Not Just a Pretty Face (Picture): Seminar Sum-Ups

As technology advances so to does our understanding of the planet. Penny How perfectly demonstrated this at a seminar I recently attended all about her PhD thesis. 

Aims

Using time-lapse photography Penny aimed to better understand the methods of dynamic alteration at the terminus of two tidewater glaciers (Fig 1).


Figure 1: Example of a Tidewater Glacier, Kronebreen in Svalbard, (Penny How's Blog)
Note: Tidewater Glacier - Glaciers that flow into the ocean.

Why

So, why is it important to understand glacier processes? Climate change or more specifically global warming leads to ice loss from glaciers and this impacts global sea level rise. However, there is still a limited understanding of how glacial change will affect sea level rise especially within different emission scenarios. There are two main ways in which ice transfers from glacier to ocean:


1) High temperatures promote glacier melting and surface melt channels funnel water into the oceans. Meltwater at the bottom of the glacier is also produced which enhances the slip and slide of the glacier. This produces more melt into the oceans as a positive feedback.

2) Calving events – when a chunk of ice breaks away from the glacier into the ocean. This leads to acceleration of the glacier movement.


These processes of ice loss are still somewhat a mystery therefore with the looming threat of sea level rise it is important to understand the processes happening now. 

Where

Penny’s project was based in Svalbard, located in the Arctic Ocean (Fig 2). Due to the decline of the coal industry Svalbard now relies heavily on tourism attracted to the glaciers. However, they are at risk as warmer waters are set to influx the Arctic consequently leading to high ice loss, retreat of the glaciers and a significant influence on sea level rise.


Two contrasting glaciers were chosen to be monitored, Kronebreen and Tunabreen (Fig 2).

Figure 2: Location of Svalbard, location of Kronebreen (red) and Tunabreen (green) within the archipelago, (Google maps, Glacierhub.org and Penny How's blog) 


Kronebreen

Kronebreen is the fastest retreating glacier in Svalbard, having retreated 2km in the last five years. Little information is known about changes at the terminus and how this contributes to overall ice loss of the glacier.

Tunabreen

 Tunabreen is dynamically different as it undergoes cycles of change. Experiencing times of normal motion then periods of relatively fast motion. Retreats rates are on average around 10 cm per day. Little is also known about stability and ice loss on a short-term basis. 
Overall they wanted to look at controls on retreat and understand the calving processes. 

Methods

As previously mentioned time-lapse photography was the main method for data collection at each glacier. Kronebreen (Fig 3) was monitored over a three-year period and Tunebreen just over two weeks.


The great thing about time-lapse photography is you can see how processes operate on a range of timescales chosen by you.

Figure 3: Example set up of the cameras at Kronebreen, Svalbard, (Penny How's blog)

Results

Kronebreen

From the images they could see that glacier lakes filling and draining led to a plume appearing at the glacier front. So, water must be leaving the glacier as a channel. They implemented melt modelling, hydraulic modelling and borehole measurements to estimate where the water channels could be. They found everything linked up and produced a hypothesised drainage system beneath the ice. 

 Previously the south side of the glacier had been retreating faster and this can be explained by the smaller drainage system in the south. Less efficient evacuation of the meltwater means it will pool and enhance basal lubrication and therefore speed up the rate of flow.


Tunabreen


They found that over the small time-period they could identify different types of calving processes. Most of the events occurred above the waterline, a notch is created from melting and this creates instabilities above leading to a large calving event. So, the ice loss is controlled by submarine melting. More melting leads to local instabilities at the terminus. Also, this stability is strongly liked to atmospheric and oceanic variability.


Wider Context


These findings will help researchers understand ice loss processes at the terminus of tidewater glaciers. This will help quantify the amount of global sea level rise attributed to dynamical changes of glaciers specifically at their terminus. Penny and her team have shown how useful time-lapse photography can be to view high detail change. This work may inspire more scientists to utilise seemingly normal technology and proves that it’s not always just a pretty picture. 


Meg


Links you may be interested in:

Penny's Blog - pages about her PhD and some amazing photos -
https://pennyhow.wordpress.com/research/phd/

Interesting blog all about glaciers, easy to read and again some great photos -
http://glacierhub.org/2016/05/13/photo-friday-kronebreen-glaciers-in-svalbard-2/

Penny's PhD Thesis -
How, P., 2018. Dynamical change at tidewater glaciers examined using time-lapse photogrammetry.
https://www.era.lib.ed.ac.uk/handle/1842/31103

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