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CO2 May Fragment Glaciers, Driving Ice Into the Sea Faster

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Scientists expect sea level to go up by 3 feet or so by the end of this century, thanks mostly to changes in the great ice sheets that dominate Greenland and Antarctica — but they worry about unknown factors that might drive ice into the sea faster than projected. Now a pair of MIT scientists has identified what might, in theory, turn out to be one of these “unknown unknowns.”

In a study released Wednesday in the Journal of Physics D: Applied Physics, Zhao Qin and Markus Buehler show that carbon dioxide, the main cause of global warming, can make ice more fragile and prone to cracking. This could mean, in principle anyway, that the extra CO2 pumped into the atmosphere by the burning of fossil fuels could make glaciers fragment more easily, and not just melt more quickly. And that could accelerate sea level rise, endangering people and property around the world.

A view of the Greenland ice sheet from space. 
Credit: NASA

The fragmentation is still largely theoretical, Buehler explained in an interview. “We look at tiny crystals of ice. Glaciers are much, much larger, so our research might or might not be relevant at that scale. We’re not addressing climate change in this paper,” Buehler said.

Climate change was, however, part of the inspiration for the research. Buehler and Zhao have studied the phenomenon of fracturing in materials ranging from metal to ceramic to spider silk. In many of these, fractures happen when some impurity shatters the hydrogen bonds that give the material its strength.

Hydrogen bonds also hold ice crystals together, and Zhao -- noting that huge chunks of glacier occasionally break off in both Antarctica and Greenland -- suggested they look at ice as well. “We realized,” Buehler said, “that this might be relevant to geoscientists who want to understand how these pieces behave.”

They didn’t use actual ice, but instead relied on a computer simulation to see what happened when a crack in a virtual ice crystal is invaded by molecules of carbon dioxide. Many materials naturally have microscopic cracks, and when impurities lodge there — salt molecules in concrete, CO2 molecules in ice — they can break the hydrogen bonds that hold things together. That’s what happened to the ice in the scientists’ simulations. “We created an ice crystal and put in some CO2,” Buehler said. The tiny crack spread and widened.

Buehler reiterated that this may or may not happen to a glacier-size chunk of ice in the real world. “The levels of CO2 we used in the simulation are much higher than the concentrations in the atmosphere,” he said. Buehler’s work also doesn’t address the question of how CO2 molecules would get into the ice; in a simulation, you just put the molecules where you want them.

But in the simulation, at least, you don’t need much CO2 to get things going. “Even just a single molecule,” Buehler said, “can lead to the nucleation [that is, the start] of a fracture.”

“I hope that this might lead to more studies of ice fracturing,” he said. “It might be interesting to look at.”

Given the potential significance of the new research for the future of planet, "might be interesting" is pretty clearly an understatement.

Related Coverage
Greenland Shed Two Manhattans’ Worth of Ice
Image of the Day: A Crack Across the Pine Island Glacier
The Story Behind Record Ice Loss in Greenland
Huge Chunk of a Greenland Glacier Set to Break Off – Again . . .

Comments

By Dillweed
on October 10th, 2012

I believe in Global Warming, but WOW. Just WOW.

“The fragmentation is still largely theoretical, Buehler explained…” 

We looked at tiny ice crystals… but we didn’t use actual ice. We used computuer simulations.

And the results may not be applicable because glaciers are much bigger than ice crystals.

Buehler reiterated that this may or may not happen to a glacier-size chunk of ice in the real world.

I’m not a journalist, but I would be embarrassed to have written this article. Let alone the title which should read.

Based on Simulations of Ice Crystal Glaciers May or May Not Slide Faster into the Ocean.

Reply to this comment

By Dave (Basking Ridge, NJ 07920)
on October 11th, 2012

I agree with Dillweed.

For instance, physicists are only just beginning to be able to measure directly how many water molecules it takes to make up an ice crystal. The structure of water, ice and ice processes are research areas. If you want to include this type of material here then it needs to be put into the correct context without titles that could mislead a lay audience. It gives the impression of undisciplined journalism.

Reply to this comment

By Jack Burton
on October 11th, 2012

I’ve no problem with this type of research into glacial ice and what the future may hold for it. But really, the earth is warming, the temperatures in glacial regions is warming, this melts the ice. We know this just by measurements from year to year. To me HOW glacial ice melts is really of small interest to a few scientists who are moved by the different processes that occur during glacial melting. But really, in the big picture that matters, all we care about is that temps are rising the ice is melting and nothing appears to be going to change this.
If there is a process by which it will melt a little faster or a little slower it still is headed in one direction. I just get a little irked by so much focus on process minutia when ice melts when it gets warm is what counts.

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By AnthonyBrown
on October 15th, 2012

Most of the studies are reporting that historic Arctic, Antarctic and Greenland ice are melting fast because of global warming. These studies also warn that they may not exist in future and it will effect humans hugely. I’ve found some amazing info about this here - http://www.rosebudmag.com/truth-squad/greenland-ice-melt-global-warning-largest-us-cities

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