004 - Advance and Retreat

Geographic Knowledge and Understanding

The changing distribution of extreme environments over time, including the advance and retreat of glaciers and natural desertification.

Key Concepts

Scale is vital when studying the changing distribution of extreme environments over time. Climate change at a global scale is having an impact on the local scale such as natural desertification and glacial retreat (and advance). Natural processes are involved in both scenarios. There are possibilities that actions of humans can accelerate the processes.


  • To be able to describe and explain the changing distribution of extreme environments over time.

  • To be able to describe the global situation regarding the changes to glaciers over time.

  • To be able to explain the processes linked to the advance and retreat of glaciers.

  • To be able to explain the processes associated with natural desertification.

Key Terminology

            • Snout

            • Accumulation

            • Ablation

            • Equilibrium

            • Systems Diagram

Define the words above by using the useful links below:

Useful Links

Activity One - Describe

As I am sure you are well aware our climate is slowly warming up but this is not a new phenomenon. This relates to the first subunit of Climate Change in Paper Two. Our planets temperature has fluctuated throughout time and this has helped to cause the ice ages as well as the warm period we are currently experiencing. Watch the short clip below and describe the long term global trend in warming temperatures.

Earth's Long-term Warming Trend


Activity Two - Glacial Changes

Before we even begin to look at the different types of landforms a glacier can create we need to start with the basics and understand what glacier actually is, how it changes in mass and how it can move. Ultimately a glacier is just a slow moving body of ice very similar to a river just a much larger scale. Answer the questions below.

      1. How does a glacier actually form? Use the links in the 'Useful Resources' box to help you.

      2. Watch the youtube clip below and write notes on how glaciers move and how they help to shape the landscape.

      3. You defined what a system is for physical geography at the beginning of the lesson, now draw a systems diagram for a glacier.

      4. Using image two below describe the changes to the thickness of mountain glacial ice since the 1970s. Don't forget to include figures.

Useful Resources

Geology - Glaciers

Glacier Mass Balance

How do Glaciers Move?

Be Smart

Activity Three - Desert Changes

As you have seen in the previous activity glaciers can advance and retreat and the same is true for our arid regions. Desertification is the process of desert expansion often due to a lack of rain but humans can also be to blame. Desertification is an important process to study as it could have severe impacts to human habitation and on our levels of malnutrition. Answer the questions below:

      1. By watching the youtube clip above and reading the two articles in the 'Useful Resources' box, describe the natural and human causes of desertification.

      2. Using image three describe which areas of the world are vulnerable to desertification.

Useful Resources

Desertification - A Visual Disaster

Koln International School of Design

To Read

Our Planet's Extreme Environment by Codrington - Pages 38-39

Carbon Brief - Desertification

The Guardian - Desertification - A dangerous myth?

Exam Style Questions

State and explain one significant process involved in natural desertification. [1 + 3]

State and explain one significant process involved in glacial retreat. [1 + 3]