they flow is that they are constantly gaining mass from accumulated snowfall. Glaciers grow from the top and the added mass causes the ice to flow down hill. If they are in a coastal area they can flow into the sea where chunks break off forming icebergs. If the ice was on land, its addition to the ocean will cause sea level to rise.
“Western Antarctic ice sheet collapse has already begun, scientists warn. Two separate studies confirm loss of ice sheet is inevitable, and will cause up to 4m of additional sea-level rise,” trumpeted 

the Guardian. “Collapse will change the coastline of the whole world!”

The often loony Huffington Post was a bit more measured in its reporting

“Part Of West Antarctic Ice Sheet Starting Slow, Unstoppable Collapse, Studies Indicate,” their headline stated. They too, said that the “alarmed” scientists expected even more sea level rise than previously predicted. Granted, the language used by the researchers was a bit alarming to those not familiar with the terminology used by glaciologists and other students of ice.

“The system is in sort of a chain reaction that is unstoppable,” said NASA glaciologist Eric Rignot, chief author of the NASA study in the journal Geophysical Research Letters. “Every process in this reaction is feeding the next one.”

“There's been a lot of speculation about the stability of marine ice sheets, and many scientists suspected that this kind of behavior is underway,” said Ian Joughin, a glaciologist at the University of Washington's Applied Physics Laboratory (APL) and the first author on the computer model paper. “This study provides a more quantitative idea of the rates at which the [ice sheet] collapse could take place.”

What they are most afraid of is that the grounding line, the boundary where a glacier touches the sea floor, could retreat, allowing warm water to undermine the ice and accelerate its melting. The NASA video below gives an idea of what the boffins are on about.
Bear in mind that rapid to scientists studying glaciers means something different from what rapid means to the average person. And while the word “collapse” implies a sudden change, the fastest scenario envisioned by the researchers is 200 years, and the longest is more than 1,000 years. Moreover, there are large uncertainties in these predictions because glaciers do not flow at consistent rates. Greenland's glaciers have recently demonstrated the variable nature of their march to the sea. The new “rapid” rate measures after the grounding line breakout in Antarctica will undoubtedly slow in the future. This leads to the question how fast is the ice shrinking in Antarctica? There are many different estimates.

Read the Rest HERE

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