Submitted by Anonymous on Mon, 12/13/2010 - 18:17
Forums
Ice Core Drilling in West Antarctica 2010

What is so special about the core site location - hasn't the Antarctic Ice Sheet been core before? Stay warm!

Best,

Al

Wed, 01/05/2011 - 14:44

Anonymous

There certainly are special characteristics of the WAIS Divide site that make it attractive to us scientists. Yes, we've made the Antarctic ice sheets into Swiss cheese with all of our ice core boreholes, but it turns out that, scientifically, the more ice cores the merrier! The WAIS Divide site is near the "divide" of the West Antarctic Ice Sheet. Think of this like the highest point in a river basin, where all the water (in the WAIS case, it's ice) is precipitated and flows from on its way to the ocean. Drilling near the ice divide is useful, as it often provides us with the flattest layers of ice preserved for the longest time. The ice tends to be thickest at the flow divide (think highest, again, like in a river basin), containing the most years of preserved ice and thus preserved climate information.
Also interesting about WAIS Divide is that the yearly snowfall adds almost 10 inches of new ice to the ice sheet every year. Most places in Antarctica see far less snow than that (did you know Antarctica is a desert?). This means that the deeper layers of ice, squished by overlying snow and ice mass, are thicker than at a place like the South Pole, where there is less than 1 inch of new ice added to the flat, white surface every year. We scientists like thicker annual ice layers because our measurement techniques require big chunks of ice to best explore levels of greenhouse gases--like carbon dioxide and methane. Sites with high snow accumulation, like WAIS Divide, will have on the order of 10's of years preserved in a sample 1 inch thick near the base of the ice sheet. A low snow accumulation site, like the South Pole, might have 100's of years preserved in that same 1 inch thick ice sample.
In paleoclimate ("old" climate) science, it's all about high-resolution.
Just like you want to have the highest-resolution television out there to properly enjoy your favorite movie, we want to have the clearest picture possible when we look at climate in the past. This is important, considering what we're seeing in the present climate around the world, right? If temperatures are rising now, we want to be really confident in our understanding of what temperatures have done in the past--from Antarctic ice cores, it turns out that temperatures and greenhouse gas levels are higher today than they've been in more than 800,000 years!
Another important point is that WAIS Divide is in West Antarctica, which is a smaller, lower-elevation ice sheet than East Antarctica. The West Antarctic appears more dynamic in its response to climate changes than East, so examining an ice core from the heart of WAIS may tell us more about how it responds to changes in temperature, local weather patterns, and more.
There are many more reasons, but I'll leave them out for the sake of not going on much longer. If anyone is further interested, it's possible to take up the "scientist" title yourself and grab some real ice core data! The National Snow and Ice Data Center keeps many of our ice core databases online. This is a good way to see just how many ice cores we have, and see what the science community has done with them.
http://www.ncdc.noaa.gov/paleo/icecore/current.html
Lots of good questions here on PolarTREC--I hope to take a bit of the load off of Heidi, as I know it's hard to keep up with these questions out there in the cold!
Peter Neff
Glaciology graduate student, University of Washington
WAIS Divide Science Technician (2009-2010)

Wed, 01/05/2011 - 15:32

Heidi Roop

Al! Thanks so much for your question. Just like with lake sediment coring, many different sites can yield different information, or tell a different story. WAIS Divide was chosen primarily because the high accumulation rate here at the ice divide. This high resolution will allow us to count annual layers (you know I love annual layers!) back approximately 40,000 years! We also expect decadal resolution back 100,000 years.
Although other ice cores, like the Vostok record, have made a significant contribution to climate science, the WAIS core will hopefully help us see in greater detail changes in climate that have been previously documented. Learning about leads and lags in the climate system, like those in temperature and greenhouse gas concentrations, requires greater resolution and the hope is that WAIS record will help us solve these parts of the climate puzzle.
How is the Svalbard research coming along? I am excited to hear more about the world of Arctic climate science! I miss the opposite pole :)

Wed, 01/12/2011 - 06:39

Anonymous

Thanks Heidi and Peter,Wow the opportunity to get decadal changes back 100,000 years is mind boggling! Svalbard is great and we are making good progress at understandingwhat controls yearly sedimentation in Lake Linne'! Currently in the middle of a major snow storm 12" plus! Be well. Al