What’s going on at Bridge Glacier? – Time-Lapse Photography

This is my backhanded excuse for why I haven’t been updating this blog for awhile, namely that it’s been my “busy season”; getting stuff ready fieldwork, and tromping around glaciers in the name of science. This is my attempt to explain (the scientific basis of) why I’m doing it.

I’ve spent a lot of time over last couple months writing about how glaciers respond to changes in temperature, and how that response gets lost in the noise of other processes when the glacier is calving. In the case of Bridge Glacier, it’s an interesting study because it a very active glacier that is nearing the end of it’s calving phase. Bridge Glacier has retreated over 3.5 km in the last 30 years and has also thinned a tremendous amount. What’s even more astounding than the numbers is that NTS maps from the 1970s show our field camp to be partially underneath the ice front – it now takes over 2 hours of hiking to reach the terminus of the glacier.

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View of the calving front as Bridge Glacier spills into the lake.

Naturally, when faced with such staggering change over a relatively short period of time, we want to know and explain what is driving these changes. While it’s pretty clear that calving, the process of ice cracking off the glacier and creating large icebergs, is an important consideration in the changes we’re seeing at Bridge Glacier, it’s a little less clear how much of an effect it’s had (though I’ve made a guess).  Its also unclear if the changes in the rates of calving we’ve seen are being driven by an external forces, such as a changing climate or a warming lake, and if the external driver of calving actually changes over time.  It’s these questions that have formed the base of my summer work at Bridge Glacier.

In order to continuously monitor the front of the glacier, and determine when calving events happen, time-lapse cameras were set up at vantage points and are taking a picture every hour of the lower slopes of Bridge Glacier. With these photographs (which I will go download off the camera next week!) we’ll be able to date each calving event and make an estimate of its how much ice was released.

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This time-lapse camera shoots every hour of the day, and has been tasked with capturing the timing and size of calving events. It also has the added benefit of tracking iceberg movement. And it’s a beautiful spot.

One of the other great things about time-lapse photography is that we can actually use the sequential images to reconstruct how fast the glacier has been moving over the summer. By tracking a large rock, crevasse, or other easily recognizable object, you can monitor how far it moves over time. Understanding how fast the glacier moves will allow us to better estimate how much ice is being pushed into the lake.

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This camera is position perpendicular to the direction of ice flow. Photos from this camera will be used to calculate how fast the glacier is moving by tracking crevasses and rocks on the glacier, known as “feature tracking”. The small rope is to stop the solar panel from shaking in the strong katabatic winds coming down from the icefield.

All in all, having cameras shoot remotely all summer is a great tool. In a single photograph we get all kinds of great data, with the added bonus that everything is immediately visual. Plus, it makes for some great mountain eye-candy.

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Bridge Glacier, 5:00am, June 16, 2013.

…More to come…

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