The Franz Josef Glacier: A Case Study of a Glacier Showing Recent Retreat (2)
Learning Objectives: To assess the extent of Franz Josef’s retreat in the 20th Century To study related data To interpret this data using a living graph
Remember this...? Retreat of the Franz Josef Glacier since the 19th Century. Describe the pattern.
The following graph, also on your handout, shows the volume of ice in the Franz Josef Glacier in New Zealand’s Southern Alps mountain range. Similarly to the previous diagrams, it shows a glacial retreat due to ablation. Read the following statements and try to fit them on an appropriate part of the graph to tell the story of the Franz Josef’s retreat.
After a sharp decline in the glacier size, people start to worry about water supply. Between 1850 (end of ‘Little Ice Age’) and 1940, the world went through a long spell of warming. Glacial lakes, including a lake near Franz Josef, continue to grow. There are more westerly winds and more snowfall meaning the glacier advanced more than previously expected. After the ‘Little Ice Age’, glaciers around the world, including the Franz Josef, began to retreat. Between 1950 – 1980, there was a period of global cooling, and so afterwards, glaciers began to advance and grow. The westerly winds stop and less snowfall fall on the glacier. Although it didn’t get any colder, there was lots of snowfall in 2000-2004. Franz Josef is very reactive to small ‘mass-balance’ changes, which means if accumulation or ablation occurs, the glacier shows evidence of this fairly quickly. Carbon emissions are still increasing in the world, causing more global warming after 2004.