Submitted by Anonymous on Wed, 12/15/2010 - 15:20
Forums
Ice Core Drilling in West Antarctica 2010

Hello, Heidi! My name is Sarah Mix, and I've been following your expedition. I'm just curious; how many years of information can be found from the ice cores that you will soon be drilling? Thank you, and good luck with your work! Sarah Mix

Tue, 01/04/2011 - 19:55

Anonymous

Sarah, As you drill deeper and deeper into an ice sheet, each piece of ice you pull out of the borehole contains more time than the one right above it.
Why is this?
Think of all of the mass of the ice sitting on top of the bottom most layers of the Antarctic ice sheet! There is more than 10,000 feet of ice many places! What happens is that each year of accumulated snow, which at one time made up the flat white surface of Antarctica, is gradually squished by the next 10, 100, 1000, even 100,000 years of snow that falls after it.
At a place like WAIS Divide, snowfall will add up to 10 inches of new ice to the surface of the ice sheet each year. At the very bottom of the ice sheet, however, that 10 inches is squished so much it becomes much less than even 1 inch thick (think more like 1/16th of an inch at the very base of the ice sheet!).
We hope at WAIS Divide to find ice more than 100,000 years old near the bed of the ice sheet (our goal is 3300 meters deep, or just about 10,000 feet). It's difficult to predict exactly how old the bottom ice will be, because the ice isn't always squished evenly throughout the depth of the ice. What's more, does it snow EXACTLY 10 inches at your house every winter? Probably not---so we also have to wait and see how the variability, or difference, between each year of snowfall adds up to make the whole thickness of the ice sheet.
Did it snow as much 20,000 years ago at WAIS Divide as it does today? We couldn't answer this question without ice cores like the one Heidi is helping to drill!
Hope that long-winded response interests you!
Cheers.
Peter Neff
Glaciology graduate student, University of Washington
WAIS Divide Science Technician (2009-2010)

Wed, 01/05/2011 - 15:31

Heidi Roop

Sarah, we are hopeful that the WAIS Divide record will provide climate information over the last 100,000 years. Based on initial estimate of the ice core age, we started drilling ice this season, at a depth of 2,560 meters, that is ~20,000 years old. We are currently at a drill depth of 2,800 meters, or an ice age of ~30,000 years.-Heidi