Wednesday, July 22, 2015

Tarfala, 28th of June

This series of posts shares field notes from the study abroad course "Environment and Society in a Changing Arctic." The course begins at KTH Royal Institute of Technology in Stockholm, and then students from the University of Illinois and KTH travel north to conduct research in the Arctic. This blog was originally posted on KTH's Environment and Society in a Changing Arctic webpage.

by Corinna Röver

A warming climate causes glaciers to melt over time – but how do you actually measure the speed of glacier retreat? Today, we set out to learn more about a method used to answer this question. When a glacier recedes, it leaves behind glacial moraines – that is, soil and rock material transported and deposited by the glacier. These moraines, now exposed to sunlight, become hospitable to vegetation and lichens (consisting of a symbiosis of fungi and algae) start to grow on its rocks. Our field task was to measure the extent of these lichens, in order to calculate the time at which the glacier retreated and its moraines became exposed. Lichens grow approximately 0,2mm per year, and the bigger the lichen, the ‘older’ the moraine. We followed in the footsteps of researchers of the 1970s and used rulers to measure the diameters of lichens. Although this method is nowadays replaced by rock isotope measurements that offer more precise results, it is literally a good hands-on method to specify the age of the glacier-moraines. Our field task subjects were the Rhizocarpon geographicum lichens on two neighboring moraine ridges of the Storglaciären.

As we ploughed our way to the ridges through the slushy snow - our snowshoes had become a natural extension of our feet at this point - we were accompanied by two students from Stockholm University who came to Tarfala for their studies. They explained they use infrared measuring methods to investigate climate change, biodiversity and altitudes of micro climates in high alpine vegetation areas above 1200 meters above sea level. As this work has not been carried out before in this region, their research results will create a baseline that further research can build upon.

After the two had disappeared behind some slopes, we took our measurements, defined the aspects of the lichens (which direction they faced) and compared our results from the two ridges: while the lichen-diameters of Ridge number 1 extended from 5 up to 8 centimeters, the lichens on Ridge number 2 were considerably smaller, ranging from 1-3 centimeters in diameter. With some help from Pia and Hanna, we came up with the following conclusions: Ridge no. 1 is older and its rocks have been exposed since the 19th century or longer, while Ridge no. 2 might have become exposed in the 1910s – however, it still remains very difficult to date the moraine ridges through our method of lichen measuring.

We then treated ourselves to some knäckebörd-sandwiches and were free to explore the area on our own in the afternoon. Most of us hiked (in groups or individually) up to some nearby mountains surrounding the valley. Needless to say, the hiking in the stunning, sunny Tarfala valley area had become a favorite part of our stay at the research station.


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