Submitted by Anonymous on Mon, 04/16/2012 - 03:32
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Airborne Survey of Polar Ice

This is Jen Heffernan's sixth grade science class and we love and appreciate all the journals and pictures we are able to share with you!! We are wondering what makes this glacier recede?

Mon, 04/16/2012 - 05:34

Anonymous

Hello!I am a chemistry teacher in Central Pennsylvania. I know very little about glaciers and the the research the Polar TREC team is conducting. I am interested in your mission and I am interested in learning more.
My questions may be rudimentary. Jen Heffernan's comment has me also wondering if there is an easy answer to what makes glaciers retreat. I am assuming that there are marked differences between the land-terminating glaciers and the sea-terminating glaciers. I assume that there are differences in thickness and ablation. Are there other differences? Is one expected to be more seasonal in the changes it undergoes? I read an article yesterday that claimed that the Himalayan glaciers in the Karakoram range have actually grown. Why does it seem as if discoveries like this seem to be contrary to what we have been told about global warming?
In one of your journal entries, you mentioned the instrumentation that will be used to map the surface. How are they used to capture various aspects of the topography to build the "big picture."
Tim, I read your 9 journal entries and enjoyed the pictures and your commentary. I have never followed a mission like this before. Towards the end of the school year, schools tend to be a little relaxed. I was hoping to read some of your entries to my students and show them your pictures.
Eason

Mon, 04/16/2012 - 16:42

Tim Spuck

It's great to hear from your 6th Grade Class in Oil City, Pennsylvania, and I'm glad you and your students are enjoying the expedition. Great question! Think about a glacier as a river of ice. Glaciers advance when ice builds up (for example during an ice age), and glaciers recede when more ice melts than is added to the system. As temperatures have increased around the globe the ice that makes up the glacier melts faster than it is replenished. As a result the glacier recedes. One reason scientists study glaciers is because they responding to changes in climate (e.g. increases in average global temperatures), and as a result they are help indicate the health of our planet.Hope you enjoy the video I am adding this morning.
Best wishes, Tim

Mon, 04/16/2012 - 17:12

Tim Spuck

Eason,Thanks for your questions! I'll try to address most of them, and some I will be covering in a bit more detail in future journal entries. My response to the question put forward by Ms. Heffernan's 6th grade class was the simple version. As with most things there are exceptions to the rules and that is why it is important to use lots of data and look at averages ... the big picture. It is true that some glaciers are advancing, but the number is very small compared to the ones that are retreating. There are other factors that can can cause a glacier to go through what appears to be a temporary acceleration. For example if something causes the glacier to flatten out it will appear as though it is advancing but that does not mean the there is more ice mass, it's just that the thickness of the glacier decreased. This is why the work IceBridge is so important. The on-board ice penetrating radar can measure changes in ice thickness over time, and other instruments can measure ice mass.
It is also true that sea terminating glaciers on average experience a more rapid retreat the land terminating glaciers. Water has a greater capacity to hold heat than land. For example if you place an ice cube on the table and you place another in a glass of water that is at the same temperature as the table, the ice cube in the glass of water will melt faster.
I'll try and address your other questions in some of my upcoming journal entries.
Best wishes, Tim